Interspecies Interactions between Axis (Axis axis) and Fallow (Dama dama) Deer at Supplemental Food Patches

Abstract

In Texas and elsewhere, the introduction o f exotic deer species and the creation of sympatric multispecies assemblages has increased. However, little information on interspecific behavioral interactions and contest competition exists. I observed the number of displacements between axis deer (Axis axis) and fallow deer (Dama dama) categorized by age (adult vs. yearling male), sex, and species at patches o f supplemental feed. Behaviors used in displacements in order o f estimated energy cost included direct approach (low cost), ritualized display, (mid-cost), and bodily contact (high cost). Characteristics o f the populations o f both species o f inter- and intraspecific herds at food patches were recorded in an attempt to correlate them with displacement patterns. Axis males performed fewer interspecific displacements than fallow males in autumn (G = 19.3, d.f. = 3,p = 0.0002) and winter (G = 25.03, d.f. = 3,p < 0.0001), while fallow males performed fewer interspecific displacements than axis males in summer (G = 24.83, d.f.= 3,p < 0.0001). Fallow females engaged in fewer displacements than axis females in the spring (x2 = 7.702, d.f. = l,p - 0.0055). The distribution o f behaviors used to perform displacements did not differ between conspecifics and heterospecifics for either species. Heterospecific displacements between axis and fallow males were correlated primarily with the proportion o f fallow males in hard antler at feed lines. Fallow female displacements were correlated primarily with season. I conclude that interspecific dominance interactions between these species are resolved by differences in antler morphology and aggressiveness.