Midwest Fish & Wildlife Conference 2018

AUTHORS. Michael Joyce, University of Minnesota Duluth; John Erb, Pam Coy, Barry Sampson - Minnesota Department of Natural Resources; Ron Moen, University of Minnesota Duluth

ABSTRACT. Dispersal is a condition-dependent behavioral strategy with implications for gene flow, meta-population dynamics, and social structure. Many studies have focused on understanding the conditions that influence the strength and direction of density-dependence and sex-bias in animal dispersal. Although mating system and social structure are among the factors proposed to explain dispersal strategies, relatively few studies have tested for density-dependence or sex-bias in dispersal by solitary, territorial carnivores. Our objectives were to evaluate how age, sex, and population dynamics influence dispersal probability, distance, and timing in American martens, a solitary carnivore exhibiting intrasexual territoriality. We radiocollared 150 martens from 2008-2015 and used telemetry locations, annual marten abundance estimates, and annual prey indices to test whether dispersal was influenced by age, sex, population density, or per capita prey resource density. Juvenile martens dispersed more frequently and earlier than adults. Females were more likely to disperse than males, but there was no difference in dispersal distances or timing between sexes. Neither marten density nor per capita prey density influenced the probability that individual martens dispersed, but we captured more juveniles and a greater proportion of monitored martens dispersed in years with better recruitment. There was no relationship between dispersal distance and marten density or per capita prey density. However, the three longest dispersal distances observed occurred at the highest marten density. Martens tended to disperse during the two months following the short, intense harvest season, when there was a flux of vacant territories, or during late winter, when temperatures were warmer, snow was compacted, and energetic costs of thermoregulation and movement were lower. Our results provide evidence for the roles of social structure, harvest, and population dynamics on dispersal in martens. Our results also demonstrate the importance of considering both inter-annual variation in population and resource density when testing for density-dependence.