Timing and synchrony of birth in a hider species, the roe deer Capreolus capreolus

Abstract

Timing of birth was determined for 292 roe deer (Capreolus capreolus) fawns belonging to 146 litters on an island in central Norway between 1991 and 1994, and for 33 fawns belonging to 19 litters from an inland site from 1995 to 1997. On the island site there was no significant variation between years in the mean date of birth, 22 May, nor was there any significant effect of dam age, fawn sex, or litter size. Individual does tended to give birth close to the same date in consecutive years. Mean birth date at the inland site was 5 June. The births showed a relatively high degree of synchrony with 80% occurring within 26 days and 24 days at the island and inland sites, respectively. Copulation dates were much more synchronized than birth dates on the island site. Gestation length averaged 301 days, although individuals varied by up to 26 days. When comparing published data from European populations, there appears to be extensive variation in timing of birth, while birth synchrony is very conservative. There appears to be little possible anti-predator benefit for roe deer in any pattern of birth synchrony. Because of their high post-natal investment and large litter size, we hypothesize that roe deer are constrained to give birth close to the peak of forage productivity.