ABSTRACT. We describe a new collaborative network, the Motus Wildlife Tracking System (Motus; https://motus.org), which is an international network of researchers using coordinated automated radio-telemetry arrays to study movements of small flying organisms including birds, bats, and insects, at local, regional, and hemispheric scales. Radio-telemetry has been a cornerstone of tracking studies for over 50 years, and because of current limitations of geographic positioning systems (GPS) and satellite transmitters, has remained the primary means to track movements of small animals with high temporal and spatial precision. Automated receivers, along with recent miniaturization and digital coding of tags, have further improved the utility of radio-telemetry by allowing many individuals to be tracked continuously and simultaneously across broad landscapes. Motus is novel among automated arrays in that collaborators employ a single radio frequency across receiving stations over a broad geographic scale, allowing individuals to be detected at sites maintained by others. Motus also coordinates, disseminates, and archives detections and associated metadata in a central repository. Combined with the ability to track many individuals simultaneously, Motus has expanded the scope and spatial scale of research questions that can be addressed using radio-telemetry from local to regional and even hemispheric scales. Since its inception in 2012, more than 9000 individuals of over 87 species of birds, bats, and insects have been tracked, resulting in more than 250 million detections. This rich and comprehensive dataset includes detections of individuals during all phases of the annual cycle (breeding, migration, and nonbreeding), and at a variety of spatial scales, resulting in novel insights into the movement behavior of small flying animals. The value of the Motus network will grow as spatial coverage of stations and number of partners and collaborators increases. With continued expansion and support, Motus can provide a framework for global collaboration, and a coordinated approach to solving some of the most complex problems in movement biology and ecology.Le Système de suivi de la faune Motus : un réseau de recherche collaboratif visant à mieux comprendre le déplacement des animaux RÉSUMÉ. Le Système de suivi de la faune Motus (Motus; https://motus.org), un nouveau réseau collaboratif de chercheurs internationaux, repose sur un ensemble coordonné de stations automatisées de radiotélémétrie pour étudier le déplacement de petits organismes volant, comme les oiseaux, les chauves-souris et les insectes, aux échelles locales et régionales, et à celle de l'hémisphère. Pierre angulaire pour les études de suivi depuis plus de 50 ans, la radiotélémétrie est encore le principal moyen de suivre le déplacement de petits animaux avec une grande précision temporelle et spatiale, en raison des limites que présentent les émetteurs basés sur le système de positionnement géographique (GPS) ou satellite. Des stations réceptrices automatisées,...

During the non-breeding season, many species of territorial migratory birds exhibit a non-random pattern of habitat distribution, with males and females occupying di erent habitats. In this study, we examined possible physiological consequences arising from such habitat segregation in one migrant passerine species, the American redstart (Setophaga ruticilla), on its nonbreeding grounds in Jamaica, West Indies. For 2 years, we measured concentrations of corticosterone, at the time of capture (baseline) and 30 min after capture (pro®le of acute corticosterone secretion), in redstarts in two distinct habitats, one occupied predominately by males and one mostly by females. All redstarts in both habitat types exhibited similar concentrations of baseline corticosterone levels in fall (October), whereas in spring (March±April), redstarts in female-biased habitat exhibited signi®cantly higher baseline levels regardless of age or sex. In fall, all individuals in both habitats exhibited signi®cant increases in corticosterone concentration with capture and handling, but in spring only redstarts (both sexes) in male-biased habitat continued to exhibit acute corticosterone secretion. Redstarts in female-biased habitat had elevated baseline corticosterone levels and reduced acute corticosterone secretion. In spring, baseline corticosterone concentration was negatively correlated with body mass, suggesting muscle catabolism associated with high corticosterone concentrations or possibly that birds are leaner as a result of increased foraging e ort. These results indicate that redstarts (primarily females) in female-biased habitats su ered a decline in physiological condition, which could in turn in¯uence their departure schedules, migration patterns and even their condition and arrival schedules on the breeding grounds. Thus, segregation of populations into habitats of di erent quality during the nonbreeding period may have rami®cations throughout the annual cycle of such migratory species. Furthermore, these results show the usefulness of plasma corticosterone levels as indicators of physiological condition and thus habitat quality for birds during the non-breeding period.

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Summary 1.Telomeres are long repetitive noncoding sequences of DNA located at the ends of chromosomes. Recently, the study of telomere dynamics has been increasingly used to investigate ecological questions. However, little is currently known about the relationships that link environmental conditions, telomere dynamics and fitness in wild vertebrates. 2. Using a small migratory bird (American redstart, Setophaga ruticilla), we investigated how telomere dynamics can be affected by non-breeding habitat quality and to what extent telomere length can predict the return rate of males. 3. We show that telomeres shorten in most individuals over a 1-year period and, importantly, that telomeres of individuals wintering in a low-quality habitat shorten more than those of individuals wintering in a high-quality habitat. 4. In addition, we found that longer telomeres are associated with a higher return rate than shorter telomeres, although the relationship between return rate and telomere length did not depend on habitat quality. 5. Our study suggests that telomere dynamics are affected by environmental conditions and are related to indices of fitness in a migratory bird species.