Annual population growth in songbirds can be particularly sensitive to post-fledging survival, but research and management are frequently biased toward the nesting stage. Post-fledging information is particularly scarce for species breeding in desert bird communities, many of which have collapsed in recent decades. During 2017-2019 at Sevilleta National Wildlife Refuge, New Mexico, USA, we used radio telemetry to monitor survival, movements, and habitat associations of 90 fledgling Gray Vireos (Vireo vicinior), a desert-dwelling species of conservation concern. We used logistic exposure models to investigate the relationship between fledgling survival and habitat features at two spatial scales. Overall, we estimated that 51 ± 8% of fledglings survived the monitoring period. All mortalities occurred during the first 12 days post-fledging and were attributed to predation and environmental exposure. In daily survival models focused on predation mortalities, age was the strongest predictor of survival. Daily survival rate was not related to any habitat variables we measured. Percent tree cover used by birds during the first 12 days post-fledging was similar to that of nesting sites and greater than that of random locations. Similarly, fledglings occupied individual trees and shrubs with lateral vegetation cover similar to that of nest locations. Minimum daily distance traveled, distance from nests, and variance associated with these measures, all increased with age. Except for the use of a larger area, habitats used by Gray Vireos during the post-fledging period were similar to those used for nesting in our study population, indicating that maintenance of large patches of moderately dense juniper is desirable for this species. More study is needed from populations in less pristine and more heterogeneous landscapes. More broadly, given the importance of first-year survival in demographic models and the declines of dryland birds, information is needed on the postfledging period of many desert songbirds. Survie après l'envol, déplacements et associations avec l'habitat de Viréos gris au Nouveau-MexiqueRESUME_. La croissance annuelle des populations de passereaux peut être particulièrement sensible à la survie après l'envol, mais la recherche et la gestion sont souvent orientées vers le stade de la nidification. Les données suivant l'envol sont particulièrement rares pour les espèces nichant au sein de communautés d'oiseaux de désert, dont beaucoup se sont effondrées au cours des dernières décennies. En 2017-2019, au Sevilleta National Wildlife Refuge au Nouveau-Mexique (États-Unis), nous avons utilisé la radiotélémétrie pour suivre la survie, les déplacements et les associations avec l'habitat de 90 Viréos gris (Vireo vicinior) prêts à l'envol, une espèce désertique dont la conservation est préoccupante. Nous avons utilisé des modèles logistiques d'exposition pour étudier la relation entre la survie des oisillons et les caractéristiques de l'habitat à deux échelles spatiales. Dans l'ensemble, nous avons calculé que 51 ±...

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Brood parasitism can have major detrimental effects on the fitness of reproducing songbirds and often contributes to nest failure. As the Gray Vireo (Vireo vicinior) suffers high rates of brood parasitism by the Brown-headed Cowbird (Molothrus ater), we hypothesized that vireos might choose nest sites selectively to thwart cowbird parasitism. To investigate this question, we measured and compared vegetative and spatial attributes of nest sites in a known breeding population of the Gray Vireo on the Sevilleta National Wildlife Refuge, New Mexico, in 2017 and 2018. Specifically, we compared parasitized and unparasitized nests with respect to the nest’s height and the average height, diameter, and foliage density of the nest tree. We also compared the spatial attributes of the nearest neighboring nest, nearest parasitized nest, and the density of surrounding juniper trees within 50 m of a nest. Interestingly, among none of the variables measured did we find an association with the incidence of brood parasitism, suggesting that nest parasitism might be more strongly linked to other larger-scale ecological or behavioral variables.