The lifestyle and biology of the Hooded Vulture at Sokoto, northern Nigeria, 1970 to 1973.

Abstract

The Hooded Vulture was studied in and around Sokoto town, in north-west Nigeria, in the years end-1970 to mid-1973. We estimated that 1500-2000 Hooded Vultures lived at Sokoto, based on counts at the abattoir. We mainly followed the nesting of the species, and to that end located more than 320 nesting trees. Faidherbia (Acacia) albida was the tree most used; the average height of nests in eight species of tree was 8.1 m (sd ± 3.2), being highest in the Borassus Palm. Overall egg-laying dates for first-laid eggs were 16 October to 20 February (averaging 15 December); replacement eggs were laid on average on 17 February. The incubation period of 13 eggs averaged 51 days (range 50 to 54 days). Growth in weight of chicks rose to about 1500 g at 70 days and levelled off. The wing grew straight from day 30 to day 90 at 5.2 mm per day. It peaked at day 120 at 96% of the adult’s wing length. The fledging period of 10 chicks averaged 108 days (range 98 to 123 days). During observations there was always an adult (sometimes two) present at the nest, and the chick is fed mouth-to-mouth by regurgitation. Average breeding success (chicks reared from eggs laid) was low at 41%, indicating some impact of our interference. Adults were caught on their nests eight times, and measured. There was little interaction between people and the vultures, and the local people were generally very tolerant of them.