Data from: Reproductive success is energetically linked to foraging efficiency in Antarctic fur seals Jeanniard-du-Dot, Tiphaine; Trites, Andrew W.; Arnould, John P.Y.; Guinet, Christophe; Arnould, John P. Y.
The efficiency with which individuals extract energy from their environment defines their survival and reproductive success, and thus their selective contribution to the population. Individuals that forage more efficiently (i.e., when energy gained exceeds energy expended) are likely to be more successful at raising viable offspring than individuals that forage less efficiently. Our goal was to test this prediction in large long-lived mammals under free-ranging conditions. To do so, we equipped 20 lactating Antarctic fur seals (Arctocephalus gazella) breeding on the Kerguelen Island in the Southern Ocean with tags that recorded GPS locations, depth and tri-axial acceleration to determine at-sea behaviours and detailed time-activity budgets during their foraging trips. We also simultaneously measured energy spent at sea using the doubly-labeled water (DLW) method, and estimated the energy acquired while foraging from 1) type and energy content of prey species present in scat remains, and 2) numbers of prey capture attempts determined from head acceleration. Finally, we followed the growth of 36 pups from birth until weaning (of which 20 were the offspring of our 20 tracked mothers), and used the relative differences in body mass of pups at weaning as an index of first year survival and thus the reproductive success of their mothers. Our results show that females with greater foraging efficiencies produced relatively bigger pups at weaning. These mothers achieved greater foraging efficiency by extracting more energy per minute of diving rather than by reducing energy expenditure. This strategy also resulted in the females spending less time diving and less time overall at sea, which allowed them to deliver higher quality milk to their pups, or allowed their pups to suckle more frequently, or both. The linkage we demonstrate between reproductive success and the quality of individuals as foragers provides an individual-based quantitative framework to investigate how changes in the availability and accessibility of prey can affect fitness of animals.; Usage notes
AFS females dataData collected on Antarctic fur seal colony on Kerguelen Island during the breeding season in 2012. Only females were selected. capt = capture date, massrecap = mass at recapture, lengthrecap = length at recapture, girthrecap = girth at recapture, departure= date of departure at sea, return = date of return to colony, minatsea = foraging trip duration in min, DEEkJd = Daily energy expenditure at sea in kJ/d, pup = ID of the female associated pup, Psex = sex of the pup associated with the tracked female, timeonland = time females spent on land between capture and departure at sea and between return and recapture, PCA = number of Prey Capture Attempts during foraging trip,Scat analyses dataScats were collected on the fur seal colony and were analysed for hard part remains. KFS1201 to KFS1214 indicate number of individual scats.AFSDietScats2012.xlsxAntarctic fur seal Pup dataMorphometric data collected on Antarctic fur seal pups on Kerguelen island during the breeding period in 2012. Tag# = ID of individual pups, Date = date of morphometric measurements (first date is birth date), mass = mass in kg, length = length in cm, girth = axillary girth in cm, sex = sex of pup.Pup data T. Jeanniard du Dot.xlsxTelemetry data of female Antarctic fur seals at sea.Telemetry data was collected using MK10 tags from Wildlife Computers for one foraging trip of breeding Antarctic fur seal females on Kerguelen during the breeding season 2012. Females are identified with a individual number from 21 to 40. File named Locations provide the latitude and longitude of GPS points collected. File named Archive provide dive depth (in m) of females at sea as well as water temperature (in C) and light levels in water at sampling rate of 1Hz during the foraging trip.Telemetry data.zip
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