BREEDING OF THE ADÉLIE PENGUIN PYGOSCELIS ADELIAE AT CAPE BIRD

• Published in: Ibis
• Main Author: Spurr, E. B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1975
• Subjects: Cape Bird; Ross Island; Antarc*; Antarctica; Pygoscelis adeliae; Sea ice
• Online Access: http://dx.doi.org/10.1111/j.1474-919x.1975.tb04220.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1474-919X.1975.tb04220.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1474-919X.1975.tb04220.x

Summary Observations were made during four seasons (1967–68, 1968–69, 1969–70, 1970–71) on the breeding of Adelie Penguins at Cape Bird, Ross Island, Antarctica. Breeding data from individuals were related to date of return, laying date, clutch‐size, nest location, and change of mate. Some females consistently laid near the mean date of laying, while others were consistently early or late layers. Laying date may be under direct genetic control, or may reflect feeding ability. The mean clutch‐size was smaller in peripheral compared to central nests, and smallest of all in isolated nests. Clutches laid late in the season were smaller than those laid near the peak date, and small, late clutches were laid in peripheral rather than central nests. These differences may reflect age and/or feeding ability. Penguins that are better able to find food will return earlier, obtain central sites, and have larger clutches than those with a lesser ability. The two main causes of egg and chick losses were predation and parental failure. Losses were highest in single‐egg clutches, at isolated and peripheral nests, and among eggs laid late in the season. These results may be partly related to the age and experience of the penguins. However, regardless of age, peripheral nesting and late laying were always disadvantageous. The sex ratio of adults in the colonies was 117♂:100♀. This may be explained by the higher mortality of females. Some males could not find partners, but females that did not breed had probably been unable to obtain sufficient food for gonad development. The return of penguins, incidence of non‐breeding, adult mortality, clutch‐size, and breeding success at Cape Bird were all markedly different in 1968–69 compared to the other three seasons studied. This season was marked by the persistence of sea‐ice along the northwestern shores of Ross Island. The low reproductive output in 1968–69 was thought to result from a shortage of food for egg‐laying and incubation.