Spatiotemporal Variation in Survival of Male Yellow-bellied Marmots

Abstract

Variation in vital demographic (e.g., survival) rates of males can influence population dynamics, but the male segment of the population is frequently ignored in ecological studies of mammals. Using a multistate capture–mark–recapture model and 44 years (1962–2006) of data from 17 habitat patches, we investigated spatial and temporal variation in age-specific survival rates of male yellow-bellied marmots (Marmota flaviventris) in Colorado. We hypothesized that apparent survival rate of juvenile males would show the greatest spatial and temporal variation as younger animals are more susceptible to extrinsic environmental factors, survival of yearling males would vary over space because of documented spatial variation in dispersal patterns, and survival of adults would be less variable than that of juveniles or yearlings and would vary over space because of demonstrated spatial variation in site quality. Our results revealed that, as predicted, the survival of juveniles varied over time and among sites, whereas that of yearlings varied among sites but not over time. The survival of adults did not vary significantly over time or among sites. We also examined the effects of several intrinsic and extrinsic environmental factors on spatial and temporal variation in survival rates. Our results suggest that male marmots of different ages respond differentially to temporal and spatial variation in environmental factors.