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Total body water turnover and partitioning of salt excretion in glaucous-winged gulls, larus glaucescens Walter, Anne 1977

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TOTAL BODY WATER TURNOVER AND OF SALT EXCRETION  PARTITIONING  IN GLAUCOUS-WINGED  GULLS, LARUS GLAUCESCENS by ANNE WALTER B.A.  Grinnell  C o l l e g e , 1973  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in  t h e Department of ZOOLOGY  We a c c e p t t h i s t h e s i s as conforming to the r e q u i r e d standard  THE UNIVERSITY OF BRITISH COLUMBIA M a r c h , 19 77  0  Anne Walter, 1977  In p r e s e n t i n g an the  thesis  Library  shall  make i t f r e e l y  agree t h a t p e r m i s s i o n  scholarly  h i s representatives.  of  this  written  gain  University  ~z.Do\t>c^  of British  2075 Wesbrook Place Vancouver, Canada V6T 1W5  Columbia  Columbia,  I agree  that  f o r r e f e r e n c e and s t u d y .  for extensive  permission.  of  of B r i t i s h  copying o f this  thesis  by t h e Head o f my D e p a r t m e n t o r  I t i s understood  thesis f o r financial  Department  f u l f i l m e n t o f the requirements f o r  available  p u r p o s e s may be g r a n t e d  by  The  in partial  advanced degree at t h e U n i v e r s i t y  I further for  this  shall  that  copying or p u b l i c a t i o n  n o t be a l l o w e d w i t h o u t  my  ABSTRACT  1.  Two  aspects of  long-term s a l t  and  water  were measured i n G l a u c o u s - w i n g e d G u l l s , L a r u s T o t a l body w a t e r volume and birds  drinking  turnover  f r e s h w a t e r and  appearance r a t e .  Na ,  K,  +  CI  continuous  collection  gland  from b i r d s  fed  or a s a l t  load  2.  TBW  ion  f r e s h w a t e r and  Mean t o t a l  the 4.  fish  both  both'drinking  same as  and  regimes  over  THO  24  c l o a c a l and  fish  plus  a salt  salt  f o u n d t o be  dis-  hours salt load,  of regimes.  birds.  data  significant  fed b i r d s  79%  sea water d r i n k i n g  r a t e was  (0.064 m l / g - d a y ) ;  r a t e b a s e d on  T h e r e were no  this  the  value  from o t h e r  same is  birds.  d i f f e r e n c e s between  i n the  pattern  or  the  amounts  the of  excretion. 5.  S o d i u m and  c h l o r i d e were e x c r e t e d  e q u a l amounts f r o m t h e was  of  body w a t e r t u r n o v e r  predicted  fish  w a t e r by  only.  volume i s l a r g e compared t o o t h e r 3.  for  fish,  T o t a l body w a t e r volume was  body w e i g h t on  sea  excretions  were m e a s u r e d by excretions  glaucescens.  r a t e were m e a s u r e d i n  drinking  and  +  excretion  excreted  sodium, 6%  of  v i a the the  gland  cloaca.  total  excreted  were c o n t a i n e d  the  and  fish  salt  fish + salt  and  approximately Most  T h i r t y - e i g h t percent  p o t a s s i u m and i n the  cloaca.  in  salt  groups o f  58%  gland gulls.  of the  potassium of  total  secretion of  the  total  chloride both  iii 6.  The  fluid  and  e x c r e t i o n were a n a l y z e d between t h e  two  birds,  51.8  +  K  was  cloacal  +  excreta.  rates  of  cloacal  The  stancy  as  The  was  the  birds  a buffer  o f TBW  fish  solid  detected given  turnover  +  and  i n the only  fed  volume may  divided  fish  + salt  of  + 4.5%  the  fluid  fed of  the  cloacal  portion  l o a d had  smaller  amounts  only. lower of  birds. be  advantageous t o ingestion.  suggests that  adapted to t h e i r  cloacal  were  61.8  a salt  excess s a l t  rate  and  portion  w a t e r l o s s and  against  the  Cations  c l o a c a l Na  i n the  l a r g e TBW  9.  The  the  The  gulls  marine con-  are  e n v i r o n m e n t where s a l t ,  r e s u l t s suggest that  and  e s p e c i a l l y the  ion excretion  cesses  f o r f e d and 10.  the  two  the  of  but  water, i s a s t r e s s .  fluids for  found  In  s o l i d s compared t o t h e  specifically not  of  evaporative  8. birds  7.8%  portions  for ions.  portions.  Chloride  7.  solid  primary  entire other  more s u b t l e  and  u n f e d b i r d s may  These d a t a imply  process of  salt  that  that  gland,  important  routes  osmoregulatory  although the to  salt  salt  pro-  gland  stress,  water metabolism a l s o  mechanisms.  cloacal  be d i f f e r e n t .  of marine b i r d s and  salt  c l o a c a l s o l i d s are  f o r fed birds  adaptation  the  is  the  involves  iv  TABLE OF  CONTENTS Page  TITLE  PAGE  .  .  ABSTRACT  i i i  TABLE OF CONTENTS  iv  L I S T OF TABLES  vi  L I S T OF FIGURES L I S T OF APPENDICES ACKNOWLEDGEMENTS  v i i viii ix  I.  INTRODUCTION  1  II.  MATERIALS AND METHODS  6  A. M a i n t e n a n c e o f e x p e r i m e n t a l a n i m a l s . . . . B. T o t a l body w a t e r t u r n o v e r — e x p e r i m e n t a l procedures 1. E x p e r i m e n t a l r e g i m e 2. A n a l y t i c a l p r o c e d u r e s . . . . . . . . . a. Sample p r e p a r a t i o n & c o u n t i n g . . . . b. C a l c u l a t i o n s c. A l l o m e t r i c a n a l y s i s C. I o n s and w a t e r i n s a l t g l a n d s e c r e t i o n and c l o a c a l e x c r e t a — e x p e r i m e n t a l procedures 1. E x p e r i m e n t a l r e g i m e 2. Sample p r e p a r a t i o n a. S a l t g l a n d s e c r e t i o n b. C l o a c a l e x c r e t i o n c. I o n a n a l y s i s d. E s t i m a t i o n o f s e c r e t i o n volume . . . e. E s t i m a t i o n o f e v a p o r a t i v e w a t e r l o s s (EWL) f . D i s c r i m i n a t i o n between s e c r e t o r s and n o n s e c r e t o r s 3. S t a t i s t i c a l analyses  6 6 6 7 7 8 9 9 9 12 12 12 14 15 15 16 16  V  Page III.  RESULTS A.  B. C. D. E. IV.  17  T o t a l body w a t e r t u r n o v e r . 1. B i r d w e i g h t s 2. TBW volume 3. TBW t u r n o v e r 4. A l l o m e t r i c c o m p a r i s o n s a. TBW volume b . TBW t u r n o v e r S a l t g l a n d and c l o a c a 1. I o n and f l u i d o u t p u t 2. D i s t r i b u t i o n o f i o n e x c r e t i o n I o n P a r t i t i o n i n g Between C l o a c a l F l u i d and S o l i d P o r t i o n s Evaporative water l o s s Comparison between s a l t g l a n d s e c r e t o r s and n o n s e c r e t o r s  17 17 17 17 20 20 20 24 24 24 24 30 30  DISCUSSION A. B. C.  V.  .  34  T o t a l body w a t e r volume and turnover rate I o n s and w a t e r i n s a l t g l a n d s e c r e t i o n and c l o a c a l e x c r e t i o n Conclusions  SUMMARY  .  34 . . . .  37 46 49  REFERENCES  52  APPENDICES  56  vi  L I S T OF  TABLES  Table I  II III  IV  V  VI  VII  VIII  Page Total rates Larus  body w a t e r volume and t u r n o v e r f o r Glaucous-winged G u l l s , g l a u c e s c e n s (+ SEM)  18  C o m p a r i s o n o f t o t a l body w a t e r volume among a v i a n s p e c i e s  22  Ion c o n t e n t o f s a l t g l a n d s e c r e t i o n and c l o a c a l e x c r e t i o n c o l l e c t e d o v e r 24 h o u r s f r o m G l a u c o u s - w i n g e d G u l l s , Larus glaucescens given e i t h e r f i s h , f i s h + s a l t , or s a l t only. The v a l u e s a r e p r e s e n t e d as means + SEM  25  W e i g h t and i o n c o n c e n t r a t i o n o f f l u i d and s o l i d p o r t i o n s o f c l o a c a l e x c r e t a c o l l e c t e d o v e r 24 h o u r s f r o m G l a u c o u s winged G u l l s , Larus glaucescens given e i t h e r f i s h , f i s h + s a l t , or s a l t only. The v a l u e s a r e p r e s e n t e d as means + SEM  29  E v a p o r a t i v e w a t e r l o s s d u r i n g 24 h o u r s from Glaucous-winged G u l l s , Larus glaucescens fed f i s h , f i s h + s a l t , or s a l t only. D a t a v a l u e s a r e means + SEM 7  31  I o n c o n t e n t o f s a l t g l a n d and c l o a c a l i o n e x c r e t i o n : amount o f i o n (yeq) e x c r e t e d p e r 24 h o u r s by s e c r e t i n g and n o n s e c r e t i n g Glaucous-winged G u l l s , Larus glaucescens. The v a l u e s a r e means + SEM  32  W e i g h t and i o n c o n c e n t r a t i o n s o f f l u i d and s o l i d p o r t i o n s o f c l o a c a l e x c r e t a c o l l e c t e d o v e r 24 h o u r s f r o m s e c r e t i n g and n o n s e c r e t i n g G l a u c o u s - w i n g e d G u l l s , Larus glaucescens  33  C o m p a r i s o n o f 24 h o u r w a t e r and i o n output i n G u l l s , Larus glaucescens, and Ducks, Anas p l a t y r h y n c h o s . . .  44  vii  L I S T OF  FIGURES  Figure 1  2  3  4 5  6  7  Page A p p a r a t u s f o r 24 h o u r s a l t g l a n d cloacal excretion collections  and 11  F l o w d i a g r a m i n d i c a t i n g methods o f s e p a r a t i o n and a n a l y s i s o f c l o a c a l samples L o s s o f t r i t i a t e d w a t e r (THO) f r o m t h e e x t r a c e l l u l a r f l u i d o f one G l a u c o u s w i n g e d G u l l (#4) o v e r a two week p e r i o d Relationship (TBW) volume  13  . .  between t o t a l body w a t e r and body w e i g h t (W)  19 21  R e l a t i o n s h i p between t o t a l body w a t e r (TBW) t u r n o v e r r a t e and body w e i g h t (W) f o r a v a r i e t y o f a v i a n s p e c i e s . . . .  23  The p a r t i t i o n i n g o f i o n s and w a t e r i n 24 h o u r s a l t and c l o a c a l c o l l e c t i o n s from Glaucous-winged G u l l s , Larus g l a u c e s c e n s p r e s e n t e d as p e r c e n t a g e s o f t o t a l i o n and w a t e r e x c r e t i o n  26  R e l a t i o n s h i p between c a t i o n c o n c e n t r a t i o n s i n t h e f l u i d p o r t i o n and s o l i d p o r t i o n of the c l o a c a l e x c r e t i o n  28  viii  L I S T OF  APPENDICES  Appendix  Page  I  Computer p r o g r a m  56  II  Data from i n d i v i d u a l b i r d s f o r i o n and f l u i d e x c r e t i o n d u r i n g a 24 hour c o l l e c t i o n p e r i o d  58  E f f e c t s o f TBW volume on t h e estimated osmotic e f f e c t s of a hypertonic s a l t load  62  III  ix  ACKNOWLEDGEMENTS  Many p e o p l e Those who puter Dr.  loaned  e q u i p m e n t , gave a d v i c e  programming i n c l u d e Dr.  P i e r r e K l e i b e r , Dr.  Joan Meredith, Coubaraki  and  generously my  have c o n t r i b u t e d t o t h i s  absence.  own  field  J o h n E. P h i l l i p s ,  Dolores  Sandra A l l i s o n .  r a n and  observations.  Numerous p e o p l e  d i v e r s e ways d u r i n g  this  Sue  particularly  they  helped  friends Chris  t o be  with  French,  my  Nick  Roe,  and  ported  and  e n c o u r a g e d my  visor,  Dr.  Maryanne R.  support  me. by  and  i t s typist,  efforts  Financial  Peggy  support  supported  gulls.  the  project.  thanked  M.  R.  me  her  in and times  Many Mansfield,  My  super-  f o r her  moral  l a b o r a t o r y space, advice laboratory experience  care  given  to t h i s  and with  manuscript  Ellis. for this  r e s e a r c h was  t h e N a t i o n a l R e s e a r c h C o u n c i l o f Canada g r a n t awarded t o Dr.  very  Mary P e r k i n s  S w i f t , Don  in this  s h a r i n g much o f h e r  Mrs.  also  Nancy K l e i b e r c o n s i s t e n t l y s u p -  Hughes i s t o be  I greatly appreciate  Stella  remembered f o r t h e many  Michael  as w e l l as p r o v i s i o n o f  criticism,  Bradley,  for providing  c a r i n g f o r the  parents,  McEwen,  c o m p u t e r programs i n  research period.  f e e d i n g and  especially  thanked  com-  Ian  Timothy  Lauriente  appropriately altered  with  Dr.  Lauriente,  Dolores  S a r a h Grove i s t o be  Krepp are  or helped  J o h n G u t k n e c h t , Dr.  William Holt,  research project.  Hughes •. i n t h e  provided  by  A-3442  Department of  Zoology.  1  I.  INTRODUCTION  The o s m o r e g u l a t o r y p r o b l e m s are of  d e t e r m i n e d by t h e i r the oceanic  high  e n v i r o n m e n t w h i c h combines  and t e r r e s t i a l  dant b u t o f t e n s a l t y ;  environments.  the g u l l ' s  diet  fluids;  terrestial  life  w a t e r l o s s e s due t o r e s p i r a t o r y excess  salts,  evaporation  kidney  excretion of hypertonic  can, but r a r e l y  hypertonic & King,  levels  1972).  Even  wastes.  salt  solutions.  i t i s the s a l t  and s m a l l This  The a v i a n  19 70;  Farner  gland,  loca-  t h a t e l i m i n a t e s e x c e s s s a l t as  s e c r e t i o n (Schmidt-Neilsen,  though t h e s a l t  I n sum,  and w a t e r b a l a n c e .  o f s o d i u m o r c h l o r i d e (Hughes,  In marine b i r d s ,  salt  and e x c r e t i o n o f  does, produce a u r i n e c o n t a i n i n g  i n t h e head o f t h e b i r d ,  a hypertonic  respect to the  l a r g e amounts o f s a l t  amounts o f w a t e r t o r e m a i n i n s a l t requires  W a t e r i s abun-  imposes o b l i g a t o r y  n i t r o g e n and o t h e r m e t a b o l i c  these b i r d s need t o e x c r e t e  aspects  o f f i s h and c r u s t a c e a n s i s  i n p r o t e i n and c a n be h y p e r t o n i c w i t h  b i r d ' s body  ted  f a c e d by m a r i n e b i r d s  gland provides  e t a l . , 1958).  an a d e q u a t e means f o r  h y p e r t o n i c NaCl e x c r e t i o n , i t i s p o s s i b l e t h a t marine b i r d s also are  use o t h e r mechanisms t o cope w i t h  salt  loading.  There  two p h y s i o l o g i c a l p a r a m e t e r s w h i c h i n f l u e n c e o s m o r e g u l a -  tion—1) routes  r a t e and r o u t e s  of salt  turnover.  o f water turnover,  and, 2) r a t e and  2  T o t a l body w a t e r of  the  of  drinking  (TBW)  f l u x of water through rate,  =  an  evaporation  excretion—variable e inputs  turnover rate  the  that  are  interdependent  Changes i n TBW  be  t a k e n as  I f marine b i r d s drink by  salt  indices of are  mew  & Cade, A  i n TBW  sea  water  that  species  equations.  to  those  f r o m d a t a on  stressed  species  other  avian  i n a group o f  by  by  or,  (Bartholo-  rate  species TBW  by  effect  of  drinking  the  regime.  The  The  values  f o r TBW  for  indicate  turnover rate  Larus  regime two  was  and  sets  modify  type of d r i n k i n g water  avail-  1  TBW  gulls  of  do  s e a w a t e r on  t h e n compared t o n o n - m a r i n e b i r d s  marine  equations  Glaucous-winged G u l l s ,  a seawater d r i n k i n g  water  allometric  the  often  a freshwater drinking  i n response to  the  means o f  measurements were compared t o d e t e r m i n e i f t h e  ingestion.  rate  turnover rate  from v a l u e s p r e d i c t e d  f i r s t , during  second, d u r i n g  The  commonly  i s expected  volume and  environmental adaptations.  glaucescens,  able.  and  ingestion.  changes i n d r i n k i n g  adapted to or  for other  Variations  measured t w i c e  drinking  (i.e.,  regimes  i n d i c a t i n g whether o v e r a l l  e n v i r o n m e n t i s t o compare TBW  specific  to  turnover rate  s e c o n d means o f  generated  water  1963).  metabolism i s uniquely  this  water d r i n k i n g  adaptation  w a t e r , no  of  turnover rate  s i m i l a r to passerines,  or b r a c k i s h  extrapolation,  sea  rate  function  and  volume b e t w e e n f r e s h w a t e r and may  It is a  rate,  parameters  e outputs).  organism.  is indicative  turnover  responses to  turnover  was  seawater  r a t e were a l s o  compared  3  to those o f other determine  avian  species  i f the turnover  by a l l o m e t r i c a n a l y s i s t o  r a t e s measured a r e unique t o t h e  gulls. Salt in  gland  secretion i s often considered  response t o a s a l t  indications salt  that the s a l t  secretion.  reported  load.  However, t h e r e  gland  Firstly,  t o occur  are at least  spontaneous s a l t  s e c r e t i o n s have been  comm.), and s e c o n d l y ,  amounts o f i o n e x c r e t e d  i n spontaneously voided  are  f o r the excretion of dietary  (Hughes, 1970, 1 9 7 2 a ) . two  routes  feeding  However, t h e r e l a t i v e  have n o t b e e n m e a s u r e d  regimes.  Therefore,  two  must p a r t i c i p a t e i n n o r m a l  (Hughes, 1970; G r o v e , p e r s .  t o o low t o a c c o u n t  only  c l o a c a l samples salts  r o l e s of these  f o r marine b i r d s under  i n the present  the  study,  normal  relative  r a t e s o f e x t r a r e n a l a n d r e n a l m o n o v a l e n t i o n e x c r e t i o n were m e a s u r e d by c o l l e c t i n g excreta  salt  f o r a 24 h o u r p e r i o d Three i n v e s t i g a t o r s  gland  s e c r e t i o n s and c l o a c a l  from f e d g u l l s . ( J o h n s o n , 1969; Hughes,  McNabb e t a_l. , 1973) have m e a s u r e d s i g n i f i c a n t i o n s bound t o c l o a c a l s o l i d s domestic sidered  fowl  fractions of  i n hawks, young k i t t i w a k e s and  r e s p e c t i v e l y , b u t t h e s e i o n s have n o t b e e n  i n most s a l t  precipitated  1972b;  and water b a l a n c e s t u d i e s .  i o n s do n o t c o n t r i b u t e  of the c l o a c a l f l u i d ,  they represent  can  be e x c r e t e d  the  c l o a c a l m a t e r i a l was d i v i d e d  the  percentage o f c l o a c a l l y  Since  t o the osmotic  ions  that  In t h i s  i n t o two p o r t i o n s  excreted  these  pressure  a portion of ions  w i t h o u t any a c c o m p a n y i n g w a t e r .  con-  study,  to assess  i n s o l u t i o n compared  4 to ions extent gland  p r e c i p i t a t e d with  t o which monovalent ions  serve  a r e i n d i c e s o f how w e l l  water while  excreting  I t was d e c i d e d order  feeding the  to simulate increases  p o r t i o n o f the c l o a c a l  the b i r d  i s adapted t o con-  salts.  t o do t h e s e e x p e r i m e n t s w i t h  pattern are  alters  of salt  e x c r e t i o n has n o t been q u a n t i f i e d .  associated with  both marine s p e c i e s  tein  metabolism r e s u l t s i n n i t r o g e n  uric  19 7 3 ) . valent  protein diets  a c i d and ammonia The u r i c ions  osmolarity  and some  excretion,  Salt  (Holmes e t a l . , 1968; McNabb e t a l . ,  response  lost  was s i m i l a r i n b o t h c a s e s , t h e f e d b i r d s was n e a r l y  Gulls  t o an e q u i v a l e n t  body w e i g h t o f s e a w a t e r ) g i v e n percentage o f each l o a d  mono-  to the  (as much as 50% o f t h e c a t i o n s )  f e d and u n f e d H e r r i n g  terms o f t h e i r  Pro-  predominately  a c i d i s p r e c i p i t a t e d and combines w i t h  of the urine  glands  1966).  i n t h e u r i n e b u t t h e ammonia c o n t r i b u t e s  compared  i n the  falconiforms  (Cade & G r e e n w a l d ,  (Holmes e t a l . , 1968; J o h n s o n , 1969; D o u g l a s , (19 70)  to affect  However, t h e r o l e o f f e e d i n g  ingest high  by  Since  p r o t e i n a s s i m i l a t i o n and p r o b a b l y  that  in  fed birds  a natural physiological state.  excretion patterns.  The  by t h e s a l t  r a t e o f i o n uptake from the g u t , i t i s expected  salt  as  c l o a c a l contents.  are excreted  and p r e c i p i t a t e d i n t h e s o l i d  excreta  in  the s o l i d  1970).  (Larus salt  by stomach t u b e .  v i a each route  that  lost  Douglas d i d n o t determine t h e i o n content  argentatus)  l o a d (10% Although the  i n 3.5-4.0 h o u r s  t h e amount o f f l u i d twice  Douglas  lost  cloacally  by t h e u n f e d b i r d s .  o f the s o l i d  cloacal  5  material.  Since  administered  and t h e bound  Douglas's study feeding  an u n p h y s i o l o g i c a l l y  c l o a c a l ions  does n o t r e a l l y  under n a t u r a l  conditions.  s t u d y , two b i r d s were g i v e n t o t h e same 24-hour  only  collection  the e f f e c t o f f e e d i n g  N  address  salt  load  itself  to the r o l e o f  and w a t e r  Thus, i n the  a salt  was  not determined,  on t h e n o r m a l p a r t i t i o n i n g o f s a l t  by a b i r d  assess  large  l o a d and  as t h e f e d b i r d s  on t h e p a t t e r n  excretion  present subjected  i n order  of s a l t  to  excretion.  6  II. A.  MATERIALS AND  Maintenance o f Experimental The  during  METHODS  Animals  Glaucous-winged G u l l s  this  study  in  the vivarium  to  five  were o b t a i n e d  (Larus  b i r d s were h e l d i n e a c h o f 4 w i r e  flying  tification  on t h e i r  bands were p l a c e d  given  (Clupea  palasii)  a multiple vitamin  Columbia.  mesh c a g e s  legs.  (approximately  60 g) d a i l y and  supplement about every  5 days.  each cage.  The w a t e r was c h a n g e d a n d t h e c a g e s washed  Experimental  mental procedure.  2.5  using  a 1.0 ml  o r 3.0 m c i THO  Nuclear)  dishpans i n daily.  Procedures  the following experi-  E a c h b i r d was w e i g h e d and p l a c e d  r e s t r a i n i n g board.  Water  regime.  S e v e n b i r d s were s t u d i e d u s i n g  vein  i n 2 plastic  T o t a l Body W a t e r T u r n o v e r — E x p e r i m e n t a l  iden-  E a c h b i r d was f e d  and d r i n k i n g was p r o v i d e d  1.  feathers  and c o l o r e d p l a s t i c  for bathing  B.  Three  (2m l o n g  The b i r d s ' w i n g s and t a i l  were k e p t c l i p p e d t o p r e v e n t  herring  used  as f l e d g l i n g s i n 1973 a n d h e l d  of the U n i v e r s i t y o f B r i t i s h  X 1.2m w i d e X 0.76m h i g h ) .  bait  glaucescens)  A 1.0 ml b l o o d heparinized (spec.  sample was t a k e n  from 1 l e g  tuberculin syringe.  a c t . = 100 m c i / g , New  i n 0.5 ml o f i s o t o n i c  on a  Then,  England  s a l i n e was s l o w l y i n j e c t e d  into  the c o n t r a l a t e r a l l e gvein taking care  flow  of labeled blood.  t o prevent  The b i r d was r e t u r n e d  back-  t o i t s cage.  7  After  4 hours  taken.  The  ( t i m e d e s i g n a t e d t ) a 1.0  b i r d was  returned  t o i t s cage,  a f t e r m a i n t a i n e d on i t s n o r m a l Blood for  samples  ml b l o o d sample f e d , and,  f e e d i n g and w a t e r  TBW  adapted over a p e r i o d  water.  tained  After  1 week on above was  on s e a w a t e r .  the  experiment.  the  experiment 2.  One  bird  (#5)  after  to a l a b e l l e d  aliquot  sea water,  the promain-  m e a s u r e d a t t h e end  died early  6 birds  in this  phase  of  of  i n the study.  and c o u n t i n g  a b l o o d sample 1.0  i n an I n t e r n a t i o n a l  ml  strength  r e p e a t e d w h i l e t h e b i r d s were  Sample p r e p a r a t i o n  transferred  strength  were  procedures  Immediately  6000 rpm  full  samples  these b i r d s  o f 1 month t o f u l l  Body w e i g h t was  leaving  Analytical a.  0.1  of blood  measurement on a f r e s h w a t e r r e g i m e ,  cedure d e s c r i b e d  An  regime.  t h e n e x t 2 weeks.  gradually sea  there-  were t a k e n f r o m a l t e r n a t e l e g s e v e r y o t h e r day  F o l l o w i n g completion of the s e r i e s for  was  ml  centrifuge  Model  o f each plasma  was  HN  t a k e n , i t was t u b e and  Centrifuge  sample  was  added  spun  at  f o r 6 minutes. t o 10 ml  of  @ Aquasol  scintillation  potassium glass shaken cpm was plasma and  cocktail  counting vials  v i g o r o u s l y by h a n d . e x c l u d e d by c o n t r o l t h a t was  stored  Any  (New  E n g l a n d N u c l e a r ) i n low  (Wheaton S c i e n t i f i c ) effect  samples  n e u t r a l i z e d by NaOH.  o f plasma  u s i n g TCA The  i n opaque c o v e r e d c o n t a i n e r s  proteins  on  precipitated  samples  i n the  and  were  sealed  refrigerator  8  for  at least  2 4 hours p r i o r  disintegration  to counting to allow  of a l l s c i n t i l l a t i o n s  with b i o l o g i c a l  compounds.  to counting.  to l i g h t  to l i g h t  counter  ( N u c l e a r C h i c a g o ) w i t h programmed window  used t o count a l l samples.  minutes  ( t o a maximum o f 10  p e r minute  interactions  taken not to  samples  was  prior  C a r e was  due  time f o r  An  expose  ISOCAP 300  liquid  beta  selections  Samples were c o u n t e d f o r 10  c o u n t s ) and r e c o r d e d as c o u n t s  (cpm).  Quench c u r v e s were g e n e r a t e d by r e p e a t e d c o u n t i n g o f  @ THO  spiked Aquasol  to which  o f a v i a n p l a s m a were added. tion,  t h e sample  c o u n t i n g was  was  stored  increasing  amounts  Subsequent  t o each plasma  i n darkness  repeated 5 times.  disintegrations  p e r minute  Raw  (dpm)  (0.0-1.0  f o r 24 h o u r s  ml)  addi-  and  c o u n t s were c o n v e r t e d t o  by  reference  to these  quench  curves.  aid  b.  Calculations  The  calculations  o f a PDP  11/45  gram i s l i s t e d the d i l u t i o n  and  computer  i n Appendix  (Digital I.  o f i n j e c t e d THO J  A sign  test  d a t a p l o t t i n g were done w i t h t h e  TBW  drinking  for paired  regimes  error  o f t h e mean  (SEM)  volume was  #9100b).  pro-  calculated  (Larkin,  samples  was  from  u s e d t o compare t h e  d u r i n g t h e f r e s h w a t e r and 19 7 4 ) .  were d e t e r m i n e d  sea-  Means and s t a n d a r d f o r TBW  t u r n o v e r r a t e on a Programmable H e w l e t t P a c k a r d (Model  The  at t . o  v a l u e s o b t a i n e d from the b i r d s water  Corporation).  volume  and  Calculator  9 c.  Allometric  Values mined by  f o r TBW  e i t h e r THO  tained  from the  Linear  regression  and  TBW  to obtain  volume and  l o s s or  literature  turnover  done w i t h t h e  analysis  a i d of  equations  from the  of  the  a PDP  the  15  i n the  bird  volume o r  i n grams, and  logarithims  log  b are  the  rate, W  i n t e r c e p t and  If  Experimental day  to insure  that  b i r d was  slope  of  The  an  experiment the  b i r d was  fed a  the  appropriate  given meq  b i r d was  an  extra  N a C l was left  alone  for sufficient  prevent r e g u r g i t a t i o n , the  bird  ate  salt  load,  placed f o r the  pre-  a t i t s normal  hand-fed or observed u n t i l  7.35  minimum t i m e r e q u i r e d  Cloacal  regime  t o be  containing  feeding.  and  ( S a r t o r i u s : Kilomat balance) I t was  capsule to  of  time.  the  the  line.  weighed h e r r i n g  eaten  computer  i s weight of  I o n s and Water i n S a l t G l a n d Secretion E x c r e t a — E x p e r i m e n t a l Procedures  feeding  volume  W  C.  the  o f TBW  form:  regression  On  ob-  species.  Corporation)  the  1.  deter-  d r i n k i n g r a t e were  (Digital  turnover  a and  rate  l o g a r i t h i m o f body w e i g h t were  log Y = a + b where Y i s TBW  turnover  f o r a number o f a v i a n  analyses r a t e on  TBW  the  the  fish  entire  was fish.  a gelatin  i n the  fish  prior  next 4 hours,  d i g e s t i o n of  b i r d ' s normal f r i g h t  the  fish  response.  the to  10  The  b i r d was w e i g h e d , p l a c e d  sling  i n a soft  restraining  and h e l d i n an u p r i g h t p o s i t i o n w i t h i n t h e c o n f i n e s  o f a wooden  frame  (Figure 1).  l o a d were w e i g h e d a n d p l a c e d to s a l t of  cloth  loading.  The b i r d s g i v e n o n l y  i n the r e s t r a i n i n g  Three g e l a t i n  3200 y e q N a , 5 0 0 0 +  yeq K  +  capsules  the s a l t  sling  prior  containing a  total  and 8200 y e q C l ~ were p l a c e d i n  the b i r d ' s g u l l e t  f o l l o w e d by 50 ml o f d i s t i l l e d  water  by  The b i r d  but c o l l e c t i o n  stomach t u b e .  salt  gland  s e c r e t i o n and c l o a c a l  Cloacal tainer  remained  that  fluid  fitted  over  the  s i d e and a p i e c e o f p l a s t i c  mouth b e n e a t h t h e s c r e w c a p .  b o t t l e with  Salt  that  the b i r d  c a r r i e d both  bottle.  bottle  (with the base t h e head o f t h e  f r o m wooden  containers with  t h r o u g h o u t t h e 24 h o u r p e r i o d . were washed w i t h  long disposable  frame and were  were r e c o r d e d  at intervals  A t t h e end o f t h i s distilled  time,  the  w a t e r by means o f a  p i p e t t e i n s e r t e d t h r o u g h t h e mouth o f t h e  r e w e i g h e d and r e t u r n e d  so  i t i f i t moved.  The 2 c o n t a i n e r s were removed and t h e b i r d  immediately  cut i n  and t o t h e s l i n g worn by t h e b i r d  T e m p e r a t u r e and h u m i d i t y  nares  a hole  container  s e c r e t i o n was  ends) o v e r  B o t h b o t t l e s were s u s p e n d e d  bird's  gland  by p l a c i n g a s e c o n d p l a s t i c  t o each other  The  con-  screening placed over the  removed and a i r - h o l e s c u t i n b o t h  attached  i n a preweighed  t h e rump o f t h e g u l l .  an i n v e r t e d 1 g a l l o n p l a s t i c  bird.  was n o t begun f o r 4 h o u r s  samples were c o l l e c t e d  was  collected  i n the s l i n g  given  t o i t s cage.  was  11  F i g u r e 1. A p p a r a t u s f o r 2 4-hour s a l t g l a n d and c l o a c a l excretion collections. Gull i s placed i n a cloth s l i n g (shaded) w h i c h i s s u s p e n d e d f r o m t h e wooden frame by f l e x i b l e c o r d ( d o t t e d l i n e s ) . The c o n t a i n e r s (1 g a l l o n p l a s t i c j u g s w i t h e i t h e r t h e b o t t o m o r s i d e removed) a r e s u p p o r t e d by t h e frame and a t t a c h e d t o t h e s l i n g by c o r d ( d o t t e d l i n e s ) . A b i t of p l a s t i c s c r e e n i n g was p l a c e d o v e r t h e mouth o f t h e c o n t a i n e r f o r c l o a c a l s a m p l e s and h e l d i n p l a c e by a r u b b e r b a n d a t t h e n e c k and t h e l i d o f t h e c o n t a i n e r . The c i r c l e s on t h e c o n t a i n e r o v e r t h e b i r d ' s h e a d r e p r e s e n t a i r - h o l e s . A f a n was p l a c e d t o draw a i r f o r w a r d through t h i s container. The b i r d ' s w e i g h t i s s u p p o r t e d b u t i t may w a l k t o and f r o w i t h i n t h e f r a m e .  11a  12  2.  Sample a. At  Salt  total  secretion  25 o r 30 ml o f 15 meq/1  i n a sealed container  LiCl.  chloride i n 3 trials  with  b.  Cloacal excretion  The  plastic  increase  material  i n w e i g h t was  excreted  spiked  b o t t l e used  at a later  removal  The f l u i d  f r o m Hughes  weighed v i a l . fluid  cloacal  (1972b).  sample were i n i t i a l l y  excre-  amount o f  ( F i g u r e 2) was and s o l i d  separated  f o r 1 hour through the screen  The modified  portions  by a l l o w i n g t h e into a pre-  The v i a l was r e w e i g h e d t o d e t e r m i n e t h e w e i g h t  excreta. The  remaining  the  container  the  container.  a collection T h i s was  recovery  by t h e c l o a c a i n t h e 24 h o u r p e r i o d .  slightly  sample t o f i l t e r  date f o r  f r o m t h e b i r d and  t a k e n as t h e t o t a l  diagram  of the c l o a c a l  The  was  containers.  for collecting  after  sample  was  95% f o r s o d i u m and 101%  procedure o u t l i n e d i n the flow  of  This  and a n a l y s e d  on t h e c o n t a i n e r w a l l s was  t i o n was w e i g h e d i m m e d i a t e l y the  period the container  s o d i u m , p o t a s s i u m and c h l o r i d e c o n t e n t .  of s a l t for  gland  the end o f t h e c o l l e c t i o n  rinsed with frozen  preparation  m a t e r i a l was  scraped  and 50 ml o f d i s t i l l e d This  f l u i d was  from the s i d e s o f  w a t e r was  drained  through  used t o r i n s e the screen  into  b o t t l e t o f o r m t h e 'wash' p o r t i o n o f t h e s a m p l e .  r e f r i g e r a t e d overnight  pended s o l i d s .  The  'wash' was  p r e - w e i g h e d Whatman #1 f i l t e r  to allow  settling  subsequently  o f the sus-  filtered  through  p a p e r and t h e m a t e r i a l on t h e  13  j  F i g u r e 2. F l o w d i a g r a m i n d i c a t i n g methods o f s e p a r a t i o n and a n a l y s i s o f c l o a c a l s a m p l e s . Processes are l i s t ed on t h e l e f t - h a n d s i d e and p o r t i o n s t h a t were s u b sequently analyzed f o r i o n contents are underscored on t h e r i g h t - h a n d s i d e o f t h e d i a g r a m .  13a  CLOACAL SAMPLE weigh & f i l t e r through screen Fluid  portion  scrape & r i n s e container with distilled H 0 2  Wash p o r t i o n  scrape m a t e r i a l f r o m s c r e e n and walls of container o n t o f i l t e r paper  filter through Whatman #1 f i l t e r paper  Solid portion  Solid portion  (1)  (2)  • V a l u e s f o r i o n a n a l y s i s i n c o m p l e t e and low, t h e r e f o r e n o t i n c l u d e d i n computations o f i o n output.  14  filter  p a p e r was  filtrate final  was  (solid  t h a t was  procedure.  analyzed  an  cloacal  left  i n the  container after  ml  stoppered  LiGO  making a d i l u t e  volumetric flask  paper.  diluted with and  potassium  the  filtrate  in  1 ml  8.0  s l u r r y with  A 2.0 ml  Ion  evaporated  standard  the contents  w a t e r and  analyzed  For c h l o r i d e and  15  meq/LiClto  of  the  flame  The through  was f o r sodium 5 ml  of  resuspended  c o n c e n t r a t i o n s were m e a s u r e d  p h o t o m e t r y u s i n g an  and  the  Aliquots of  the  f l u i d s were d i l u t e d  to d i s s o l v e  The  lithium  the  solid  s a m p l e s d e s c r i b e d above s e r v e d as  i n the  diluted  p o r t i o n s of the  the  by  Instrumentation  bring ion concentrations within reading  photometer.  samples.  0.5%  8.  analysis, then  to  water,  cloacal  these  and  of  filtered  filtrate  to dryness  potassium  secretion  used  and  transferred  of the  salt  solution  pre-  a mortar  g r e a t e r than  photometer.  flame  a piece of  c o n t a i n i n g 75 ml  L a b o r a t o r i e s M o d e l 14 3 f l a m e gland  washing  analysis  Sodium and internal  the  These 2 d r i e d p o r t i o n s  a pH  aliquot  of d i s t i l l e d  of d i s t i l l e d c.  ml  concentrations. was  The  f e a t h e r s , i f p r e s e n t , were removed,  f l a s k s were s h a k e n o v e r n i g h t and Whatman #1  onto  g p o r t i o n o f t h e powder was  a 100  The  sample c o n s i s t e d o f  g r o u n d t o a f i n e powder w i t h  0.25  #1).  for ion content.  of the  to constant weight.  were i n d i v i d u a l l y  (solid  #2)  paper,-  t h e sample d r i e d  and  later  T h e s e s o l i d s were s c r a p e d  weighed f i l t e r  pestle  to constant weight  s t o r e d and  portion  everything  dried  internal  with range  LiC0  3  cloacal  standard  for  15  C h l o r i d e was  measured w i t h  ( R a d i o m e t e r , Copenhagen) u s i n g 20  a CMT  10  Chloride  y l a l i q u o t s of  titrator  sample  solutions. Ion o f the the  content  fish,  of the  the water content  by  K ,  Cl~.  and  69  meq/1  d.  total  of these birds meq  (61.6% body w e i g h t , n =  observed  CI / l .  Na  +  and  CI  outputs  Hughes  (1972b) t o be  These are p r o b a b l y  i n Hughes' s t u d y these  and  +  _  be  low  had  not  not  estimated by  the  CI  assigned output  L  375  y e q  as yeq Na  /  375  meq  non-salt-loaded Na /1 +  as  should predict study.  t h e mean o f t h e  obs.  other  values  the  obtain-  t o t a l CI yeq o b s . 463 ^ 5 Cl/ml  ml  ec  volume o f w a t e r l o s t  f o r by  a maximal  follows:  The  accounted  ions;  For each b i r d ,  E s t i m a t i o n of evaporative water l o s s  loss  dividing  concentrations  e.  to the weight  by  r e c e n t l y i n g e s t e d any  concentrations  I t o t a l Na  est  equal  meq/1  the  volume was  i  124  +  m i n i m a l c o n c e n t r a t i o n s as  secretion  O  and  463  volume f o r b i r d s i n t h i s  from Na  3)  and  secretion  V  Na ,  2 i o n s i n spontaneous s e c r e t i o n s from  therefore,  ed  weight  for herring  ( 1 9 7 2 b ) : 82 meq/1  g l a n d s e c r e t i o n volume was  r e p o r t e d by  birds  Hughes  from the  E s t i m a t i o n o f s e c r e t i o n volume  Salt the  calculated  f o l l o w i n g ion c o n c e n t r a t i o n s determined  (Clupea p a l a s i i ) +  f i s h was  by  (EWL)  e v a p o r a t i o n was  d u r i n g the  24  excreta, i . e . ,  assumed  hour p e r i o d t h a t  to was  16 EWL  where AW  i s the  =  AW  -  W  , ,+ cloacal  W  s.g.  change i n body w e i g h t , W  ,  , i s the  weight  C X O c L C EL X  of  the  total  cloacal excreta  weight of  salt  above and  1 g/ml  f.  gland  Discrimination nonsecretors  birds with  v a l u e was  a calculated  of  culations  between s e c r e t o r s  secretion  t h e r e was  secretion  Statistical All  i s the c a l c u l a t e d s.g. a s s u m i n g t h e volume d e t e r m i n e d  and  f r o m a l l 3 g r o u p s were a r b i t r a r i l y  c h o s e n as  distribution  3.  secretions  W  fluid.  Secretors as  and  volume -  a distinct  volumes a t  1  defined  1 ml.  This  separation  in  the  ml.  analyses  ion partitioning calculations  were done u s i n g  calculators  p r o g r a m a b l e c a l c u l a t o r 9100B) o r  and  statistics  (Monroe, H e w l e t t  a computer  (PDP  15,  cal-  Packard  Digital  Corporation). A n o n p a r a m e t r i c s t a t i s t i c a l t e s t , the Test  ( S i e g e l , 1956)  sample  chosen to determine d i f f e r e n c e s  d a t a on  birds  given  s a l t were compared w i t h  Birds  which s e c r e t e d  Values are (SEM).  U  between  groups. The  only  was  Mann W h i t n e y  presented  f i s h + s a l t and  d a t a on  birds  were compared w i t h as  the  birds  fed only  those that  means + s t a n d a r d e r r o r  of  given  fish. did  the  not. mean  17  III.  A.  Total  RESULTS  Body Water T u r n o v e r  Body w e i g h t s , TBW v o l u m e s , f o r each g u l l and s e a w a t e r 1.  Bird  and t h e mean v a l u e s f o r b o t h t h e f r e s h w a t e r drinking  regimes  (W) o f t h e b i r d s  c a n t l y between t r e a t m e n t s . r e g i m e was 76 3 + 4 6  seawater  are presented i n Table I.  weights  Body w e i g h t s  water  and TBW t u r n o v e r r a t e s  regime.  d i d not vary  Mean body w e i g h t  signifi-  f o r the f r e s h -  g compared t o 817 + 50 g f o r t h e  Mean w e i g h t  f o r both treatments  combined  was 787 + 33 g. 2.  TBW  volume  T h e r e was no d i f f e r e n c e t r e a t m e n t s whether weight. the  i n TBW volume between t h e  e x p r e s s e d as volume o r p e r c e n t o f body  The mean v a l u e o f TBW volume was 81.3 + 4.7% W  f r e s h w a t e r regime  regime.  during  and 76.9 + 2.5% W d u r i n g t h e s e a w a t e r  The mean v a l u e o f TBW volume f o r t h e combined  treat-  ments was 79.3 +2.. 8% W. 3.  TBW t u r n o v e r Rates o f t u r n o v e r v a r i e d  u a l s w i t h t.jy rates sign  2  c o n s i d e r a b l y between  v a l u e s r a n g i n g f r o m 4.5 t o 8.3 d a y s .  individTurnover  d i d n o t c o r r e l a t e w i t h body w e i g h t as d e m o n s t r a t e d by a test  (Larkin,  Figure  1974).  3 i s a representative  f u n c t i o n o f t i m e f o r one b i r d  plot  drinking  o f l o g dpm THO as a  f r e s h w a t e r and l a t e r  18 TABLE  I.  Bird #  T o t a l body w a t e r volume and t u r n o v e r r a t e s f o r Glaucous-winged G u l l s , Larus glaucescens ( + SEM) .  W (g)  TBW (ml)  TBW (% W)  1 2 3 4 5 6 7  724 880 684 892 577 707 875  552 510 580 685 515 630 840  X  763 +46  1 2 3 4  t(l/2) (days)  Flux (ml/g-day)  76.2 57.9 84.4 76.7 89.2 89.1 96.0  5.28 6.35 7.63 7.51 6.98 5.92 5.33  .072 .045 .056 .051 .063 .074 .089  616 +44  81.3 +4.7  6.42 +0.37  .064 +0.006  711 885 646 981  588 620 525 820  82.7 70.0 81.2 83.5  4.51 8.01 6.66 7.27  .091 .043 .061 .057  6 7  802 877  568 643  70.8 73.3  4.92 8.33  .071 .060  X  817 +50  627 + 42  76.9 +2.5  6.62 +0.65  .064 +0.007  787 +33  621 +29  79.3 +2.8  6.52 +0.34  .064 +0.004  Freshwater  Saltwater  c D  Combined  g u r e 3. L o s s o f t r i t i a t e d w a t e r (THO) f r o m t h e e x t r a c e l l u l a r f l u i d o f one G l a u c o u s - w i n g e d G u l l (#4) o v e r a two week p e r i o d . ( 0 ) = f r e s h w a t e r r e g i m e and (•) = sea water regime.  19a  0  J,  1  s a l t water  1 2  1  1  3  k  1 5  1 6  1 7 TIME  1 8 (DAYS)  1 9  1 10  1 ii  1 12  1 13  1 i<*  20 saltwater. turnover  The slope o f the l i n e i n d i c a t e s the r a t e o f water  (K). The data presented i n F i g u r e 3 and Table I i n d i -  cate t h a t n e i t h e r the ^2_/2'  r e q u i r e d f o r one-half the  water volume t o be r e p l a c e d , nor the water f l u x d i f f e r e n t f o r the 2 treatments.  Mean water f l u x f o r the f r e s h -  water and the seawater regimes were i d e n t i c a l , The t-jy2  f  o  r  T  B  W  (ml/g-day) were  0.064 ml/g-day.  turnover was 6.42 + 0.37 days f o r the f r e s h -  water regime compared w i t h 6.62 + 0.65 days f o r the seawater regime. 4.  A l l o m e t r i c comparisons a.  TBW volume  F i g u r e 4 i s a p l o t o f l o g TBW as a f u n c t i o n o f l o g W. The equation f o r the r e g r e s s i o n l i n e i s : l o g TBW volume = -0.25 + 1.0 l o g W (n = 19) (ml H 0) (g) 2  The  slope of t h i s l i n e was not d i f f e r e n t from 1.0, i n d i c a t i n g  t h a t t h e TBW volume i s a d i r e c t f u n c t i o n o f body weight and t h a t TBW volume may be compared among s p e c i e s as a percentage weight as i n Table I I .  The two v a l u e s f o r g u l l s  o f body  ( i n d i c a t e d by  A i n F i g u r e 4) were not i n c l u d e d i n ' the r e g r e s s i o n a n a l y s i s . point  ( t h i s study)  One  i s j u s t w i t h i n the 95% c o n f i d e n c e l i m i t s o f  the l i n e and the other p o i n t (Ruch and Hughes, 1975) i s not w i t h i n the 95% c o n f i d e n c e l i m i t s o f t h e r e g r e s s i o n l i n e .  As t h i s  a n a l y s i s and Table I I i n d i c a t e , g u l l s appear t o have a high TBW volume compared t o other b i r d s . b.  TBW turnover  The r e g r e s s i o n l i n e f o r TBW turnover on body weight i s presented i n F i g u r e 5.  The equation i s :  g u r e 4 . R e l a t i o n s h i p between t o t a l body w a t e r (TBW) volume and body w e i g h t (W). A c t u a l data values used and r e f e r e n c e s a r e l i s t e d i n T a b l e I I . The two p o i n t s marked A r e p r e s e n t t h e two G l a u c o u s - w i n g e d G u l l s and a r e n o t i n c l u d e d i n t h e r e g r e s s i o n l i n e .  TOTAL B U Y WATER V O L U e VS-  UDG Y = -0-24B7  +  BODY  1*015  V/EIGHT  * UDG X  N =  4000*  l/j.  urx>.  looo*  UDG BODY WEIGHT (G)  G O U O  TABLE I I .  Comparison o f t o t a l body water volume among a v i a n s p e c i e s .  Species  Speotyto c u n i c u l a r i a hypogaea G a l l u s domesticus  Gallus domesticus Columba l i v i a Aratinga canicularis elournirostrum G a l l u s domesticus (laying) C o t u r n i x c o t u r n i x japonica Taeniopygia castanotis G a l l u s domesticus (laying) Geococcyx c a l i f o r n i c u s Anas p l a t y r h y n c h o s H Gallus domesticus Gallus domesticus C o t u r n i x c o t u r n i x japonica Gallus domesticus Anas p l a t y r h n c h o s Gypohierax a n g o l e n s i s Gallus domesticus Larus glaucescens Larus glaucescens  a  n  W (g)  TBW (ml)  TBW (%BW)  1 5 2 8  140 3490 2506 362  58.7 1888 1362 202  41.9 54.1 54.3 55.0  Chapman & McFarland (1971) Chapman & M i h a i (1972) Ruch & Hughes (1975) LeFebvre (19 64)  1 5 5 8 5 3 7 5 4 5 4 7 1 4 6 2  313 3440 117 13.4 3530 291 2352 2600 5090 105 4640 3091 1590 4900 782 835  193 2194 72.8 8.5 2252 217 1512 1668 3273 70 3090 2121 1124 3474 622 735  61.3 61.6 61.8 63.0 63.8 64t> 64 64 64.3 66.5 66.6 68.5 70.7 70.9 79 .4 87.9  Chapman & McFarland (1971) Chapman & M i h a i (1972) Chapman & McFarland (1971) Skadhauge & Bradshaw, 1 9 7 4 ) Chapman & M i h a i (1972) Ohmart, Chapman & B l a c k ( 1 9 7 0 ) Ruch & Hughes (1975) Chapman & B l a c k (1967) Chapman & M i h a i (19 72) Chapman & McFarland (19 7 1 ) Chapman & M i h a i (1972) Ruch & Hughes (19 75) Chapman & McFarland (19 7 1 ) Chapman & M i h a i (19 72) W a l t e r (unpub.) Ruch & Hughes (19 75)  Reference  T h e s e b i r d s and v a l u e s a r e the same as those used i n F i g u r e 4.  ID  Ohmart e t a l . r e p o r t e d TBW volume = 64% W b u t t h e i r d a t a on body weight and TBW volume i n d i c a t e the v a l u e s h o u l d be 75% W. c M a i n t a i n e d on a s a l t w a t e r regime (87% seawater).  ro  23  F i g u r e 5. R e l a t i o n s h i p between t o t a l body w a t e r (TBW) t u r n o v e r r a t e and body w e i g h t (W) f o r a v a r i e t y o f avian species. The p o i n t f o r G l a u c o u s - w i n g e d G u l l s A determined i n t h i s study i s not i n c l u d e d i n the r e g r e s s i o n l i n e . V a l u e s f o r t u r n o v e r were d e t e r m i n e d by THO d i s a p p e a r a n c e o r by t o t a l w a t e r budgets. S p e c i e s and r e f e r e n c e s a r e l i s t e d i n o r d e r f r o m l e a s t t o g r e a t e s t body w e i g h t : Z e b r a F i n c h , T a e n i o p y g i a c a s t a n o t i s (2) (Skadhauge & Bradshaw, 19 7 4 ) ; I n c a Dove, S c a r d a f e l l a i n c a (27) ( M c M i l l e n & T r o s t , 1966); C o w b i r d , M o l o t h r u s a t e r o b s c u r u s (9) L u s t i c , 1970) ; C o t u r n i x Q u a i l , C o t u r n i x c o t u r n i x j a p o n i c a (10) (Chapman & M c F a r l a n d , 1971); W h i t e - w i n g e d Dove, Z e n a i d a a s i a t i c a a s i a t i c a (17) ( M c M i l l e n & T r o s t , 1966); B u r r o w i n g Owl, S p e o t y t o c u n i c u l a r i a h y p o g a e a (1) (Chapman & M c F a r l a n d , 1971); R o a d r u n n e r , G o c o c c y x c a l i f o r n i c u s (3) (Ohmart, Chapman & M c F a r l a n d , 1970) ; P e t z Conure, A r a t i n g a c a n c u l a r i s e l o u r n i r o s t r u m (1) (Chapman & M c F a r l a n d , 1971); G l a u c o u s - w i n g e d G u l l , L a r u s g l a u c e s c e n s (;7):(present study); V u l t u r i n e F i s h E a g l e , G y p o h i e r a z a n g o l e n s i s (1) (Chapman & M c F a r l a n d , 1971); White Leghorn C h i c k e n , G a l l u s domesticus ( 5 ) (Chapman & B l a c k , 1967); n o n l a y i n g Rock C o r n i s h Hen, Rock C o r n i s h R o o s t e r G a l l u s d o m e s t i c u s (4) (Chapman & M i h a i , 19 7 2 ) . f  23a  TOTAL BODY WATER TLFNOVER RATE V5» BODY WEIGHT LOG Y = -0.3393  10.  jjCX)-  + 0*7517  * UDG X  1000-  LOG BODY WEIGHT CG)  N = 13  GOOD.  24 log  turnover  (ml The  value  B.  Salt 1.  and  the  fish-fed  of Na , +  K  and  +  was  the  gland The  the  The  CI  fell  w i t h i n the  i n Table  less  excreted  than +  and  calculated  K  CI +  2.  8.0  the  total  gland, both Thirty-eight of  the  of  Distribution Figure  of  ml  v i a the c l o a c a ; two  was  e x c r e t e d v i a the  6 i s a bar  percent  1.7  ml  obas  cloaca.  graph showing the  e x c r e t i o n f o r each cloacal  from the  f o r the  of ion excretion.  fractions, of the  relative  i o n and w a t e r and  the  s o d i u m , 6%  c h l o r i d e were e x c r e t e d v i a t h e  the water e x c r e t e d v i a these  C.  lost  groups.  were e x c r e t e d v i a  volume o f w a t e r n e c e s s a r y  fluid  the  d i f f e r e n c e among  the o t h e r  c l o a c a ; most o f t h e  salt  I I I f o r each o f  s e r v e d e x t r a r e n a l s e c r e t i o n f o r a l l t h e b i r d s was compared t o  range  from the  only s i g n i f i c a n t  same amount o f N a  and  collected  amount o f CI  birds excreted  Approximately  cloaca.  study  output.  treatments.  treatments  salt  13)  Cloaca  fluid  yeq  the  the  in this  c l o a c a are presented  experimental  (n =  (g)  gulls  and  and  Total gland  log W  body w e i g h t .  Gland Ion  + 0.75  2  f o r the  p r e d i c t e d by  = -0.40  H 0/day)  two  total  percentage  from the  salt  cloacal excretion.  o f the potassium salt  r o u t e s was  Ion P a r t i t i o n i n g Between C l o a c a l F l u i d Portions  gland.  Only  v i a the  and  Solid  salt  and 15%  58% of  gland.  25  TABLE I I I .  I o n c o n t e n t o f s a l t g l a n d s e c r e t i o n and c l o a c a l e x c r e t i o n c o l l e c t e d o v e r 24 hours from G l a u c o u s - w i n g e d G u l l s , L a r u s glaucescens given e i t h e r f i s h , f i s h + s a l t , o r s a l t only. The v a l u e s a r e p r e s e n t e d as means + SEM.  Salt gland  T o t a l i o n c o n t e n t (yeq) Cloacal Cloacal Cloacal fluid solid fluid & solid  S a l t Gland & cloacal  648+280  284+ 86  324+ 55  608+112  1256+295  642+252  766+538  305+ 88  997+531  1639+541  only  688+252  369+228  118+ 22  487+250  1175+ 25  f i s h only  93+ 55  462+105  807+142  1126+253  1361+182  fish  +  58+ 20  597+270  645+178  1247+444  1305+449  salt  only  71+ 46  '894+124  400+4.5  1294+120  1364+165  f i s h only  927+408  255+169  255+169  1153+417  763+288  .1009+688*  1009+668*  775+275  1551+218*  1551+218*  Na  +  ^ a f i s h only fish + salt  K  salt  b  +  salt  Cl"  fish + salt  salt  only  d  2326+ 46  a  n=7, s a l t  i n p u t was 3089+460 yeq N a , 4703+700 yeq K ,  2619+ yeq  b  n=4, s a l t  i n p u t was 10740+152 yeq N a ,  10095+67 yeq C l ~ .  c  n=2. s a l t 'input was 3200 yeq N a , 5000 yeq K , 8200 yeq C l ~ .  +  +  +  n=2 * p<0.05, Mann Whitney U T e s t . Ion e x c r e t i o n from b i r d s f e d o n l y f e d f i s h + s a l t and i n d e p e n d e n t l y  +  4941+138 yeq  K , +  Cl .  +  d  f i s h was compared t o t h a t o f t h e b i r d s t o those f e d s a l t o n l y .  26  F i g u r e 6. The p a r t i t i o n i n g o f i o n s and w a t e r i n 24 h o u r s a l t g l a n d and c l o a c a l c o l l e c t i o n s f r o m G l a u c o u s w i n g e d G u l l s , L a r u s g l a u c e s c e n s p r e s e n t e d as p e r c e n t a g e s o f t o t a l i o n and w a t e r e x c r e t i o n . E x c r e t i o n v i a t h e s a l t g l a n d i s r e p r e s e n t e d by t h e s t r i p e d b a r s . C l o a c a l e x c r e t i o n i s d i v i d e d i n t o two p o r t i o n s ; f l u i d i s r e p r e s e n t e d by t h e w h i t e p o r t i o n o f t h e b a r s and s o l i d i s r e p r e s e n t e d by t h e s t r i p e d p o r t i o n o f t h e b a r s . V e r t i c a l l i n e s r e p r e s e n t + 1 SEM. Sample s i z e was 11 f o r t h e s o d i u m , p o t a s s i u m and w a t e r a n a l y s e s and was 6 f o r t h e c h l o r i d e a n a l y s i s .  SODIUM  POTASSIUM  CHLORIDE  WATER  27 Only the c a t i o n s were found i n both the f l u i d s o l i d p o r t i o n s of the c l o a c a l samples.  C h l o r i d e was  and found  only i n the f l u i d p o r t i o n . Although the r e l a t i v e d i s t r i b u t i o n o f N a  +  and K  tween the two p o r t i o n s v a r i e d , the s o l i d s contained of the t o t a l c a t i o n s i n the c l o a c a l e x c r e t a . of the c o n c e n t r a t i o n s  The  +  be-  nearly h a l f  logarithims  o f sodium and potassium i n the f l u i d  were p l o t t e d a g a i n s t the l o g a r i t h i m o f t h e i r r e s p e c t i v e concentrantions was  (yeq/g) i n the s o l i d p o r t i o n  (Figure 7a & 7b).  no r e l a t i o n s h i p between the two sodium c o n c e n t r a t i o n s  There but  some i n d i c a t i o n o f a l i n e a r r e l a t i o n s h i p between the two potassium c o n c e n t r a t i o n s .  The l o g a r i t h i m o f the sum o f the  c a t i o n s i n each f r a c t i o n was l i n e a r r e l a t i o n s h i p was  a l s o p l o t t e d (Figure 7c) and a  obtained.  A s i g n i f i c a n t l y higher  chloride concentration  was  observed i n the s a l t - o n l y b i r d s compared to the f i s h - o n l y b i r d s (Table I V ) .  T h i s was  concentrations  the only s i g n i f i c a n t d i f f e r e n c e i n i o n  i n the c l o a c a l f l u i d .  The weight o f the c l o a c a l s o l i d m a t e r i a l excreted the s a l t group was group.  about 1/3  by  the weight e x c r e t e d by the f i s h  However, the amount o f potassium per u n i t weight o f  s o l i d i s s i g n i f i c a n t l y g r e a t e r i n the s a l t group compared t o the f i s h  group. For a l l regimes, more K  +  than N a  the f l u i d and s o l i d p o r t i o n s ; the N a / K +  higher  +  +  was  found i n both  r a t i o seemed to be  i n the f l u i d than i n the s o l i d p o r t i o n .  g u r e 7 . R e l a t i o n s h i p between c a t i o n c o n c e n t r a t i o n s i n t h e f l u i d p o r t i o n and s o l i d p o r t i o n o f t h e cloacal excretion. P l o t s (a) and (b) a r e t h e r e l a t i o n s h i p between N a and K respectively in t h e f l u i d and s o l i d p o r t i o n s . I n (c) t h e sum o f Na and K i n each f r a c t i o n i s p l o t t e d . +  +  +  +  28a  FLUID NA • K (MEQ/L)  29  TABLE IV.  Weight and i o n c o n c e n t r a t i o n o f f l u i d and s o l i d p o r t i o n s o f c l o a c a l e x c r e t a c o l l e c t e d o v e r 24 hours from G l a u c o u s - w i n g e d G u l l s , Larus glaucescens given e i t h e r f i s h , f i s h + s a l t , o r s a l t o n l y . T h e v a l u e s a r e p r e s e n t e d as means + SEM.  FLUID FRACTION Weight,g  fish n=7 fish + salt n=4 salt n=2  6.6 +0.7  Na  T  Ion C o n c e n t r a t i o n , K+  meg/ml Cl"  Na / K +  42.7+13.1  68.1+13.3  37. 1+14.3  0.64+0.13  +4.2  50.8+20.6  56.6+ 8.7  55. 8+21.3  0.94+0.37  8.46+0.2  43.0+26.0  10.1  106  +17  *  184  +37  0.46+0.32  SOLID FRACTION Weight,g Na  Ion C o n t e n t , K+  T  yeq/g  Na /K +  Cl  +  _  fish n=7  1.83+0.21  179  +30  439  +54  0  0.43+0.07  fish + salt n=4  1.36+0.15  236  +83  524  +184  0  0.51+0.13  salt n=2 -•  0.45+0.05* 272  +76  903  +99*  0  0.30+0.05  *p  < 0.05, Mann Whitney U T e s t  Ion e x c r e t i o n from b i r d s f e d o n l y f i s h was compared t o t h a t o f t h e b i r d s f e d f i s h + s a l t and i n d e p e n d e n t l y t o t h o s e f e d s a l t o n l y .  30 D.  Evaporative  Water  Evaporative given  only  + salt. higher  salt  Loss  water l o s s  than  i n EWL  ambient temperature  f a c t o r s which are  E.  C o m p a r i s o n Between S a l t and Nonsecretors  in  the  only  cloacal  t h e r e were no trations groups  (Table V I I ) .  nonsecretors tion  significant  than  the  The  identical  f o r the  two  have l e s s  ion per  gram s o l i d  water l o s s be  f o r the  g r e a t e r than  this  d i f f e r e n c e was  two  of Na  fluid fluid  than  s e c r e t o r s was  not  (Table  nonsecretors  g r o u p s and and  +  cloacal  groups, but  f o r the  humidity  CI  .  secretion  Similarly,  fractions  and  a tendency a greater  nonsecretors  the  secretors.  significant.  for  +  8.2  (39.1  ml  the por-  appear  seem t o Evaporative  and  + 2.2  two  solid  ion concentrations  57.8  concen-  o f the  the  nonsecretors  is  significant differences  However, t h e r e was  t o have a s m a l l e r  fish  somewhat  d i f f e r e n c e s i n the weights or  or s o l i d  secretors.  or  EWL.  s e c r e t o r s and  output  birds  Secretors  f o r these  total  fluid  Gland  T h e r e a r e no  i o n output  i n the  f o r the  despite  to increase  f o r the  VI.  i n c r e a s e d the  less  lower r e l a t i v e  expected  i o n output  i n Table  occurred  and  V),  presented  was  f o r the b i r d s t h a t r e c e i v e d f i s h  This decrease  The  (EWL)  tended  ml),  but  to  31  TABLE V.  E v a p o r a t i v e water l o s s d u r i n g 24-hours from Glaucous-winged G u l l s , Larus glaucescens f e d f i s h , f i s h and s a l t o r s a l t o n l y . Data v a l u e s a r e means + SEM.  EWL, g  Fish n=7 Fish n=4 Salt n=2  & Salt  T e m p e r a t u r e , °C  Relative Humidity  41.9+ 5. 6  22  + 0.6  72+0.9  58.0+11. 0  25  + 0.8  72+0.9  28. 0+0.5  70+0.3  14.1+ 6. 8  *  Evaporative water loss c a l c u l a t e d AW, . , - (W. . , + W ,. ) bird total salt cloacal gland loss secretion  by a s s u m i n g EWL =  p<0.05, Mann W h i t n e y U T e s t D a t a f r o m b i r d s f e d f i s h o n l y were compared t o d a t a f r o m b i r d s f e d f i s h and s a l t and i n d e p e n d e n t l y t o t h o s e f e d s a l t only.  32  TABLE V I . Ion c o n t e n t o f s a l t gland and c l o a c a l i o n e x c r e t i o n : amount o f i o n (peq) e x c r e t e d p e r 24 hours by s e c r e t i n g - and n o n s e c r e t i n g Glaucous-winged G u l l s , L a r u s g l a u c e s c e n s . The v a l u e s a r e means + SEM. 3  T o t a l i o n c o n t e n t (yeq) Cloacal Cloacal solids Fluid & Solid  Salt gland  Cloacal fluids  S a l t Gland & cloacal  1102+205  587+361  310+65  883+348  1985+274  98+ 41  263+106  326+ 61  589+131  687+190  secretors n=6  140+ 53  610+180  739+153  1352+266  1434+254  nonsecretors n=5  7.8+3.8  392+105  759+153  1151+570  1159+289  1556+347"  561+292  561+292  1988+352'  216+ 9 8  249+142 ~  Na secretors n=6 nonsecretors n=5  K  Cl secretors n=5 nonsecretors n=4 p < 0.05; a  b c  d  d  249+142'  318+222  v  p < 0.005 (Mann Whitney U T e s t )  S e c r e t i n g g u l l s were d e f i n e d as those t h a t s e c r e t e d a t l e a s t 1 ml o f f l u i d i n 24 hours. Three o f t h e 7 b i r d s t h a t r e c e i v e d o n l y f i s h were s e c r e t o r s and 3 o f t h e 4 b i r d s t h a t r e c e i v e d f i s h and s a l t s were s e c r e t o r s . . n=4 T  n=3 n=2  33  TABLE V I I .  Weight and i o n c o n c e n t r a t i o n s o f f l u i d and s o l i d p o r t i o n s o f c l o a c a l e x c r e t a c o l l e c t e d o v e r 24 hours from s e c r e t i n g and n o n s e c r e t i n g Glaucous-winged G u l l s , L a r u s g l a u c e s c e n s . 3  FLUID FRACTION Ion  Weight,g Na  +  Na /K  C o n c e n t r a t i o n , meq/1 K Cl"  +  +  +  secretors n=6  9.5 +2.8  48.0+13.5  63.0+ 7.7  41.1+ 9. 9  nonsecretors n=5  5.9+0.4  42.8+18.6  65.1+18.5  41.4+25. 8°  b  0 .83+0.24 0 .71+0.2 3  SOLID FRACTION Weight,g  Ion P e r U n i t K Na +  +  secretors n=6  1.41+0.17  231  nonsecretors n=5  1.95+0.23  162 +18  +60  545  Weight, yeq/g Cl~ +112  382 +70  Na /K +  +  0  0 .47+0.16  0  0 .45+0.06  S e c r e t i n g g u l l s were d e f i n e d as t h o s e t h a t s e c r e t e d a t l e a s t 1 ml o f f l u i d i n 24 h o u r s . Three o f t h e 7 b i r d s t h a t r e c e i v e d o n l y f i s h were s e c r e t o r s , and 3 o f t h e 4 b i r d s t h a t r e c e i v e d f i s h and s a l t were s e c r e t o r s . b  n=5  C  n=4  34  IV. A.  DISCUSSION  T o t a l Body Water Volume and T u r n o v e r R a t e TBW volume i s t h e same i n f r e s h w a t e r  adapted g u l l s the  (Table I ) .  gulls' adaptation The v a l u e  this  study  This observation i s supportive of  to chronic ingestion of hypertonic  o f TBW volume  i s high  compared t o t h o s e o f o t h e r b i r d s  f o r G l a u c o u s - w i n g e d g u l l s b y Ruch  marine b i r d s s i n c e a l a r g e r e l a t i v e  body  impact o f a s a l t fluids.  fluid  l o a d on t h e s a l t  (See A p p e n d i x I I I )  1000 m i l l i o s m o l a r s o l u t i o n (Appendix I I I ) t o r a i s e  reservoir that  the  volume w o u l d b u f f e r  concentrations of the  ( e . g . , s e a w a t e r ) was c a l c u l a t e d  t h e o s m o l a l i t y o f t h e body  fluids  from  i f t h e TBW volume i s 62%  raise  Similarly,  t h e o s m o l a r i t y o f t h e body  fluids to  t h e l a r g e TBW volume may p r o v i d e a  m i g h t be i n n e g a t i v e w a t e r b a l a n c e  i t s t i s s u e s become s e v e r e l y d e h y d r a t e d .  adaptive  served  significance to  f o r p e r i o d s d u r i n g which water i s n o t a v a i l a b l e so  a bird  before  (19 7 5 ) .  I f TBW volume i s 84% body w e i g h t , t h e same volume  of sea water w i l l 348 mosm/1.]  & Hughes  [ F o r example, 50 ml o f an  300 t o 401 mosm/1 i n an 800 gram b i r d body w e i g h t .  (Table I I ,  t h a n t h e 87.9% body w e i g h t  The l a r g e r TBW volume may be o f a d a p t i v e  the  fluid.  (79% body w e i g h t ) o b t a i n e d i n  mean = 62% body w e i g h t ) b u t l e s s obtained  and s e a w a t e r  f o r some  time  An example o f  v a l u e o f a l a r g e t o t a l body w a t e r volume i s o b -  among t h e a n u r a n a m p h i b i a n s . T h e s e o r g a n i s m s a r e h i g h l y  35 s u s c e p t a b l e t o d e h y d r a t i o n and  have TBW  volumes r a n g i n g  77.5-80.1% body w e i g h t when n o r m a l l y h y d r a t e d Svihla,  1943).  pelagic  avian  large in  TBW  TBW  species  w o u l d be  of  interest  decreased drinking s e a w a t e r as  rates, and  ^-^/2  v  Fletcher  rates  i n ducks  rates  weight  and  Holmes  a  l  u  e  s  are a  r  e  4  -  is lost  smaller  total  (1968)  and  report  (Anas p l a t y r h y n c h o s )  given  converted to weight-related  turnover  2  a n <  ^  4  -  days f o r the  5  respectively.  i n the  The  turnover rates birds  and  w a t e r volume as  the  freshwater  discrepancy  due  to  in  l o w e r body  assumption of  a percentage of  f o r d u c k s i n a c c o r d a n c e w i t h Ruch & Hughes  (Table  a  body  (19 75)  II) . There are  drinking  species  some s p e c i e s  s a l t water.  centration  Drinking  of passerine rates  1968;  McNabb, 1969;  r e s p o n s e have b e e n f o u n d : 1) increasing  as  birds  that  a function  of  tolerate salt  con-  i n d r i n k i n g w a t e r have b e e n measured f o r a number  (Bartholomew & Cade, 1963;  Willoughby,  salinity rate  an  MacMillen  & Snelling,  Poulson,  1969).  increase  in drinking  of  1966;  Three types rate  of  with  u n t i l a c r i t i c a l maximum s a l i n i t y i s reached,rat which  point  drinking  2)  change i n d r i n k i n g  no  same i n f r e s h w a t e r  However,  weights of saline-maintained slightly  live  f r e s h water.  s a l i n e maintained birds  drinking  the  compared t o d u c k s g i v e n  water intakes  the  to determine i f  environment.  sea w a t e r adapted g u l l s .  when t h e  and  phenomenon among b i r d s w h i c h  T u r n o v e r r a t e o f w a t e r was  60%  (Thorson &  volume measurements o f o t h e r c o a s t a l  volume i s a g e n e r a l  a marine  from  falls  sharply rate with  (e.g.,  House F i n c h ,  increasing  salinity  Bobwhite); (e.g.,  California no  Quail,  Gambel's Q u a i l ) ;  change f r o m a v e r y h i g h  Savannah S p a r r o w ) . the  more s a l t  bel's  Quail,  drinking  rates  drinking  water.  species rates  of  rate  gull.  solutions  water to  1.0  as  studies  M NaCl.  solutions  solutions  Rare  The  drinking  from d i s t i l l e d about  living  Quail,  The  articilla,  1/3  from  the  original  a more p e l a g i c  randomly o f f e r e d  previously  drinking  from d i s t i l l e d water t o slightly 0.5  as  drinking  adapted to sea  solutions  2.0  ranging  M NaCl.  rapidly to  as 1.0  of the  these  M  in  Drinking  concentration  M NaCl.  Laughing Gulls  The  fact  The of  drinking the  that  remained constant  Harriman Gulls,  Herring  Gulls.  were  concentration  increased  to sea  rate  did  water  a more  only to con-  drop.off'  increased  drinking  through  rate  r a t e dropped  solutions  the  birds  NaCl  w a t e r and  solution concentration  ions.  for  drinking  than the  M NaCl which i s approximately equivalent  centrations  0.5  the  species  three  drinking  constant  w a t e r t o a b o u t 0.2  of  the  distilled  were i n c r e a s i n g l y c o n c e n t r a t e d .  b i r d s were n o t  of  offered  (1967) d i d a s i m i l a r e x p e r i m e n t w i t h y o u n g L a u g h i n g Larus  Gam-  salinity  argentatus  r a t e was  in  constant  (1966) m e a s u r e d  i n concentration  or  (e.g.,  have a l s o b e e n done w i t h  G u l l s , Larus  ranging  then dropped to the  (California  f l u c t u a t i o n s i n the  Harrimvan and  drinking  and  of  increase  rate  S a v a n n a h Sparrow) t e n d t o h a v e  of n i a i v e Herring  offered  a slight  those species  environments  i n face  Drinking  3)  f r e s h water d r i n k i n g  I t appears t h a t  stressed and  and  rate of  from the  concentrated  36A d r i n k i n g s o l u t i o n than t h a t preted of  by H a r r i m a n  these  o f the Herring  G u l l s was  (1967) t o be due t o t h e h a b i t a t  two s p e c i e s .  A third  drinking rate  inter-  difference  study with  Larus  g l a u c e s c e n s , t h e same s p e c i e s  used i n t h e p r e s e n t  reports  t o sea water, the d r i n k i n g  of  that  gulls  after  adaptation  receiving f u l l  strength  tap water  drinking rates  (Hughes, p e r s o n a l  t h e y were  communication).  i n Hughes' s t u d y were 0.098 m l / g body  The weight-  day  a n d 0.054 m l / g body w e i g h t - d a y when t h e g u l l s were  ing  t a p w a t e r and s e a w a t e r r e s p e c t i v e l y .  turnover  rate  i n the present  at  least  Harriman  one s p e c i e s  same d r i n k i n g  water as w h i l e  ing  rate  These c o n t r a d i c t i o n s  (1967) h a s shown t h a t of gull,  drinking d i s t i l l e d  50% when t h e b i r d s  or  water.  the turnover  function of handling composition. apparent  Further  discrepancy.  rate  i n the present  rather  However,  to  drink-  s e a w a t e r compared t o  I t i s possible  i n Hughes' s t u d y were o v e r - d r i n k i n g  that  t o have t h e  (Hughes) a p p e a r s t o d e c r e a s e  are drinking  when t h e y a r e d r i n k i n g t a p w a t e r . gulls  n e e d t o be  i t i s possible f o r  Larus a r t i c i l l a ,  i n Glaucous-winged G u l l s  nearly  However, t h e TBW  r a t e w h i l e d r i n k i n g NaCl s o l u t i o n s e q u i v a l e n t  sea  by  drink-  s t u d y was 0.064 m l / g w e i g h t - d a y  under both d r i n k i n g regimes. explained.  rate  s e a water dropped t o about  h a l f o f t h e d r i n k i n g r a t e o f t h e same b i r d s w h i l e receiving  study,  that the  w h i l e on t a p w a t e r study  i s actually a  than the a c t u a l d r i n k i n g  water  experiments a r e needed t o r e s o l v e  this  36B Thus, i t appears i n n e i t h e r p e l a g i c g u l l s , ducks, nor probably i n s a l t adapted p a s s e r i n e s , water turnover  does the r a t e o f  change w i t h d r i n k i n g regime.  U n l i k e the ducks,  however, body, weight changes among the g u l l s were random with r e s p e c t t o d r i n k i n g regime.  This i n d i c a t e s that i n contrast  to ducks, g u l l s are able t o maintain weight and normal hydrat i o n w h i l e d r i n k i n g sea water. The  r a t e o f turnover  water turnover Therefore,  hypertonic  r a t e s i n other  t h i s aspect  i n t h i s species  i n g u l l s i s no d i f f e r e n t avian s p e c i e s  from  (Figure 4 ) .  o f water metabolism i s not m o d i f i e d  as a consequence o f i t s a b i l i t y t o i n g e s t  s a l t s o l u t i o n s without becoming dehydrated.  These data i n d i c a t e t h a t Glaucous-winged G u l l s are h i g h l y adapted t o w i t h s t a n d p e r i o d s when only  s a l i n e water i s  a v a i l a b l e s i n c e they are able to maintain constant even when i o n f l u x i n c r e a s e s .  water  One may assume t h a t there  flux i s no  c o n t i n u a l accumulation o f ions i n sea water maintained b i r d s on the b a s i s o f plasma i o n l e v e l s ; sodium l e v e l s are s l i g h t l y greater  i n s a l t adapted b i r d s as compared t o f r e s h water b i r d s  (157  v s . 151 meq/1), b u t r e m a i n c o n s t a n t  1970). tions  Since  the i n f l u x  Water i n f l u x food,  water.  (mixed f e c a l  evaporative  achieved  and w a t e r b a l a n c e a r e c l o s e l y l i n k e d  water  by r e d i s t r i b u t i o n gland  of salt  e x c r e t a were m e a s u r e d o v e r s a l t water adapted  B.  T h e r e were v e r y groups  with  cloacal  gland  secretion,  o v e r a l l water  flux re-  changes i n i o n e x c r e t i o n  of excreted  ions  and w a t e r  excretions. Therefore gland  t h e volume  s e c r e t i o n and c l o a c a l  24 h o u r i n t e r v a l s i n f r e s h and  gulls.  I o n s and W a t e r i n S a l t Excretion  experimental  Since  i t i s probable that  ion concentration  includes  and u r i n a r y ) , s a l t  losses.  between c l o a c a l and s a l t and  Water e f f l u x  Gland S e c r e t i o n  few s i g n i f i c a n t  and C l o a c a l  d i f f e r e n c e s among t h e  f o r the measured p a r a m e t e r s .  Differences  t h a t may have e x i s t e d c o u l d h a v e been o b s c u r e d by s m a l l sizes  and e x t r e m e l y  variation  large variances  i n cloacal excretion  however, i n t h i s experimental  study  design  there  within  among b i r d s  groups.  were a l s o s e v e r a l  that contributed  During t h i s  within  groups.  most o b v i o u s c o n t r i b u t i o n t o v a r i a n c e  sample c o l l e c t i o n .  high;  f a c t o r s i n the  to the variance  g r o u p was t h e f o u r h o u r p e r i o d b e t w e e n f e e d i n g of  sample  Individual  i s generally  g r o u p s and d e c r e a s e d t h e d i f f e r e n c e s between The  func-  regulated.  c o n s i s t s o f water drunk, water i n g e s t e d  mains c o n s t a n t , are  (Hughes,  and e f f l u x o f b o t h a r e c a r e f u l l y  and m e t a b o l i c  water l o s s e s and  salt  over time  within  and  each  beginning  t i m e , d r i n k i n g r a t e was n o t  38 controlled digestion  o r measured.  and  excretion.  Indeed,since  c o l l e c t e d from the  (Hughes, 19 7 0 ) , secretion during occur the  motility  and  salt  immediately  this  subsequent  o r more o f an  gland  within  associated with  bird  b i r d weights  amounts o f  the  1 hour a f t e r  the  the  fish  yeq  or  ion  hour can  loading  extrarenal meal  occurred  Although s e c r e t i o n probably  e x p r e s s e d as  did  to note  that  yeq/100 g body  each treatment s i n c e  the  fish  weights  varied.  to the  lack of  ion or  fluid  t h a t were f e d f i s h discussion w i l l  24  NaCl load  c o l l e c t i o n began, i t i s important  i o n load per  Due  50%  4 hour p e r i o d .  before  during  p o r t i o n o f the  i t i s p r o b a b l e t h a t much o f  weight v a r i e d w i t h i n and  Thus, a v a r y i n g  c o u l d have been e x c r e t e d  study p e r i o d . be  i n gut  r a t e would have caused d i f f e r e n c e s i n e l e c t r o l y t e  absorption load  Differences  can  d i f f e r e n c e s between g r o u p s ,  lost be  consider  from the  combined. the  11  two  groups o f  Therefore,  fish-fed  gulls  the  gulls  subsequent as  a single  group. One the  salt  induced  gland by  excreted  extremely  the salt  s t u d y was  under c o n d i t i o n s  a large salt  by  removed by  total  objective of this  fish-fed gland  important  load.  secretion  fraction  p o t a s s i u m removed was  although r e l a t i v e l y  small,  the  role  i n w h i c h i o n e x c r e t i o n was Of  gulls  to quantify  the  39%  total  and  (Figure  of the secreted  58% 6)  chloride  representing  the  does r e p r e s e n t  not  r e s p e c t i v e l y were  total. by  s o d i u m and  of  Only  7%  of  salt  gland  an the which,  a contribution  to  39 potassium removal. results.  Hughes  24 h o u r s  O t h e r i n v e s t i g a t o r s have o b t a i n e d  (1972a) c o l l e c t e d s p o n t a n e o u s s e c r e t i o n s f o r  from Glaucous-winged  Gulls  p o t a s s i u m and c h l o r i d e s e c r e t e d Continual  cloacal excretion  The  percentages of t o t a l  slightly  loaded  birds  gland  an i m p o r t a n t  f r a c t i o n of the  gland.  o f the g u l l s i n t h i s  f o r which c l o a c a l e x c r e t i o n  that  long  for salt  and n a s a l  period.  excretion  study are  d i f f e r e n t from percentages r e p o r t e d  a l . (1958) r e p o r t e d  Terns  s o d i u m and c h l o r i d e  were c o l l e c t e d o v e r a r e l a t i v e l y et  secretion  Schmidt-Neilsen  48%, 10% and 49% o f t h e t o t a l  s o d i u m , p o t a s s i u m and c h l o r i d e r e s p e c t i v e l y e x c r e t e d h o u r s were removed v i a t h e s a l t rant  +  and c l o a c a l e x c r e t i o n s  fed salt-loaded Herring of  t h e sodium e x c r e t e d  f r o m two l a b o r a t o r i e s 1969)  gland  (54 meq N a C l and 4 meq K ) .  extrarenal  excretion  0.75% o f t h e K  low  value  were h i g h  excreted  relative  the ducks' p l a n t relative  previously  and f o u n d 66% gland.  I f data  from s a l i n e m a i n t a i n e d  and  of  from  (Holmes e_t a l , 19 6 8 and Hughes & Ruch,  c o m b i n e d , one c a n c a l c u l a t e t h a t  +  argentatus, by t h e s a l t  are  forK  cormo-  (1970) c o l l e c t e d  f o r 3-4 h o u r s  was s e c r e t e d  in 8  i n a salt-loaded  Douglas  G u l l s , Larus  on s p o n t a n e o u s s a l t  +  study.  (Hughes, 1972b) consumming known  must be v i a t h e s a l t  removed v i a t h e s a l t only  were t h e same as i n t h i s  both suggest that  sodium e x c r e t i o n  and t h e amounts o f sodium,  c o l l e c t e d from growing  (Hughes, 1968) and K i t t i w a k e s amounts o f f o o d  similar  occurred  to other  diet since to those  6 7.4% o f t h e N a v i a the s a l t  studies  excreted  gland.  The  may be i n d i c a t i v e  c l o a c a l values  f o r the g u l l s .  +  ducks  of K  +  excretion  40 These r e s u l t s f o r v a r i o u s marine b i r d s are a l l very d i f f e r e n t from those obtained  f o r fed R e d - t a i l e d Hawks, Buteo  jamaicensis  Hav/ks do have s a l t glands,  (Johnson, 1969).  but  during a 24 hour c o l l e c t i o n p e r i o d only 3% of the t o t a l sodium excreted was  contained  i n the s a l t gland  secretions.  One  i n f e r from these data t h a t i n c o n t r a s t t o the hawks, the use the s a l t gland K  +  f o r r o u t i n e Na  and  +  balance of the excreted  c l o a c a l samples, approximately 61% 94%  of the K  +  load.  ions were contained of the Na , +  45%  i n the  of the CI ,  excreted by the b i r d s i n t h i s study.  l a r g e p o r t i o n of the measured c a t i o n s was cipitated solids. pressure  gulls  e x c r e t i o n and some  e x c r e t i o n as w e l l as e x c r e t i o n subsequent to a s a l t The  and  CI  of the c l o a c a l f l u i d , and thus r e p r e s e n t roughly  A  found with the  These ions do not c o n t r i b u t e to the  of c l o a c a l osmotic pressure  can  pre-  osmotic  a reduction  e q u i v a l e n t t o 87 mosm/1.  T h i s important c o n t r i b u t i o n t o the t o t a l i o n e x c r e t i o n i s r a r e l y considered  although s i m i l a r p r o p o r t i o n s  been r e p o r t e d  f o r Kittiwakes  (Johnson, 1969), and r o o s t e r l a t t e r s t u d i e s , NH*  was  of bound c a t i o n s have  (Hughes, 1972b), R e d - t a i l e d Hawks (McNabb et a l . , 1973).  In the  measured i n the c l o a c a l e x c r e t i o n  found to be the major c a t i o n i n the f l u i d p o r t i o n . suggests t h a t the bound Na  +  and K  +  and  This  i s an important means of  a l l o w i n g s u f f i c i e n t osmotic space i n the c l o a c a l f l u i d f o r n i t r o g e n or a c i d e x c r e t i o n as ammonium. Hughes (19 72b) solid portion.  observed some c h l o r i d e bound to the  None was  detected  two  i n t h i s study, but t h i s i s  41 p r o b a b l y due zation  to  the  procedure beyond the  method u s e d r a t h e r It  primary  material  t h a n an  is difficult  ion excretion The  d i l u t i o n of  patterns  i n the  ever,  the  tion,  their capacity  than that  fed b i r d s  of  the  birds  fluid and  weight of  not  i n the  solids  the  to bind  III)  chloride  feeding  given  a  amount o f  on fish.  solid  p r o b a b l y due rectum.  uric acid  c l o a c a l ions  solubili-  chloride.  e f f e c t of  from the  more t o t a l  the  were n o t  (Table  s o l i d waste  s i g n i f i c a n t , the  i n the  and  to  I f , how-  urate  w o u l d be  excre-  greater  t e n d e d t o be  7).  fluid  toward h i g h e r  loss  low.  among t h e  higher  and  and  an  the  more  concentrated  than i n the total  total  possible  in this was  salt  cloacal solids.  fed  cation  cations/unit to  judge  ion concentrations  is a result  study.  observed  i n the  3 groups w i t h  Although these  which suggests  t e m p e r a t u r e was  birds  I t i s not  other circumstances  being unusually  group g i v e n o n l y  u n i t weight of  2 fasted  cloacal  (Figure  e v a p o r a t i v e water  cantly  absence o f  2 birds  A significant difference  same day,  l i m i t s of  i s a c o r r e l a t i o n between t h e  whether t h i s t r e n d  the  uric acid  a d e c r e a s e i n the  sodium a l s o  portion  there  f a s t i n g or  the  unfed-birds.  concentration  of  only  t e n d t o have more i o n p e r  Potassium but in  actual  was  had  Although not did  detection  cloacal excreta  a d e c r e a s e d amount o f  by  to evaluate as  difference  Cl  2 birds  environmental  the  calculated  unfed  birds  were s t u d i e d f a c t o r , the  r e l a t i v e h u m i d i t y was  not  on mean  signifi-  d i f f e r e n t f r o m t h o s e o f o t h e r e x p e r i m e n t a l days  (Table  42  V)/....  The d i f f e r e n c e  a difference  r a t e must be r e l a t e d t o  i n t r e a t m e n t o r be an a r t i f a c t  number o f t r i a l s . r e a s o n s why  i n evaporative  T h e r e a r e a t l e a s t two h i g h l y  unfed b i r d s  water l o s s .  due t o t h e s m a l l  might have lower r a t e s  I t i s possible  dehydrated than the others  that  speculative  of  evaporative  t h e u n f e d b i r d s were more  as t h e y were p r e v e n t e d  access to  water a f t e r r e c e i v i n g t h e i r s a l t  l o a d whereas t h e o t h e r 2  g r o u p s were a l l o w e d  d r i n k i n g water a v a i l a b l e .  The  4 hours with  g u l l s were o b s e r v e d t o d r i n k  that  these  that  the unfed b i r d s  birds  fluid  This  birds  chloride portion  given  concentration  received  fish  i n these b i r d s ' s a l t The b i r d s  than the f e d  a ratio  of NaiCl  p o t a s s i u m was included  salt  significantly  load  load  g r o u p was  fish  fish  o f 1-1 and t h e b i r d s o f 0:39.  gulls. of  compared t o t h e f e d  t h a t were f e d o n l y  received  and  given  salt only  The d i s c r e p a n c y  associated  a  came  with both  sodium  c h l o r i d e w h e r e a s t h e a n i o n component o f t h e  phosphate, bicarbonate  compounds.  higher i n  i n the unfed  o f 1:2, t h o s e t h a t were g i v e n  l o a d h a d an N a : C l r a t i o  organic and  rate  by t h e l a r g e r p r o p o r t i o n  about because the e n t i r e anion and  was  o f the c l o a c a l e x c r e t i o n  ( T a b l e 113) .  Na:Cl r a t i o  salt  A second p o s s i b i l i t y i s  have a l o w e r m e t a b o l i c  c a n be r e a d i l y e x p l a i n e d  chloride  an  d i d so.  so i t i s l i k e l y  and t h u s a l o w e r r e s p i r a t o r y w a t e r l o s s . The  the  fish-fed birds  after eating  and a l a r g e  The a d d i t i o n a l s a l t comprised of NaCl.  load  variety of  given  to the f i s h  43 Unfortunately, study  does n o t  is  important  an  due  really  test  route  the h y p o t h e s i s  f o r s o d i u m and  der normal c o n d i t i o n s . were n o t  to the experimental  The  reason  g i v e n water d u r i n g the  therefore, excretion  the experiments and  salt  ing dehydration. pertains  absence o f d r i n k i n g water. lost  due  t o e v a p o r a t i o n d u r i n g the  40 ml  of  free water  2 4 hour c o l l e c t i o n  t o 336  The  in this 24  compared w i t h  study  cannot  h o u r w a t e r and those  mosm/1). be  Thus, the e x t e n t  of  from  s u b j e c t e d t o a 33 h o u r c o l l e c t i o n  of s a l t  cal  e x c r e t i o n without  1972)  Since Stewart  r e p o r t e d o n l y d a t a on b i r d s  "measurable" s e c r e t i o n , present salt and  study  gland i s higher lower  Stewart's in  are used  the  for K  +  d a t a on  the  +  (2% v s . 9.5%  distribution  57%  o f the  total  difference the p r e s e n t  o f sodium output  i n methodology study  s i n c e the  included f l u i d  and  f o r 24  (Table  that  hours  VIII).  The  i s probably  solid  +  the  from  total  excreted)  c l o a c a l Na  cloa-  produced  of the  study.  are  g l a n d and  Ion o u t p u t  (75% v s .  as compared t o t h e p r e s e n t  gulls  ' s e c r e t o r s ' from  f o r comparison.  f o r NA  trivial.  the  and  (Stewart,  period by  considered  i o n output  was  fluids  o f d u c k s t h a t were f a s t e d  water  cloacal  to s u r v i v e i n the  a b o u t 6%  dehydration  birds  q u e s t i o n as i t  t h e o s m o l a l i t y o f t h e body  300  un-  hours of i n c r e a s -  w h i c h s h o u l d have r a i s e d (e.g., from  gland  period,  t o measure  interesting  Nearly  salt  i s t h a t the  d u r i n g 24  o f marine b i r d s  this  elimination  hour c o l l e c t i o n  gland secretion  t o the a b i l i t y  chloride  were d e s i g n e d  T h i s i s a l s o an  t h a t the  for this  24  protocol,  the excreted)  in  discrepancy due  to a  output  cloacal Na  +  from whereas  44  TABLE V I I I .  C o m p a r i s o n o f 24 h o u r w a t e r and i o n o u t p u t i n G u l l s , L a r u s g l a u c e s c e n s , and Ducks, Anas platyrhynchos . a  H 0,  yl/lOOgBW  I o n e x c r e t i o n , y e q / l O O g BW Na K+ C l +  Gulls (secretors) n=6 salt  gland  -  b  359+ 71  133  +26  17+ 7  cloaca  1100+281  100  +35  159+25  evaporation  6912+978  162  +42  5+ 1  b  185+42  C  63+29  d  Ducks n=6 salt  gland  283+ 76  cloaca  2210+237  evaporation  6200+380  Data  converted from Table  54.5+14.3  2., S t e w a r t  S e c r e t o r s were d e f i n e d as t h o s e 1 ml o f f l u i d .  that  189+13  (19 7 2 ) . secreted at least  S t e w a r t measured o n l y salt  gland  fluid  Na  gulls  and  excreted greater  the  d u c k s do  similarly  cloacal  during  output  from the  dehydration.  v i a the  salt  than the  gland  gland  i s at  (Douglas  least v i a the  sodium i o n  (1972) and  this  e q u a l t o and cloaca  gland  s e c r e t i o n may  e x p e r i m e n t was  be  an  the  the  salt  f o r m e r two gland  diminishing secretion that  can  fluid  during  are  cloacal  be  i n the  modifications  and  solids  periods,  to other  T h u s , i t may  dehydration  hydrated conditions. collection  due  may  be  short  two  the  term  designed Stewart  i n re-  studies  indi-  contribution dehydration  contribution  that  salt  such  of as  gland  emergency measure  only.  protocol r o l e s of  used i n the  salt  i n f e d and  p r o v i s i o n of water  e l i m i n a t i o n of  to  Phillips,  constraints  be  i n ion excretion  These a r e :  the  a limited  to the  necessary to quantify  fluids  &  load.  important  indicate that  limited  volumes.  aid survival Several  study  may  studies  species.  compared  towards m a i n t a i n e n c e of osmotic homeostasis d u r i n g while  possibly  70-89% i n  Ensor  These l a t t e r  sodium  i n both  i n response to a s a l t  itself.  Thus,  excretion  e x p e r i m e n t e r measured s e c r e t i o n r a t e  sponse to d e h y d r a t i o n salt  cloacal  amount o f  1969;  the  the  gull  i s 73%.  decreases of  & Neely,  However, i n b o t h c a s e s ,  that  gland  s e c r e t i o n volume i n d e h y d r a t e d b i r d s  t o measure s e c r e t i o n r a t e s  cate  salt  Moreover, the  amount e x c r e t e d  hydrated controls 19 7 2 ) .  I n d e e d , when  i n terms o f  appear to d i s t r i b u t e  Other i n v e s t i g a t o r s r e p o r t salt  ions.  sodium output i s expressed only,  +  fluid  this gland, normally  during  t i m e between l o a d i n g  and  beginning  sample c o l l e c t i o n ,  secretion,  and s c a l i n g o f i o n l o a d i n g  y e t more c o m p l i c a t e d the  measurement o f t h e volume o f f l u i d  study  Crocker  a n d Holmes  A  i s n e c e s s a r y t o d i s t i n g u i s h among  s e v e r a l parameters t h a t d i r e c t l y  water e x c r e t i o n - - t h e  on a w e i g h t b a s i s .  d e t e r m i n e c l o a c a l i o n and  k i d n e y , t h e i n t e s t i n e and t h e c l o a c a (1971), P e a k e r e t al.,  itself.  (1968) and Skadhauge  .(1967, 1 9 7 6 ) , have d e m o n s t r a t e d t h e i m p o r t a n c e o f t h e i n t e s t i n e and  cloaca t o avian  salt  and w a t e r b a l a n c e ,  but the a c t u a l  t r i b u t i o n s o f t h e s e organs f o r f e d and h y d r a t e d not  con-  marine b i r d s has  been q u a n t i f i e d . A  final  question  r a i s e d by t h i s  s t u d y and  observations  by  McNabb e t a l . , (1973) i s w h e t h e r t h e r o l e o f t h e c l o a c a l s o l i d s  in  i o n e x c r e t i o n may be m o d i f i e d  i n response t o s a l t  McNabb e t a l . , (1973) f o u n d t h a t r o o s t e r s u t i l i z a t i o n when g i v e n  a salt  d e p e n d e n c e between s a l t handling this the  observation  urine  C.  some  protein  inter-  and d i e t .  I t w o u l d be i n t e r e s t i n g t o p u r s u e  by i n v e s t i g a t i n g whether marine b i r d s can v a r y i n r e s p o n s e t o t h e needs f o r i o n e x c r e -  F o r example, a change i n pH o r t h e ammonium c o n t e n t could  uric  change t h e p r e c i p i t a t i o n a n d b i n d i n g  of the  properties of  acid.  Conclusions The  to  load, which suggests  their  and p r o t e i n m e t a b o l i s m and t h u s t h e  amount o f bound i o n s  tion.  the  of s a l t  increased  loading.  r e s u l t s o f t h e s e two e x p e r i m e n t a l  several conclusions  regarding  salt  procedures  point  and w a t e r m e t a b o l i s m o f  Glaucous-winged G u l l s .  T h e s e b i r d s have r e l a t i v e l y  body w a t e r v o l u m e s , b u t  neither  TBW  turnover  change when t h e  the  TBW  volume n o r  g u l l s are  switched  high the  total  rate  from a  of  fresh-  water to a seawater d r i n k i n g regime.  Thus, t h e s e b i r d s  are  adapted t o v a r i a t i o n s i n the  of  water.  In c o n t r a s t , equivalent during that  the  t o w a t e r l o s s and  period.  rates with increased  adapted to t h e i r The  ions  and  salt  gland  secreted  about  the  birds  study.  in this  10%  of  response to a s a l t  l o a d by  gland  does p l a y  important  birds  i n f e d but  dehydration, birds  total  other  to  the  gland  as  a route  wastes w i t h o u t c o n t r i b u t i n g t o the  ion  fully  specifically  Since  f e d and for ion  excretion  for  in salt  these  ability  of  increasing  normally  hydrated  excretion.  a role i n ion removing  by  Thus, the  the  salt.  sodium  ion excretion  excretion  nitrogenous  osmotic pressure  p r e c i p i t a t e d w i t h the  to  total  role i n ion excretion  c l o a c a l solids also play  Cations  the  TBW  excessive  f u n c t i o n appears to decrease with  salt  mechanisms  able  marine s p e c i e s .  that normally  balance  potassium excreted  for extrarenal  a d d i t i o n t o t h e i r well-known r o l e of  urine.  not  d i s t r i b u t i o n of  dehydrated c o n d i t i o n s .  i t is likely  a l s o use The  an  the  rate  v o l u m e s and  g u l l s are  about h a l f of  This  s i m i l a r to those observed  gland  the  e n v i r o n m e n t o f a b u n d a n t w a t e r and  c h l o r i d e , and  salt  Thus, the  at a  water  Therefore,  i o n uptake, are  of water.  and  in  remain i n s a l t  drinking  t h e s e b i r d s have t o m a i n t a i n n o r m a l f l u i d  compensate f o r a l a c k  the  their  g u l l s were u n a b l e t o e x c r e t e  a 2 4 hour d e h y d r a t i o n  turnover  is  salinity  well  of  the  c l o a c a l s o l i d s ranged  48 roughly  from a f o u r t h to a h a l f of the t o t a l output o f  sodium and potassium.  T h i s important but o f t e n  f r a c t i o n should be i n c l u d e d i n any uricotelic The  s a l t balance s t u d i e s f o r  species. e f f e c t of f e e d i n g on the p a t t e r n s of s a l t  water e x c r e t i o n i s s t i l l effect.  neglected  ambiguous but  No d e f i n i t e c o n c l u s i o n s may  and  i t c l e a r l y has some  be drawn from t h i s  but 2 p o s s i b l e areas f o r s p e c i f i c r e s e a r c h are  study  identified;  1) c h a r a c t e r i z a t i o n of u r i c a c i d / i o n a s s o c i a t i n g c o l l o i d excretion patterns the d i e t , and, and metabolic The  i n terms of f e e d i n g and  2) comparison of e v a p o r a t i v e r a t e s between fed and  water l o s s r a t e s  be drawn from  d i s c u s s i o n i s t h a t although the  gland i s the primary a d a p t a t i o n of s e v e r a l c o o r d i n a t e d  salt  f o r s a l t e x c r e t i o n , i t i s only  adaptations  metabolism of marine a v i a n s p e c i e s .  i n the water and  and  q u a n t i f i e d i n order to f u l l y  the osmoregulatory processes  salt  Other, more s u b t l e , as-  pects of s a l t and water metabolism have been suggested need to be e x p l o r e d  of  starved b i r d s .  o v e r - r i d i n g c o n c l u s i o n t h a t may  these experiments and  one  p r o t e i n content  i n these b i r d s .  and  understand  49  V.  Two  SUMMARY  aspects o f osmoregulatory p h y s i o l o g y were c h a r a c -  t e r i z e d f o r Glaucous-winged G u l l s , a r e p r e s e n t a t i v e marine avian s p e c i e s , i n o r d e r to i d e n t i f y s p e c i f i c a d a p t a t i o n s to t h e i r marine environment and to d e s c r i b e the i n t e g r a t i o n o f s e v e r a l means o f i o n e x c r e t i o n i n fed b i r d s . Two  i n d i c e s o f o v e r a l l water metabolism, TBW  volume  and t u r n o v e r rate,were compared i n g u l l s adapted to d r i n k i n g f r e s h water and then to d r i n k i n g sea water t o determine i f o v e r a l l water metabolism was of sea water.  a f f e c t e d by prolonged i n g e s t i o n  These values were a l s o compared to those f o r  o t h e r a v i a n s p e c i e s by a l l o m e t r i c equations to see i f the g u l l s were unique w i t h r e s p e c t to these two parameters. Turnover r a t e , measured by THO  l o s s , was  no d i f f e r e n t i n sea  water adapted and f r e s h water adapted g u l l s , nor was  there a  d i f f e r e n c e between g u l l s and o t h e r b i r d s . The volume of TBW and there was  was  computed from i n i t i a l THO  no change w i t h d r i n k i n g regime.  s i z e o f the TBW  space was  space  However, the  u n u s u a l l y h i g h , e q u a l l i n g 79% o f  body weight compared to a mean o f 62% f o r o t h e r b i r d s . advantages a c c r u i n g from a l a r g e r r e l a t i v e TBW  Two  space may  be:  1) r e d u c i n g the change i n osmotic p r e s s u r e due to i n g e s t i o n o f h y p e r t o n i c s o l u t i o n s , and 2) a l l o w i n g a g r e a t e r degree of dess i c a t i o n b e f o r e t i s s u e s become i r r e p a r a b l y damaged due to dehydration.  50  A s e c o n d s e t o f e x p e r i m e n t s was d e s i g n e d the  excretion pattern  f o r s o d i u m , p o t a s s i u m and c h l o r i d e  when t h e s e a r e i n g e s t e d w i t h ponent the  f o r the g u l l s .  body  unlike  fluids  a fish,  o f the b i r d s  and c o n t a i n e d  i o n loads  were c o l l e c t e d f o r 24 h o u r s b e g i n n i n g  a nitrogen  gland  salt  This  gland  gland  i n roughly  equal  routes  ion loading.  ion collection  how t h i s  dissolved and  Unfortunately,  that  gland  i n the c l o a c a l f l u i d In t h i s  t o dehydrate  and i t i s n o t p o s s i b l e t o s t a t e i f o r function.  f r o m t h e c l o a c a were e x c r e t e d  mucous.  a c u t e and  t h e r e s u l t s a r e com-  t h e b i r d s were a l l o w e d  a f f e c t e d the s a l t  Ions  v i a the  a t t e s t s t o the f u n c t i o n a l importance o f the  p r o m i s e d by t h e f a c t during  feeding.  i n the s a l t  i n c i r c u m s t a n c e s w h i c h do n o t i n v o l v e  hypertonic  salt  and t h e c l o a c a  amounts w h e r e a s most o f t h e p o t a s s i u m was e x c r e t e d cloaca.  load  t o study  4 hours a f t e r  Sodium and c h l o r i d e , t h e d o m i n a n t i o n s v i a both  hyperosmotic t o  usually given  i o n e x c r e t i o n s from the s a l t  s e c r e t i o n , were e x c r e t e d  ions  a n o r m a l d i e t a r y com-  The f i s h was s l i g h t l y  the hyperosmotic  excretion,  to quantify  study,  i n two  forms—  o r bound t o t h e s o l i d  significant  portions  urates  o f the N a  +  + and  K  Na  and 61% o f c l o a c a l K  +  not a  excreted  detected  were m e a s u r e d i n b o t h +  i n the s o l i d  were i n t h e s o l i d portion but this  f u n c t i o n o f the a n a l y s i s Two b i r d s were g i v e n  eating a fish  f r a c t i o n s (43% o f c l o a c a l p o r t i o n ) ; CI a b s e n c e was  was  probably  used. the i o n load asssociated  but not the nitrogen  load.  This  with  d i d not affect  51 t h e p a r t i t i o n i n g o f i o n o u t p u t between t h e s a l t c l o a c a but d i d c o r r e l a t e in  the percentage  with  of cloacal  as o p p o s e d t o s o l i d  a decreased  ion output  EWL  found  gland and  and  increase  i n the  p o r t i o n of the c l o a c a l e x c r e t a .  fluid  52  REFERENCES 1.  A n d e r s o n , S. H. 19 70. Water b a l a n c e Junco. Auk 87:161-163.  o f t h e Oregon  2.  B a r t h o l o m e w , G. A. a n d T. J . Cade. 1963. economy o f l a n d b i r d s . Auk 80:504-539.  3.  Cade, T. J . and L . G r e e n w a l d . tion i n Falconiforme birds.  4.  Chapman, T. E . and A. L . B l a c k . 1967. W a t e r in chickens. P o u l t r . S c i . 46:761-765.  5.  Chapman, T. E . and L . Z. M c F a r l a n d . 19 71. Water t u r n over i n Cotunix Q u a i l with i n d i v i d u a l observations on B u r r o w i n g Owl, P e t z C o n u r e a n d V u l t u r i n e F i s h E a g l e . Comp. 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J . 196 8. W a t e r economy o f t h e S t a r k ' s L a r k and G r e y - b a c k e d F i n c h L a r k f r o m Namib d e s e r t o f S o u t h West A f r i c a . Compl B i o c h e m . P h y s i o l . 27:723-745.  56  APPENDIX COMPUTER  10  lOO  30 50  2 4  13  17 19 18  21  24  I  PROGRAM  CALL P I 1 3 0 IN=5 10=6 READ ( I N , l O ) NB FORMAT ( 1 3 ) N = N13*9 DO 5 J = l , NB WRITE ( 1 0 , 100) J FORMAT ( 1 H 1 , 12X, ' B I R D # ' , 1 3 . / / 1 2 X , ' T I M E ' . 10X. ' B ' , 8 X . ' D P M ' , S X , 1 ' M C I / M L ' , 4X-, ' T R U E M C I / M L ' , 6 X , ' L O G M C I / M L ' / / ) C A L L S C A L F (0. 5, 1. 0. O. , - 6 . ) C A L L FGRID ( 0 , 0, - 6 . . 1. , 14) C A L L FORID ( 1 . 0, - 6 . • 1. . 5 ) DO 2 5 I X = 1 , 2 SY = 0. S T = 0. S T Y = 0. S T S = 0. C = 0 X = 1. DO 15 I — 1 , 9 READ ( I N , 3 0 ) XT FORMAT (F5. 2 ) READ ( I N , 5 0 ) B FORMAT ( F 7 . 0 ) EF = . 256 DPM = B / E F XC = DPM/2. 2 E 3 I F ( 1 - 2 ) 13, 17. 19 T=XT BG=XC GO TO 13 BT-XT T = ( (X-2. )*43 (BT-XT))/24. CONTINUE XM = X C - B G I F (XM) ' 2 1 , 2 1 , 24 Y=l. C=C+1. GO TO 2 3 Y = ALOGIO(XM) NY =Y I F ( N Y - 1 ) 4 1 , 4 2 , 41  57  42 41  33 28 200 IS  201 202 61 300 25 5  C = C + 1. GO TO 2 3 SY = SY + Y S T Y = S T Y + T#Y ST = ST + T STS = STS + T * T CALL FPLOT ( - 2 , T. C A L L POINT ( I X - 1 ) C A L L PENUP WRITE ( 1 0 . 2 0 0 ) T» FORMAT ( I U . F 5 . 2, X=X+1.  Y) B, DPM, X C , XM, Y F 1 2 . 0, F l l . 0. E 1 4 . 3 ,  E14. 3.  F12. 5 )  CONTINUE XK = < S T Y - S Y * S T / ( 9 . - C ) ) / ( S T S - S T * S T / ( 9 . - C ) ) A = < S Y - X K * S T ) / ( 9 . •- C ) Y14 = X K * 1 4 . + A T5 = - . 693/XK I F <A . OT. O. . OR. A . L T . - 6 . . OR. Y 1 4 . GT. O. ) GO TO 61 C A L L F P L O T ( 0 , 0. ," A) I F <Y14 . L T . - 6 . ) iGO TO 201 X=14. Y=Y14 GO TO 2 0 2 Y=-6. X=<A+6. ) / X K C A L L FPLOT ( 2 , X. Y) C A L L F P L O T ( 1, 20. . - 6 . ) WRITE ( 1 0 , 3 0 0 ) XK, T 5 F6. 3, / / / / / / ) F 6 . 3. / 1 2 X , ' T ( 1 / 2 ) = ' FORMAT ( / / 12X, ' K = I F <J . EO. 5 ) GO TO 5 CONTINUE CONTINUE STOP END  •  58  APPENDIX I I DATA FROM INDIVIDUAL BIRDS FOR ION AND FLUID EXCRETION DURING A 24 HOUR COLLECTION PERIOD.  Table  1.  I o n l o a d , r e n a l and e x t r a r e n a l i o n e x c r e t i o n f o r i n d i v i d u a l b i r d s d u r i n g a 24 h o u r c o l l e c tion period.  Table  2.  W e i g h t l o s s e s and c a l c u l a t e d e v a p o r a t i v e w a t e r l o s s f o r i n d i v i d u a l Glaucous-winged G u l l s d u r i n g 24 h o u r s .  Table  3.  C o n c e n t r a t i o n s o f i o n s i n c l o a c a l f l u i d s and amount o f i o n p e r u n i t w e i g h t o f c l o a c a l s o l i d s f o r i n d i v i d u a l g u l l s d u r i n g 24 h o u r c o l l e c t i o n period.  TABLE 1.  Ion load, renal and extrarenal ion excretion for individual birds during a 24 hour collection period.  SALT CAPSULE FISH • SALT CAPSULE 8  9.  10  • DIST. HjO 11  12  13  INPUT g fish Na (ueq) K+_(Ueq) C l ~ (ueq) +  64 3232 4922 2739  70.5 3560 5422 3017  42.2 2131 3245 1806  63.2 3192 4860 2705  107.2 5414 8244 4588  35.5 1793 2730 1519  45.5 2298 3499 1947  62 10591 4768 10114  65 11133 499? 10032  69 10805 5306 10273  61 10431 4691 9961  3200 5000 8200  3200 . 5000 8200  OUTPUT SALT GLAND Na (ueq) K* (ueq) CI" (Ueq) +  CLOACAL FLUID Ueq)  Na*  K (ueq) CI" (ueq) CLOACAL SOLIDS Na+  (v, q) (ueq) c  total ueq K*  (ueq) (ueq)  total ueq CI"  38 4.0 2S  1683 395 2050  1613 159 2250  8 35 63 875  36 1.0 25  278 24 338  48 2.0  1300 105  494 50  683 70 1050  92 8 475  463 25 1050  913 116 500  83 413 93  276 410 290  272 237 89  456 861 •410  95 367 51  701 817 739  104 127 114  349 693 309  2363 1320 1709  21 139  332 235  596 770 1322  141 1018 1780  435 97 532  50 39 89  235 122 357  260 104 364  200 26 226  270 165 435  185 81 266  55 100 155  225 299 S24  355 16 371  . 50 121 171  135 5 140  70 26 96  740 150 890  315 93 413  875 401 1276  310 194 504  565 161 726  870 464 1334  140 364 504  360 341 701  475 650 1125  415 16 431  245 97 342  400 4 404  360 35 395  No or trace amounts of chloride were found i n a l l cloacal solids' samples.  TOTAL CLOACAL Na (ueq) 615 365 629 820 321 K* (ueq) 1303 823 1513 1365 1093 C l ~ Totals are as l i s t e d under cloacal f l u i d . +  TOTAL OUTPUT Na (ueq) K (ueq) CI* (ueq) +  +  653 1307 118  2053 1218 2340  2242 1672 2339  1655 1428 1285  357 1094 76  1136 2151  370 631  504 1394  2588 2445  392 570  503 577  736 1174  237 1413  1414 2175 761  418 633  1804 1499  3082 2495  1075 640  595 585  1199 1199 2372  1150 1529 2280  TABLE 2.  Weight losses and calculated evaporative water loss for individual Glaucous-winged Gulls during 24 hours.  •1  2  3  4  5  6  7  8  9  10  11  12  13  Body weight w  (g)  760  832  843  764  850  870  914  770  965  936  790  839  756  w  (g)  708  745  790  704  797  813  870  683  890  874  744  803  733  W  (g)  52  87  47  60  S3  57  44  87  75  62  46  36  23  4.47  4.58  2.06  0.75  0.74  0.13  3.47  1.32  1.99  .638  1.74  1.76  6.6  9.2  4.9  9.2  5.1  6.2  5.0  8.9  8.64  8.28  2.72  1.16  2.06  1.12  1.84  2.06  1.32  1.24  .40  .49  .047  .055  t  f  Salt aland ml H 0  a  2  Cloacal  .078  fluid  g  22.1  2.6  6.7  1.80  1.29  Cloacal solids g  1.09  g solids g fluids  .412  .126  .420  .122  .361  .332  .36 3  .139  .049  .192  .690  E v a p . 820° g  42.4  72.5  35.0  47.6  45.3  48.0  37.6  73.4  50.5  55.6  37.3  25.2  12.5  'Calculated using measured ion output and assuming ion concentrations equal to those measured for spontaneous secretion (Hughes, 1971a). 'calculated by assuming that a l l unaccounted for weight loss was due to evaporative water loss. CTl O  TABLE 3. Concentrations of ions i n cloacal fluids and amount of ion per unit weight of cloacal solids for individual gulls during 24 hour collection period.  2  1  Cloacal  3  4  5  7  6  8  10  9  11  12  13  17.0  fluid  N a roeq/1  12.,5  30.0  55.0  49.5  18.5  112. 5 21.0  39.0  106.5  8.0  49.5  69.0  K neq/1  62..5  44. 5  48.0  93.5  71.5  131. 0  77.5  59.5  54.5  35.0  89.0  +  +  Cl"  meq/1  14..0  Cloacal Na  +  Na/K  675  44.5  18.0  10.0  .530  1.14  118. 5 23.0  .254  850  34.5 .505  .825  77.0 1.69  153  ~  —  .142  1.41  123.0 215 .138  .775  solids  yeq/1  K ueq/1 +  31. 5  .200  Na/K  25.S  76. 7  196 328  356 .598  215  174  324  123  211  146  125  479  207  133  347  196  620  449  394  648  277  567  1029  240  265  1002  804  .280  .722  .311  326  .527  .221  .466  .861  .500  .347  .243  62  APPENDIX I I I EFFECTS OF TBW VOLUME ON THE ESTIMATED OSMOTIC EFFECTS OF A HYPERTONIC SALT LOAD.  Table  1.  E s t i m a t e d change i n o s m o l a l i t y f l u i d s o f a g u l l due t o a s a l t TBW v o l u m e s .  o f t h e body l o a d f o r two  63 It  i s observed  that  volume o f 80-88% W ( T a b l e species  i s 62% W.  volume p l a y hypertonic  G l a u c o u s - w i n g e d G u l l s have a TBW  I I ) w h e r e a s mean TBW volume f o r o t h e r  Could t h i s  apparently  l a r g e r TBW  a r o l e i n b u f f e r i n g the osmotic e f f e c t s o f a load,  s u c h as t h e i n g e s t i o n o f s e a w a t e r ?  answer c a n be p r o v i d e d  An  by t h e f o l l o w i n g t h o u g h t  experiment.  Assume 50 ml o f s e a w a t e r 1000 mosm/1 a r e g i v e n  t o an 800 g  g u l l with  I f the sea  body  fluid  water o s m o t i c a l l y  is  i s 62% W?  i n body  84% W?  fluid  t h e e n t i r e TBW volume, osmolality  increase  using  space  i n body f l u i d  Ruch a n d Hughes'  volume. Table  fluid  I.  i f t h e TBW  I f t h e time course o f s e c r e t i o n  such t h a t the s e a water o s m o t i c a l l y  extracellular the  o f 300 mosm/1.  e q u i l i b r a t e s with  what i s t h e i n c r e a s e volume  osmolality  (ECF) o n l y ,  e q u i l i b r a t e s with the the c a l c u l a t i o n of  osmolality  can s t i l l  (1975) e s t i m a t e  be done  o f ECF as 44% TBW  The r e s u l t s o f s u c h c a l c u l a t i o n s a r e p r e s e n t e d i n The o s m o l a l i t y o f t h e body  both values  fluid  o f TBW volume b u t t h e b i r d w i t h  volume e x p e r i e n c e s  16-29 mosm/1 l e s s  increases f o r t h e l a r g e r TBW  increase.  TABLE 1.  E s t i m a t e d change i n t h e o s m o l a l i t y o f t h e body f l u i d s o f a g u l l due t o a s a l t l o a d f o r two TBW v o l u m e s .  Change i n o s m o l a l i t y o f t h e body f l u i d s A mosm. Load e q u i l i b r a t e d with:  TBW wolume, % W 62% 84%  TBW  +64  +48  ECF  +130  +101  initial  plasma o s m o l a l i t y  = 300 mosm/1  l o a d = 50 m l o f 1000 mosm/1 s e a w a t e r W = 800 g  

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