Aggressive behavior of white‐tailed deer at concentrated food sites as affected by population density

Abstract

ABSTRACTConcentrated food sources are used frequently in white‐tailed deer (Odocoileus virginianus) management and research, but because such food sources are easily defended, aggressive interactions among deer may influence their effectiveness. The objectives of this study were to determine if deer population density or season affect 1) the order or degree of social dominance among different age and sex groups of white‐tailed deer, 2) the rate at which aggressive interactions occur, 3) the severity of interactions, and 4) the extent to which subordinate groups avoid dominant groups. We conducted our study in South Texas using 2 sets of 3, 81‐ha enclosures managed at varying deer population densities. We captured aggressive interactions using digital trail‐cameras placed at sites with spatially concentrated food. We found that bucks ≥2 years of age were dominant over all other age and sex groups in ≥87% of their interactions regardless of deer density or season. The odds of a buck dominating over a doe increased by 10% (95% CI = 0–21%) for each additional deer/km2 during summer, but density had little effect in any other season. Yearling bucks were dominant in 81% (95% CI = 51–100%) of their interactions with does during spring, whereas during other seasons we found no clear order to the dominance hierarchy. Social dominance between yearling bucks and does was not affected by population density. The rate of aggressive interactions increased by 2% (95% CI = 1–3%) for each additional deer/km2 and did not differ by season. Ten percent (95% CI = 6–14%) of interactions involved more violent behaviors that we characterized as severe; this percentage did not change with population density or season. At all population densities, during all seasons, does avoided bucks at sites with concentrated food; however, the degree of avoidance declined with increasing deer density in all seasons except spring. Our results indicate that as population density increases, so do social pressures that may limit access of subordinate age and sex groups to concentrated food sites. Therefore, concentrated food sites are not equally accessible to all age and sex groups of deer and the effectiveness of such sites in deer management and research may become increasingly limited as population density increases. © 2013 The Wildlife Society.