UBC Theses and Dissertations
Telemetry study of dispersion and breeding biology in blue grouse. Lance, Arthur Norman
A general property of animal populations is their failure to continue increasing in number indefinitely, even when the habitat may contain enough resources to support more animals than are present at the time. Certain populations of blue grouse have expressed this property by failing to increase when the habitat has undergone changes that have produced striking increases in past cases. Other populations have expressed it by arresting their increase before the resources of the habitat were exhausted. In blue grouse populations on Vancouver Island, adult mortality is constant and it is restricted recruitment that has held these populations stable in the periods they have been studied, even though sufficient young have been produced to support an increase. The hypothesis that the behavior of territorial adult males affects the local occurrence of recruits and other grouse in general on the summer range was tested by studying dispersion during the breeding period. Information on dispersion and social behavior were obtained from nine grouse fitted with miniature radio transmitters. Data from non-instrumented birds supplement this work. The principal finding is that there was no evidence of social interaction causing females and immature males to occur in special places, and that no interaction of a sort that could affect recruitment occurs between blue grouse on their summer range. It is alternatively suggested that such behavior occurs in winter. Other conclusions are that the onset of estrus induces hens to seek out and become localized near a mate, that several hens may seek out the same mate, and that no lasting pair-bonds are formed. Each type of reproductive activity in blue grouse has a distinctive movement pattern, and perhaps movement rate, associated with it. Excepting for hens In estrus who briefly seek out mates, and some yearling males who are prevented by adults from remaining on territories, movements and local occurrence within the breeding range are unaffected by social interaction with other grouse.
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