OBSERVATIONS ON THE BREEDING OF THE PINK‐BACKED PELICAN PELECANUS RUFESCENS

Abstract

SummaryThis paper summarises observations on the breeding behaviour of the Pink‐backed Pelican Pelecanus rufescens at Rakewa, Nyanza Province, Kenya, where the species has bred for at least 200 years. Observations covered most of one breeding season, November 1962 to April 1963.Of at least 250 nests, 35 were closely observed. The community consisted of about 815 pelicans of which about 540 were adults. The death rate is estimated at 13% per annum and the mean life‐span at about seven and a half years.The breeding site, in trees above a small swamp, is 15 miles from the favoured feeding ground. The colony is protected by local Luo people.The pelicans feed and roost mainly at the Miriu Delta, 15 miles away, travelling between the two places so high up as to be unseen. They fish in the early morning, visiting the colony to feed young mainly between 09.00 and 13.00 hrs. Once the young are large both parents roost away from the colony at the Delta.The breeding season takes place from August, towards the end of the rains, to March, at the end of the dry season. The birds breed in synchronised groups, the breeding cycle for any group occupying five months.Nuptial display is performed on the nest trees, by single pairs or small groups. Two main displays are described, “pointing” and “bill‐clapping”. Mating occurs on the nest, with little preliminary display.Nests are slight stick structures, repaired from year to year, and used by other pelicans if abandoned. The clutch is normally two eggs, occasionally three. Both sexes incubate, with infrequent change‐overs, for 33–35 days.The chick is first brick‐red, becoming covered with white down. Feathers break through at about 12 days and have covered much of the body by 30 days. At 40 days chicks can recognise their own parent. They fly at 70–75 days.Parents feed chicks by regurgitation, sometimes into the nest. They brood them closely at first, but after 10–12 days leave them much alone. Large chicks thrust the head far into the parental gullet, and injuries result from such feeding struggles. Feeding usually occurs before mid‐day, each parent normally delivering two feeds with a rest between. Curious convulsive movements of the young are probably begging displays.Forty‐two young hatched in 35 nests, an average of 0.6 chicks/egg laid. The heaviest mortality among young occurred between 10–30 days when 31% of all chicks died. Young which flew were produced at the rate of 0.47/egg hatched, 0.28/egg laid, and 0.57/pair.