THE BLACK NODDY ANOUS TENUIROSTRIS ON ASCENSION ISLAND PART 1. GENERAL BIOLOGY

• Published in: Ibis
• Main Author: Ashmole, N. P.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1962
• Subjects: Bird Island
• Online Access: http://dx.doi.org/10.1111/j.1474-919x.1962.tb07246.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1474-919X.1962.tb07246.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1474-919X.1962.tb07246.x

SUMMARY Several colonies of Black Noddies Anous tenuirostris on Boatswain Bird Island, off Ascension, were studied for almost a year, including the whole of one breeding period and the start of another. Between the breeding periods the noddies roosted on their ledges in the breeding colonies, so observations could be made throughout the year. The single eggs were laid on small ledges, usually on steep cliffs; nest material was scarce, and some eggs fell off the ledges during incubation, but many young were reared successfully in the first part of the breeding period. However, food shortage resulted in slow growth and eventual death of all the chicks hatched later in the season, and the weights of adults were also low at this time. It was shown that individual noddies sometimes bred at intervals of much less than a year, and that breeding occurs in different months in different years; however, the interval between the start of breeding in 1958 and 1959 was almost a year, and i, t is suggested that this was unusual, and a result of the food shortage late in 1958. The moult of the noddies was studied in detail; it was found that individuals were either involved in breeding activities, or were in process of moult, almost all the time, while a few birds started breeding well before they had finished their moult. The discussion concerns the reason for the rough synchrony in breeding among the Black Noddies on Ascension, and the relation between breeding and moult cycles in the population.