OVER-WINTER BODY MASS AND CONCEPTIONS OF WHITE-TAILED DEER IN CENTRAL TX

Abstract

At lower latitudes ungulate reproduction is often seasonal but the duration of mating and parturition seasons can be long. To further understand the adaptive significance of synchrony in reproductive events we examined two hypotheses to link over-winter body mass with lower synchrony of conceptions in a wild population of white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) in central Texas. If females maintain over-winter body mass then the window of time that conception occurs should be relaxed and longer relative to females where over-winter body mass declines. Across nine years we measured body mass in 1.5-year-old and older females in November (n = 170) and in March (118). In March we also measured forehead – rump lengths in offspring of gravid females and calculated conception dates. Over-winter body mass did not decline but was maintained, on average, across the years of study. Conception dates ranged over 50 days and 52% of conceptions occurred in a two-week period centered on the median conception date. Relative to northern populations of deer, there was lower synchrony in conception dates. White-tailed deer across the geographic range appear to be flexible in over-winter body mass dynamics that affects duration of reproductive events such as conception.