Kelp Geese (Chloephaga hybrida) and Flightless Steamer-Ducks (Tachyeres pteneres) in the Beagle Channel: the importance of islands in providing nesting habitat

M LILJESTHRÖM; A SCHIAVINI; R SAENZ SAMANIEGO; L FASOLA; A RAYA REY

WILSON BULLETIN

wilson ornithologial society

Año: 2013 vol. 125 p. 583 - 591

0043-5643

We describe the nest-site characteristics and breeding habitat use of Kelp Geese (Chloephaga hybrida)and Flightless Steamer-Ducks (Tachyeres pteneres) along 137 km of coastline on the northern shore of the Beagle Channel,Argentina, and 87 km of island coastline. We examined the importance of vegetation cover, predation, and tourism on thedistribution of nests among islands. We found all nests only on islands and islets. Nesting sites for both species werestrongly associated with higher proportions of high vegetation cover (shrubs). Kelp Geese were also associated with theabsence of terrestrial predators. Tourist presence on islands was not associated with the occurrence of nests for eitherspecies. The northern coasts of the Beagle Channel and the islands and islets along the channel have similar habitat types.However, the islands and islets are relatively inaccessible to mammalian terrestrial predators compared to the coast of thechannel where terrestrial predators are frequently recorded. Therefore, islands and islets seem to provide a relatively safenesting habitat for Kelp Geese and Flightless Steamer-Ducks by offering refuge mainly from ground predators.Additionally, habitat changes caused by increased human disturbance along the northern shore of the Beagle Channel mayalso explain the presence of nests only on islands and islets, though further studies are needed to assess these effects. Thisstudy contributes new information on the breeding habitat and nesting sites of Flightless Steamer-Ducks and Kelp Geese inthe Beagle Channel, to assist in the identification of priority breeding sites and habitats to protect. Also, it highlights theimportance of islands and islets of the Beagle Channel as safe breeding refuge for these two ground nesting seabirds.