Chick loss in the Falkland Skua Catharacta skua antarctica

• Published in: Ibis
• Main Author: LAMEY, CAMELIA SYKES
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1995
• Subjects: Austral; Antarc*; Antarctica; Catharacta skua
• Online Access: http://dx.doi.org/10.1111/j.1474-919x.1995.tb03244.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1474-919X.1995.tb03244.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1474-919X.1995.tb03244.x

Data on reproductive success of 110 Falkland Skua Catharacta skua antarctica pairs were gathered during the austral summers of 1988–1989 and 1990–1991 on New Island, Falkland Islands. Adults laid two eggs 2–3 days apart and began incubation with the first egg. For the years combined, 1.39 chicks per nest hatched and 0.84 chicks per nest fledged (fledging was defined as surviving to 16 days of age). Brood reduction was common; 43% of the two‐chick broods were reduced to one, and mortality was concentrated on the younger chick. Although asynchronous hatching and differential death are consistent with Lack's brood reduction hypothesis, application of O'Connor's quantitative criterion revealed that sibling competition may not be responsible for the observed chick mortality. Furthermore, because no aggressive interactions between chicks were observed or detected indirectly, siblicide may be absent in this population. Instead, predation modified by a variety of factors may have led to the greater mortality of the second‐hatched chick.