JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. British Ecological Society is collaborating with JSTOR to digitize, preserve and extend access to Journal of Animal Ecology. Summary 1. From two enclosed populations monitored for 13 and 11 years, timeand agespecific survival rates of roe deer were estimated in relation to age and study site by recent capture-mark-recapture methods. 2. The two populations were very different. Roe deer in Trois Fontaines, a 1360 ha reserve in east France, faced severe winters. The size of this highly productive population was roughly constant during the study period. Conversely, in Chize, a 2660 ha reserve in west France with mild winters, roe deer showed density dependence in reproduction and body weight. 3. As a general rule, females survived better than males, the survival rates of prime-age adults were the highest, and survival decreased after 7 years of age. Only the severe winters affected markedly the survivorship of roe deer. 4. In Chize only, juveniles survived markedly less well than prime-age adults. Since physical maturity was reached later in Chize than in Trois Fontaines, the length of the critical stage for survival may be sensitive to population dynamics. Therefore, as in other ungulates, the survival of juvenile roe deer appears to be very sensitive to external influences. 5. Despite marked differences between the two populations studied, the survival rates of prime-age adults were similar in Trois Fontaines and Chize. Thus, the survival of prime-age adult roe deer appears to be relatively insensitive to external influences. 6. The difference in survival between sexes for prime-age adults was close to values observed in dimorphic and polygynous ungulates. However, roe deer only exhibit a marginal sexual dimorphism in size, a small breeding group size and no sex differences in fawn mortality. Therefore, costs of sexual selection cannot account for this gender effect in roe deer, and changes in social interactions between females in these high-density populations could be involved. 7. The decline of survival after 7 years of age was probably related to tooth wear.
