Conditional daily and seasonal movement strategies of male Columbia black-tailed deer (Odocoileus hemionus columbianus)

Abstract

Animals move to maximize fitness via resource acquisition, predator avoidance, thermoregulation, or mate access. Variations in movement strategies among and within populations often reflect habitat- or demographic-specific variations in fitness trade-offs. To examine these conditional movement strategies, we modeled seasonal and diel movement patterns of radio-collared adult male Columbia black-tailed deer (Odocoileus hemionus columbianus (Richardson, 1829)) on a temperate, predator-free island. Linear 10 h displacement and home-range areas reached annual maxima during autumn and minima during late winter, corresponding with known dates for breeding season and lowest quality forage, respectively. For all males in all years, initiation of increased movements began during spring and again, abruptly, in late September, immediately prior to peak breeding season. Larger antlered males continued increased movements longer into December, suggesting increased breeding effort relative to smaller antlered males. Time of day predicted movements during all seasons; however, we observed no strong evidence of the crepuscular or nocturnal movement bias typically noted in deer, likely relating to the lack of predators in our study area. In this way, male black-tailed deer adopted conditional, seasonally specific movement strategies to balance fitness trade-offs in resource acquisition, thermoregulation, and mate access.