XII.—Numerical Data on African Birds' Behaviour at the Nest.—II. Psalidoprocne holomelæna massaica Neum., the Rough‐wing Bank‐Martin

Abstract

SummaryPsalidoprocne holomelæna makes a pad of beard lichen (Usnea) on a ledge or in a narrow natural hole at any depth up to about 2 feet. The numerical data are derived from 800 hours' observations at Amani divided between seven nests. There is no proof that both members of a pair share brooding or feeding duty.The incubation period is 19 days, the fledging 24–27.The extent to which the eggs were incubated varied from 31 to 66 per cent., apparently without relation to temperature. The frequency curves of duration of spells on eggs, and of intervals when the eggs were uncovered, contrast strikingly with those of Hirundo smithii. In Psalidoprocne both spells and intervals are much longer, most of them being between 8 and 20 minutes. Absences exceeding 30 minutes are rare, but 84 minutes has been recorded.For the first week after hatching the young are brooded as much as the eggs, but after that date the amount of brooding they get varies widely from nest to nest.During the last half of the fledging period the normal brood of two young receives 12 to 20 visits, presumably with food, per 200 minutes (only one‐fifth as many as a brood of two Hirundo smithii). A solitary Psalidoprocne, nestling got 80 per cent, as much attention as a pair.Nearly all the young leave the nest‐hole within three hours of sunrise. They fly in the absence of their parents, and efficiently from the first moment.