Influence of date and body mass at fledging on long-term survival of sooty terns sterna fuscata

The Sooty Tern Sterna fuscata is a pan-tropical seabird that nests typically on isolated oceanic islands. Sooty Terns nest always on the ground, generally amongst sparse herb vegetation and often in large dense colonies, sometimes numbering hundreds of thousands of pairs (Gochfeld & Burger 1996, Schreiber at al. 2002). In most colonies, laying is highly synchronised; e.g. on Bird Island, Seychelles, in 1973, 90% of eggs in a colony estimated at 395 000 pairs were laid in a nine-day period early in the laying season (Feare 1976) although the remaining eggs were laid over an approximate six-week period. In that study, time of laying appeared to be critical in terms of fledging success. Eggs laid during peak laying produced more chicks of fledging age, and chicks that were heavier at fledging and which fledged earlier, than chicks from later eggs. Despite being perhaps the world’s most numerous tropical seabird (Schreiber et al. 2002), few aspects of its life history have been quantified (Hamer et al. 2001). Here, I analyse data from birds ringed as chicks on Bird Island, Seychelles in 1972-1973 and recaptured during searches for ringed birds in 1994-2001, in order to examine the relationship between long-term survival and (1) body mass at fledging, and (2) date of fledging.

FEARE, C. J., Marine Ornithology 30: 46-47