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Molecular studies support the hypothesis that Corsica Island was a glacial refugium for a number of forest birds during the Pleistocene. We focused on the Corsican nuthatch (Sitta whiteheadi), an endemic passerine strongly associated with the laricio pine (Pinus nigra laricio). The range of laricio pine has been impacted by the Pleistocene glacial periods and forest has been recently fragmented by cutting and fires. Using both molecular (mitochondrial and nuclear) and morphological characters, we assessed the variation within the nuthatch population. Our results are consistent with the hypothesis that the Corsican nuthatch endured through the late Pleistocene and Holocene climatic variations, and sustained the subsequent cycles of forests reduction/expansion. The results also suggest that the recent anthropization of the landscape resulted in the isolation of a cluster of populations in the northern part of the island. The fragmentation of the habitat of the nuthatch may impede the future of the bird by creating isolated population units between which the gene flow is reduced.

SummaryEndemic to the island of Corsica in the western Mediterranean, the Corsican NuthatchSitta whiteheadionly occupies mature stands of Corsican PinePinus nigra lariciowhich cover a very small area. We present estimates of the distribution and population size of the Corsican Nuthatch, based on both field investigation and analysis of vegetation maps for the 103 county and municipality forests identified. Between spring 1997 and summer 2008, 48 forests were systematically investigated to map nuthatch territories, requiring 20 months of fieldwork. In the 55 forests not explored, we estimated the number of territories from analysis of digital maps with a calculated mean density from six spot-mapping censuses previously made in mature forests. The total estimated number was estimated to be 1,557-2,201 territories, distributed across 45 forest fragments (= group of connected stands) totalling 185 km2. At distances varying from 250 m to 16 km from each other, fragments were separated by unfavourable vegetation (shrubs, trees other than pines) or rocky outcrops. The area of these fragments varied from seven to 3,159 ha. Of the 45 fragments, 19 held fewer than 10 nuthatch pairs, 20 had 10–99 territories, and only six had more than 100 territories. We suggest that nuthatch numbers have declined by 10% in the past 10 years because of a reduction in suitable habitat due to fires and logging. The Corsican Nuthatch currently fulfils the criteria established by IUCN to qualify as “Vulnerable”.

SummaryThe distribution of Tahitian landbirds in the early twentieth century and at presented here together with maps. Three categories may be recognized: (1) species with a declining distribution owing to changes in habitats (Green-backed Heron), (2) stable or increased species, including local and earlier introduced species, and (3) newly introduced species (Zebra Dove, Red-vented Bulbul, Silvereye and Crimson-backed Tanager). Moreover, owing to their low population numbers, two species, the Pacific Pigeon and the Tahiti Monarch, are on the verge of extinction even if their distribution has not changed notably during this century.Les repartitions des oiseaux terrestres reproducteurs de Tahiti, au début et à la fin du 20e siècle, sont présentées sous forme de cartes. Trois catégories d'espèces sont dis-tinguées: (1) espèce dont la répartition est en déclin a la suite des modifications d'habitats (Héron vert), (2) espèces stable ou en légère augmentation, chez qui on trouve des oiseaux locaux et des oiseaux introduits, et enfin (3) les espèces introduites durant le 20e siècle (Tourterelle striée, Bulbul à ventre rouge, Zosterops à poitrine grise et Tangara cramoisi). II apparaît que deux espèces, le Carpophage du Pacifique et le Monarque de Tahiti, sont aujourd'hui très menacées, même si leur répartition n'a pas régressé d'une façon significative.

SummaryA survey in December/January 1989/1990 revealed that an estimated 274 Rapa Fruit-doves Ptilinopus huttoni remain in Rapa's last (and fragmented) 292 ha of forest. This suggests no serious decline since 1974, but the forests continue to be degraded and cleared, and action to preserve key sites is urgently needed.Un recensement en décembre/janvier 1989/1990 montra qu'un nombre estimé de 274 Ptilopes de Hutton Ptilinopus huttoni survivent dans les derniers 292 ha de forêt fragmen-tee sur l'île de Rapa. Ceci ne suggére aucun déclin important depuis 1974, mais les forêts continuent à être dégradées et coupées, ainsi il devient urgent d'entreprendre des actions pour le sauvegarde des sites clés.