D.a Monticelli and J.A.c Ramos (2007)
Plumage characteristics and return rate of one-year-old tropical Roseate Terns
Waterbirds, 30(1):58-63.
We report an unusually high return rate (16\%) of one-year-old Roseate Terns (Sterna dougalli) to their natal colony on Aride Island, Seychelles, in 2005. Detailed accounts of these birds are provided in terms of timing of arrival, breeding status, and plumage characteristics, and compared with those of two other age classes (2-year-olds and 3 to 6 year-olds) in the same colony and with temperate populations. One-year-old individuals returned on average three weeks later than older birds and did not attempt to breed. Their immature plumage dress ('portlandica phase') differed from their one-year-old temperate counterparts, with most birds showing several characteristics of adults in full breeding plumage, such as red bill and red legs, long tail-streamers, and absence of a dark carpal bar. Contrary to expectations from temperate studies, nonbreeding two-year-old individuals did not retain any characteristic of the portlandica plumage, and were virtually inseparable from breeding adults. The ad hoc return rate of Roseate Tern one-year-olds found in this particular year is high compared to recapture/resighting data from colonies in temperate areas, but is comparable to observations made at other tropical (Caribbean) breeding colonies. Altogether, these findings suggest that tropical Roseate Terns are prone to return to their natal site earlier than their temperate counterparts, and show a more rapid acquisition of the adult plumage. This may be especially the case in years of good food supply conditions, since the 2005 event coincided with the two (2004-2005) of highest marine productivity recorded in the vicinity of Aride Island over the 1997-2005 period.
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