 Reference Base  Reproduction and population density: trade-offs for the c... |
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Rachlow, J.L.; Berger, J., 1998. Reproduction and population density: trade-offs for the conservation of rhinos in situ. Animal Conservation 1 (2): 101-106, figs. 1-3, table 1
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| Location: |
Africa - Southern Africa - Zimbabwe |
| Subject: |
Reproduction |
| Species: |
White Rhino |
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Intervals between births have ranged from 2 to 6 years for white rhinos in MNP. Mean intervals for females in the WGP were 2.9 ? 0.1 years (n = 6 females, 21 intervals) during the early period and 3.3 ? 0.2 years (n = 8 females, 19 intervals) during the late period. Only one female in the low-density population has given birth to more than three calves, with a mean of 2.25 years for 5 birth intervals. This value is lower than the mean intervals for all adult females (n = 8) during the same time period in the high-density population. The binomial probability of this result occurring by chance is 0.018, suggesting that the females in the low-density group experienced significantly shorter birth intervals than females in the high-density group. Although intervals between calves appear to increase at higher population densities, data from more individuals are required to provide a robust test of this relationship.
Discussion
Birth intervals in rhinos and other non-seasonal breeders vary considerably, and may be relatively plastic with respect to population density. African elephant females in high-density populations exhibit longer intervals between births than those in lower-density areas. In black rhinos, a contrast between Hluhluwe (high density) and Umfolozi (lower density) reserves revealed that the mean calving intervals were 2.7 and 2.3 years, respectively. A mean birth interval of 2.6 years was documented for white rhinos in Umfolozi Reserve, with a range of 1.8 to 3.5 years. Although the sample sizes are small, data from MNP suggest that rate of calving was inversely related to population density.
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