The significance of breeding synchrony in the wildebeest

• Published in: African Journal of Ecology
• Main Author: ESTES, RICHARD D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1976
• Subjects: muskox
• Online Access: http://dx.doi.org/10.1111/j.1365-2028.1976.tb00158.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-2028.1976.tb00158.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2028.1976.tb00158.x

Summary Unlike most ungulates, whose offspring remain concealed for some time after birth, the offspring of the wildebeest and other alcelaphine antelopes (except harte‐beest) accompany the mother from the very first hour. Most other ungulates that have follower‐young either protect them effectively through a maternal or group defence (e.g. cattle, muskox, equids, and rhinoceroses), or are able to flee to sanc‐tuaries (e.g. goats, sheep and goat‐antelopes). In the Alcelaphini, primary reliance is placed on flight and on concealment among conspecifics; there is no effective defence against predators and no sanctuary. The spotted hyena is the primary predator on wildebeest calves. Over 80% of all wildebeest calves are born within an annual 2–3 week calving peak. During three different calving seasons (1 963‐65) in Ngorongoro Crater, Tanzania, mortality in small, dispersed herds was found to be far higher than in large aggregations. The evidence suggested that this antelope's unusual reproductive strategy is adapted to the mobile‐aggregated distribution pattern characteristic of migratory populations, rather than to the sedentary‐dispersed pattern seen in resident populations. Further study on this specific question was undertaken during the 1973 calving season, with particular attention to reproductive success in small herds. Calf survival in small herds averaged just over 50% at the end of the 1973 birth peak, compared to 84% in aggregations. Daily sampling showed that calving peaked at different times in different parts of the Crater; this resulted in an extended season, although the peak in each population unit was of approximately equal duration. In some areas, calving was virtually finished before the peak began in the aggregations. Mortality ranged from very high among early calves to low in herds whose peak coincided with that of a nearby aggregation. The lack of synchrony between Ngorongoro subpopulations apparently reflects microclimatic differences, there being a pronounced rainfall and vegetation ...