Age- and sex- specific survival rates are essential for understanding population dynamics and discerning environmental influences on population parameters. Gunnison’s prairie dog (Cynomys gunnisoni, GPDs) is a colonial ground-dwelling squirrel inhabiting the sagebrush ecosystem of western USA. Despite their important role as a keystone species, little is known about the population ecology of GPDs. Our goal was to provide estimates of survival rates for a GPD population at Petrified Forest National Park, Arizona USA, and to discern factors influencing those rates. We applied the Cormack-Jolly-Seber (CJS) modelling approach to capture mark-recapture data collected from 1989 - 1995. We used an information-theoretic approach using the Akaike’s information criterion for statistical inference regarding the influence of age, sex and time on survival and detection probabilities.
Results/Conclusions
During this study, we followed the fate of 1756 prairie dogs that were marked and released as juveniles. Capture probability (p) differed between sexes, with a higher (0.979± 0.012) probability for females than males (0.841± 0.040); we detected no evidence for age or time-specific variation in this parameter. Mean age-specific survival for juveniles, yearlings, and adults was 0.461 (± SE = 0.019), 0.288± 0.022, and 0.482 ± 0.055, respectively; there was some evidence of sex difference in survival with females having higher apparent survival than males. Two CJS models, both of which included an interactive effect of age and time, accounted for 0.93 of total model weight, suggesting a substantial temporal variation in age-specific GPD survival rates. Our findings also suggest that yearling survival may be particularly sensitive to climate variation and thus warrants our further investigation. We will discuss the influence of population density and climatic factors on age-specific survival of Gunnison’s prairie dogs.