Factors limiting population growth of non-cyclic collared lemmings at low densities ...

• Main Author: Reid, Donald Grant
• Format: Text
• Language: English
• Published: University of British Columbia 2009
• Subjects: Northwest Territories
• Online Access: https://dx.doi.org/10.14288/1.0088414; https://doi.library.ubc.ca/10.14288/1.0088414

I examined factors limiting population growth of collared lemmings (Dicrostonyx kilangmiutak) at low densities (<3 adults/ha), at Pearce Point, Northwest Territories, Canada. Populations were followed by mark-recapture, and radiotelemetry. They fluctuated annually, typically with summer declines, and winter increases. I tested the hypothesis that predation mortality limits population growth in summer, by comparing a population in an 11 ha predator exclosure (PE) with three control populations (18-25 ha). Predation, principally by red fox (Vulpes vulpes) and rough-legged hawks (Buteo lagopus), was the proximate cause of most adult and neo natal mortality. No other mortality factor compensated for decreased predation mortality in PE. Adult survival and recruitment increased significantly in PE. Controls declined in 1990 and 1991. PE declined less quickly. It did not grow, because weanlings dispersed long distances (53 m/d), and frequently left PP. I conclude that predation mortality is sufficient and ...