Notes on the biology of the threatened Island Thrush Turdus poliocephalus xanthopus in New Caledonia

• Published in: Bird Conservation International
• Main Authors: Villard, Pascal, Duval, Thomas, Papineau, Christian, Cassan, Jean-Jérôme, Fuchs, Jérôme
• Other Authors: Institut de Systématique, Evolution, Biodiversité (ISYEB ), Muséum national d'Histoire naturelle (MNHN)-École Pratique des Hautes Études (EPHE), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: [SDE]Environmental Sciences; Merle; Rattus rattus
• Online Access: https://hal.science/hal-03787069; https://doi.org/10.1017/S0959270919000091

International audience Summary Three subspecies of Island Thrush Turdus poliocephalus were historically found in New Caledonia. All these subspecies were considered extinct until 1978, when T. p. xanthopus was rediscovered on two small islands, Néba (∼ 3.5 km 2 ) and Yandé (∼ 13 km 2 ). On Néba, we estimated the population at 44–58 individuals. This Island Thrush population is dependent on the coastal forest, the richest habitat for invertebrates. However, the coastal forest habitat has been degraded in quality and extent. The Island Thrush forages in the litter by removing leaves with its bill. Fruits (diameter < 10 mm), picked from trees and swallowed whole, are also a significant component of its diet. Néba and Yandé are currently free of two nest predator species, the black rat Rattus rattus and the New Caledonian Crow Corvus moneduloides . On Néba, a low breeding success rate of 15.4% was found. To ensure conservation of these relict thrush populations, two actions at least should be implemented: setting up a biosecurity programme to keep islands free of black rats and increasing the area of coastal forest. The latter could be done by cutting down coconut trees in abandoned groves and planting tree species used by the Island Thrush to provide shade, fruits, good leaf litter, and nest support. Résumé Trois sous-espèces de Merle des Iles Turdus poliocephalus existaient historiquement en Nouvelle-Calédonie. Ces sous-espèces étaient considérées comme éteintes jusqu’en 1978, quand T. p. xanthopus a été redécouvert sur deux petites îles, Néba (∼ 3,5 km 2 ) et Yandé (∼ 13 km 2 ). Sur Néba, nous estimons la population entre 44 et 58 individus. Cette population de merle des Iles dépend de la forêt littorale, l’habitat le plus riche en invertébrés. Pourtant, la forêt littorale a été dégradée en qualité et en taille. Le Merle des Iles se nourrit dans la litière en soulevant les feuilles avec son bec. Les fruits (diamètre <10 mm), cueillis dans les arbres et avalés en entier font également partie de son ...