Hatching, fledging success and thermoregulatory behaviors of roof-nesting least terns (Sterna antillarum)

Least Terns (Sterna antillarum) have recently shifted from traditional beach nesting sites to flat gravel roofs in parts of their range. In an attempt to determine whether the thermal environment of novel roof sites contributes to nesting success relative to that of traditional sites, hatching and fledging success and fifteen possible thermoregulatory behaviors of roof-nesting Least Terns were examined at four sites in Palm Beach County, Florida in 1992. The mean numbers of chicks and fledglings produced/nest (1.13 and 0.70, respectively) were significantly higher than those reported in other recent studies, indicating that nesting on some roofs is successful and may be a good alternative to beach locations. There was no difference between equivalent temperatures at the roofs and at a nearby beach, thereby suggesting that the new thermal environments of roofs do not adversely influence hatching and fledging success in Least Terns.