Breeding of the lappet‐faced and white‐headed vultures (Torgos tracheliotus Forster and Trigonoceps occipitalis Burchell) on the Serengeti Plains, Tanzania

Abstract

SummaryThe lappet‐faced and white‐headed vulture nests in a 1636 km2 study area on the Serengeti Plains were kept under observation from June 1972 to August 1973. Active nests were inspected from a light aircraft at intervals of approximately 2 weeks.The inverse nesting densities were estimated as 43 km2/pair for the lappet‐faced vulture and 409 km2/pair for the white‐headed vulture. Nests were built of sticks in exposed sites on the crowns of trees, Acacia tortilis being the most popular species. Where the previous history was known, 44% of lappet‐faced vulture nests were newly constructed, and the rest re‐used from the previous year.The incubation period was about 55 days and the fledging period about 100 days in both species. Juveniles continued to frequent their nests after they could fly, sometimes for several months.Most lappet‐faced vultures laid their eggs in April‐May, the white‐headed vultures in June‐August. This means that the lappet‐faced vultures raised their young during the dry season, when Grant's and Thomson's gazelles were the only animals present in any numbers on the plains. By contrast, the Ruppell's griffons nesting in the nearby Gol Escarpment colony raise their young during February‐May, when the wildebeest and zebra herds are normally on the plains.The survival rate of lappet‐faced vultures from laying to fledging was about 40%. The chicks are thought to be vulnerable to predation by tawny eagles, and one was known to have been killed by a leopard. Three adult vultures were killed on their nests, from unknown causes.Food remains from lappet‐faced vulture nests showed a heavy preponderance of Grant's and Thomson's gazelles in all cases, with golden jackal the next most commonly occurring species. No food remains were obtained from white‐headed vulture nests.The possibility of using aerial counts of vulture nests as an indicator of productivity is discussed.