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The ecology and population dynamics of blue grouse in the sub-alpine King, D. G.

Abstract

This study was designed to follow up previous studies (Bendell and Elliott 1967, Lance 1967, Zwickel and Bendell 1967) which suggested blue grouse regulated their numbers through juvenile mortality over winter, and to examine the population of grouse that lived their entire lives on winter range. Grouse were observed and collected in the sub-alpine of Vancouver Island between May, 1965, and June, 1966. Data from the uplands were compared to grouse on lowland breeding ranges. The major findings were: (1) A low density and apparently stable breeding population lived in the sub-alpine with sex and age ratios and recruitment similar to those of lowland populations. (2) All events of reproduction following spring migration were delayed approximately one month compared to the lowlands. Further, the nesting season was shorter by approximately four weeks. (3) Grouse in the sub-alpine selected open forest and hilly areas as on the lowlands. (4) In winter, some males at least, lived separately from hens and chicks. The males lived in the open forest of the upper elevations of the sub-alpine but the habitat used by the hens and chicks is unknown. (5) The main source of juvenile mortality, and hence population regulation, probably occurred in autumn with first snow fall and/or brood break-up. Late winter behavioral interaction may also be important in regulating numbers. (6) No factor of the sub-alpine was found that could explain the size and success of lowland populations. There was some evidence to suggest that the quality of food in the sub-alpine may.be important to reproductive success on the lowlands.

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