Population fluctuation and changes in the quality of rock ptarmigan in Alaska ...

• Main Author: Theberge, John B.
• Format: Text
• Language: English
• Published: University of British Columbia 2011
• Subjects: Lagopus mutus; rock ptarmigan; Alaska
• Online Access: https://dx.doi.org/10.14288/1.0101834; https://doi.library.ubc.ca/10.14288/1.0101834

This study attempts to explain changes in abundance of rock ptarmigan (Lagopus mutus) at Eagle Creek, Alaska. It includes an analysis of population data collected from 1960 to 1969, and a test of an hypothesis: that there were no differences in the quality (survival, growth, behaviour) of rock ptarmigan chicks between years that influenced spring densities. Spring densities fluctuated between 1960 and 1969, reaching peaks in 1962 and 1968. This was the result of an orderly and generally synchronous change in the loss of birds (primarily juveniles) in winter, accompanied by changes in the production of young. Both acted together in most years to either increase or decrease numbers. Each contributed approximately equally to changes in total annual loss. Changes in the production of young were primarily caused by parallel changes in both clutch sizes and nest failures. Population regulation by direct extrinsic control appeared unlikely. Other than weasel predation on nests, no environmental factor external to ...