Survival of fallen and returned rooftop nesting Least Tern chicks

Abstract

Beach habitat is increasingly degraded and disturbed, and many species of Larids (gulls, terns, and skimmers) have adapted to nesting on gravel rooftops. In the southeastern United States, the most common rooftop nester is the Least Tern (Sternula antillarum), and rooftop tern colonies are generally as productive as beach colonies. One problem with rooftop nesting is that chicks often fall from the roofs and will likely die if not rescued. Fallen chicks can be taken to wildlife rehabilitators and if they survive, be released on their own, but they will not receive the substantial pre-and post-fledgling parental care that Least Tern parents provide. We explored the success of placing chicks back on rooftops until they fledge and are able to travel to a staging beach. To determine long-term survival of these birds, from June 2011-July 2019, we uniquely banded 168 fallen Least Tern chicks in the Tampa Bay, Florida (USA) region and placed them back on the rooftops. From 2011-2022, we resighted banded birds on beaches, piers, and rooftops throughout Florida during the breeding season. We used the Cormack-Jolly-Seber model in Program Mark to estimate survival of juveniles and adults. The base model, where time was held constant for apparent survival and of both age classes and recapture rates, was the most parsimonious. We resighted 50 out of the 167 banded adult Least Terns a total of 347 times from 2012-2021. Apparent survival for fallen juvenile Least Terns was 0.387 ± 0.049 and 0.819 ± 0.032 for adult terns. There are no other studies of survival for juvenile Least Terns, but a closely related species had a slightly higher apparent survival. Adult survival in our study was comparable to that found in other similar Least Tern studies. This indicates that putting fallen Least Tern chicks back onto rooftops is a sound management strategy and should be explored for other species of seabirds. Survie d'oisillons de Petite Sterne nichant sur les toits, tombés et remis au nidRÉSUMÉ. En tant qu'habitat, les plages sont de plus en plus dégradées et de nombreuses espèces de Laridés (goélands, mouettes, sternes et becs-en-ciseaux) se sont adaptées à la nidification sur les toits de gravier. Dans le sud-est des États-Unis, l'oiseau nicheur le plus commun sur les toits est la Petite Sterne (Sternula antillarum), et les colonies qui s'y établissent sont généralement aussi productives que celles qui sont établies sur les plages. L'un des problèmes de la nidification sur les toits est que les oisillons tombent souvent et risquent de mourir s'ils ne sont pas secourus. Les oisillons tombés peuvent être transportés à un centre de réhabilitation de la faune et, s'ils survivent, être relâchés, mais ils ne recevront pas les soins parentaux importants avant et après la nidification que les parents de Petite Sterne prodiguent. Nous avons étudié la possibilité de remettre sur les toits les poussins tombés jusqu'à ce qu'ils s'envolent et soient capables de se rendre sur une plage. De juin 2011 à juillet 2019, pour déterminer la survie à long...