The 1937 Census of Gannets on Ailsa Craig; with Notes on Their Diurnal Activity

Abstract

A census of gannets, Sula bassana, by direct counts and the alighting method, gave approximately 5945 nests, an increase of about 24% over the previous year. This increase occurred only in localized regions of the Craig, while some decrease occurred in other parts. Evidence is given of birds suffering from plumages soaked by ship oil wastes in the water. Diurnal activity, measured by the number of birds alighting, began at 5 a.m., increased irregularly until 1 p.m., then tended to decrease during the rest of the day, although there was some increase in activity evident at 6 p.m.