Report Nr. 2904 Regional Environmental Differences and Their Effects on Fawn Productivity

Regional variation in white-tailed deer (Odocoileus virginianus) fawn productivity rates has been observed in many states. Michigan is no exception, with fawn productivity rates of 0.65 fetuses/doe in Region III and 0.07 for Region I. This study was initiated to investigate the effects of different photoperiods (ESD = early short day, LSD = Late Short Day) on the onset of puberty in white-tailed deer fawns. Differences in growth rates and body weights were recorded for the ESD and LSD treatments within 2 weeks after the decreased light (8L-16D) regime was initiated. During the period of 8 August - 15 October, when both light regimes were 16L-8D. weights of the paired fawns were not statistically different. During the period 16 October - 5 December, when the ESD group was on a 8L-16D regime, ESD weights were heavier. LSD weights were heavier during the period 6 December - 6 February when they were switched to the 8L-16D photoperiods. Examination of blood progesterone levels, and ovarian and uteral development indicated that 7 of 8 fawns in the ESD treatment had undergone estrus in late January-early February, while none of the 8 in the LSD treatment had sexually matured.