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The effects of anthropogenic habitat modification are evident on tropical Pacific islands where forests have been extensively converted to plantations of Coconut Palm {Cocos nucífera). We evaluated resource selection in the critically endangered Tuamotu Kingfisher {Todiramphus gambieri gertrudae), which is confined to a single population on the low-elevation island of Niau Atoll in French Polynesia. Our analyses indicate that resources associated with foraging underlie space use and habitat selection of Tuamotu Kingfishers at multiple spatial scales. At the island scale, the occurrence of the species was best predicted by habitat features associated with foraging opportunities, including agricultural coconut forest with open understory, hunting perches, and exposed ground. Conversely, the species' distribution was negatively associated with undisturbed vegetation, including primary feo forest and fallow coconut plantation. At the home-range scale, utilization distributions of radiomarked Tuamotu Kingfishers also indicated that birds selected agricultural coconut forest and least preferred native feo forest. Observations further indicated that foraging birds selected coconut plantations managed with prescribed burning for hunting. The Tuamotu Kingfisher is a rare example of a threatened tropical species that likely benefits from agricultural management, and our findings provide support for conservation strategies based on establishing rescue populations on other islands with coconut plantations. We suggest that incorporating agricultural coconut forests into conservation planning could help prevent the extinction of several kingfisher species that historically relied on the natural broadleaf habitats that are now almost entirely absent from insular Pacific Oceania. Les plantations de cocotiers comme habitat d'une espèce en danger critique d'extinction, Todiramphus gambieri gertrudaeRÉSUMÉ.-Les effets de la modification anthropique de l'habitat sont évidents sur les iles tropicales du Pacifique où les forêts ont été extensivement converties en plantations de Cocos nucifera. Nous avons évalué la sélection des ressources chez Todiramphus gambieri gertrudae, une espèce en danger critique d'extinction limitée à une seule population sur l'ile à basse altitude de Niau Atoll, en Polynésie française. Nos analyses indiquent que les ressources associées à la quête de nourriture sont à la base de l'utilisation de l'espace et de la sélection de l'habitat par cette espèce à plusieurs échelles spatiales. À l'échelle de l'ile, les caractéristiques de l'habitat associées à des opportunités d'alimentation, telles que les plantations de cocotiers avec un sous-étage ouvert, des perchoirs de chasse et un sol exposé, sont les facteurs qui permettent le mieux de prédire la présence de l'espèce. À l'inverse, la répartition de l'espèce était négativement associée à une végétation non perturbée, telle que les forêts primaires et les plantations de cocotiers en jachère. À l'échelle du domaine vital, la répartition des individus munis d'émet...

The introduction of mammals on oceanic islands currently threatens or has caused the extinction of many endemic species. Cats and rats represent the major threat for 40 % of currently endangered island bird species. Direct (predation) and/or indirect (exploitative competition for food resource) trophic interactions are key mechanisms by which invaders cause the decrease or extinction of native populations. Here, we investigated both direct and indirect trophic interactions amongst four predator species (i.e. animals that hunt, kill and feed on other animals), including three introduced mammals (Felis silvestris catus, Rattus rattus and A peer-reviewed open-access journal NeoBiotaDiane Zarzoso-Lacoste et al. / NeoBiota 53: 61-82 (2019) 62Rattus exulans) and one critically endangered native bird, the Niau kingfisher (Todiramphus gertrudae). All four species' diets and prey availability were assessed from sampling at the six main kingfisher habitats on Niau Island during the breeding season. Diet analyses were conducted on 578 cat scats, 295 rat digestive tracts (218 R. exulans and 77 R. rattus) and 186 kingfisher pellets. Despite simultaneous use of morphological and PCR-based methods, no bird remains in cat and rat diet samples could be assigned to the Niau kingfisher, weakening the hypothesis of current intense predation pressure. However, we determined that Niau kingfishers mainly feed on introduced and/or cryptogenic prey and highlighted the potential for exploitative competition between this bird and both introduced rat species (for Dictyoptera, Coleoptera and Scincidae). We recommend removing the cats and both rat species, at least within kingfisher breeding and foraging areas (e.g. mechanical or chemical control, cat sterilisation, biosecurity reinforcement), to simultaneously decrease predation risk, increase key prey availability and boost kingfisher population dynamics.

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A wide range of threats affect populations of Pacific island birds and conservationists have been challenged to identify factors upon which to focus management. The Tuamotu kingfisher (Todiramphus gambieri) is one of the most endangered vertebrate species in the world, yet little has been published about basic biology or causes of the population decline. We used 4 years of mark-resight and territory resource information to model survival in juvenile and adult Tuamotu kingfishers. Annual survival of adult males (f ¼ 0.77) was similar to congeneric species, whereas survival of adult females (f ¼ 0.40) and juveniles (f ¼ 0.12) was much lower. The best-supported survival model indicated adult female survival was positively related to territory size, whereas adult male survival was negatively related to atoll forest within territories. We used parameter estimates from survival models in a life-stage simulation analysis to evaluate the relative influence of vital rates and territory habitats on population processes. Results indicated that adult female and juvenile survival had the greatest impact on Tuamotu kingfisher populations, accounting for 58% and 32% of variation in the finite rate of population increase, respectively. Nocturnal predation by rats (Rattus spp.) on incubating kingfishers may explain the lower survival of females than males, whereas juvenile birds may be especially vulnerable to predation by cats (Felis catus). Thus, conservation management for Tuamotu kingfishers should include use of metal guards on cavity trees to protect nests and incubating females, and control predator access during fledging periods. ß 2012 The Wildlife Society.