Using Isotopic Variance to Detect Long-Distance Dispersal and Philopatry in Birds: An Example with Ovenbirds and American Redstarts (original) (raw)
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An evaluation of isotopic (δ2H) methods to provide estimates of avian breeding and natal dispersal
Ecosphere, 2019
Natal and breeding dispersal represents an important component of animal demography and metapopulation theory. This phenomenon also has implications for conservation and management because understanding movements of individuals potentially allows the identification of key habitats that may be acting as population sources or sinks. Intrinsic markers such as stable isotope abundance in tissues that can be associated with provenance can provide a coarse but pragmatic solution to understanding such movements. Different methodologies have been proposed to quantify natal and breeding dispersal by using stable isotope analyses of keratinous tissues (hair, feathers), each of them with their own advantages and limitations. Here, we compared results provided by four different methods to estimate dispersal (three already published and one novel) in animals using stable isotope measurements. We used a single large dataset of feather δ2H values from golden‐winged warblers (Vermivora chrysoptera)...
2013
Northern Saw-whet Owls (Aegolius acadicus) breed throughout the boreal forest of North America, but little is known about their population trends or distribution within this region. Analysis of stable hydrogen isotopes (δ 2 H) in feathers can delineate origins of a variety of avian migrants, but raptors are reported to have high intrafeather isotopic variance and mean δ 2 H values higher than predicted from δ 2 H isoscapes specific to raptor feathers, making assignment of geographic origin sometimes difficult. We examined the applicability of δ 2 H analysis of sawwhet owl feathers to delineating origins of migrants and to assessing differences in the migratory behavior of adult and young owls by using multiple generations of feathers from owls captured during fall migration at the Delta Marsh Bird Observatory, Manitoba, 2006Manitoba, -2007 Values of δ 2 H in saw-whet owl feathers were higher than predicted from a δ 2 H isoscape specific to raptor feathers and from patterns of movements inferred from analysis of band recoveries. This effect was pronounced in adults, while values of δ 2 H in feathers of hatching-year owls fell primarily within the range predicted for the boreal forest northwest of Delta Marsh. Significant differences in δ 2 H values among feather generations suggest that physiological or behavioral differences between adults and young give rise to greater 2 H enrichment in adult feathers. These results indicate that current δ 2 H isoscapes for feathers cannot be used to track adult saw-whet owls reliably and further research into the mechanisms of 2 H enrichment in owl feathers is required.
Journal of Field Ornithology, 2014
relativas obtenida en nuestros muestreos sobre las aves que anidan en América del norte en nuestros modelos de asignación bayesiana, generalmente resulto en una reducción en asignación de potencialesáreas en los lugares de anidación. Sin embargo, herramientas adicionales que limiten la variación en longitud tales como marcadores de ADN u otros isotopos pueden ser requeridos para establecer orígenes de anidación o muda de especies con una amplia distribución longitudinal. La aproximación isotópica se puede usar como una forma rápida de establecer patrones básicos de conectividad migratoria en muchas especies y poblaciones. Proponemos un esfuerzo de muestreo coordinado y a gran escala en lasáreas invernales para establecer un atlas isotópico de conectividad migratoria para los migrantes Neotropicales de América del norte y sugerir que la varianza isotópica puede considerarse como una valiosa medida métrica para cuantificar la conectividad migratoria. Esta iniciativa puede servir como una estrategia base para guiar esfuerzos futuros que involucren isotopos estables, geolocalizadores sensibles a la luz y otras tecnologías.
Avian Conservation and Ecology, 2015
. Predicting origins of passerines migrating through Canadian migration monitoring stations using stable-hydrogen isotope analyses of feathers: a new tool for bird conservation. Avian Conservation and Ecology 10(1): 3. http://dx.ABSTRACT. The Canadian Migration Monitoring Network (CMMN) consists of standardized observation and migration count stations located largely along Canada's southern border. A major purpose of CMMN is to detect population trends of migratory passerines that breed primarily in the boreal forest and are otherwise poorly monitored by the North American Breeding Bird Survey (BBS). A primary limitation of this approach to monitoring is that it is currently not clear which geographic regions of the boreal forest are represented by the trends generated for each bird species at each station or group of stations. Such information on "catchment areas" for CMMN will greatly enhance their value in contributing to understanding causes of population trends, as well as facilitating joint trend analysis for stations with similar catchments. It is now well established that naturally occurring concentrations of deuterium in feathers grown in North America can provide information on their approximate geographic origins, especially latitude. We used stable hydrogen isotope analyses of feathers (δ²H f ) from 15 species intercepted at 22 CMMN stations to assign approximate origins to populations moving through stations or groups of stations. We further constrained the potential catchment areas using prior information on potential longitudinal origins based upon bird migration trajectories predicted from band recovery data and known breeding distributions. We detected several cases of differences in catchment area of species passing through sites, and between seasons within species. We discuss the importance of our findings, and future directions for using this approach to assist conservation of migratory birds at continental scales. Prédiction de la provenance de passereaux détectés aux stations canadiennes de surveillance des migrations grâce à l'analyse d'isotopes stables d'hydrogène présents dans les plumes : un nouvel outil pour la conservation des oiseaux RÉSUMÉ. Le Réseau canadien de surveillance des migrations (RCSM) est composé de stations de dénombrement d'oiseaux en migration dont les observations sont standardisées; ces stations sont surtout situées le long de la frontière sud du Canada. Un des objectifs principaux du RCSM est de détecter la tendance des populations de passereaux migrateurs qui nichent principalement dans la forêt boréale et qui sont moins bien suivis par le Relevé des oiseaux nicheurs (BBS) d'Amérique du Nord. Une des lacunes principales de cette approche de suivi est qu'on ne connait pas clairement de quelle région géographique de la forêt boréale est issue la tendance générée pour chaque espèce à chaque station ou groupe de stations. L'information relative à la provenance régionale des oiseaux va permettre d'améliorer considérablement la valeur des données récoltées par le RCSM parce qu'elles pourront alors contribuer à élucider les causes des tendances de population, de même que faciliter l'analyse conjointe de tendances issues de stations pour lesquelles les oiseaux auraient la même provenance. On sait maintenant que les concentrations naturelles de deutérium dans les plumes ayant poussé en Amérique du Nord peuvent fournir des renseignements à propos de l'origine géographique approximative des oiseaux, en particulier la latitude. Nous nous sommes servi d'analyses d'isotopes stables d'hydrogène (δ²Hf) provenant de plumes appartenant à 15 espèces détectées à 22 stations du RCSM pour déterminer la provenance approximative des oiseaux se déplaçant par les stations ou des groupes de stations. Nous avons ensuite restreint les provenances potentielles des oiseaux au moyen d'information touchant l'origine latitudinale potentielle fondée sur des trajectoires de migration prédites à partir de données de récupération de bagues et d'aires de nidification connue. Nous avons détecté plusieurs cas de provenances régionales différentes d'espèces se déplaçant par les stations, et entre les saisons pour une même espèce. Nous discutons de l'importance de nos résultats et faisons des recommandations pour l'emploi futur de cette approche afin de contribuer à la conservation des oiseaux migrateurs aux échelles continentales.
Ecological Applications, 2017
The stochastic and infrequent nature of long-distance dispersal often makes it difficult to detect. We quantified the frequency, distance, and timing of long-distance dispersal in a nonmigratory, secretive wetland bird, the California Black Rail (Laterallus jamaicensis coturniculus), between an inland and a coastal metapopulation separated by greater than 100 km. Using 15 microsatellites in conjunction with stable carbon, nitrogen, and sulfur isotopes, we classified Rails as residents of their capture population, recent migrants that dispersed to their capture population less than one year before capture, established migrants that dispersed to their capture population more than one year before capture, and seasonal migrants that dispersed away from their capture population to forage, but returned the next season. Most Rails (195 of 204, or 95.6%) were classified as residents, but we detected two established migrants that had moved >100 km more than a year before capture. Seven Rails appeared to be seasonal migrants, but comparisons of feather isotope values with isotope values from wetland soils indicated that the isotope values in the feathers of these Rails likely resulted from natural environmental variation (e.g., source element effects) rather than long-distance dispersal of individuals. Thus, these seven Rails were most likely misassigned by isotopic population assignments due to small-scale variation in the isoscape. Using genetic data in conjunction with isotopic data allowed us to not only infer the timing of long-distance dispersal events, but to successfully track long-distance movements of nonmigratory Rails between metapopulations even when environmental variation of isotopes occurred across small spatial scales.
PLoS ONE, 2014
Adult birds tend to show high fidelity to their breeding territory or disperse over relatively short distances. Gene flow among avian populations is thus expected to occur primarily through natal dispersal. Although natal dispersal is a critical demographic process reflecting the area over which population dynamics take place, low recapture rates of birds breeding for the first time have limited our ability to reliably estimate dispersal rates and distances. Stable isotope approaches can elucidate origins of unmarked birds and so we generated year-and age-specific d 2 H and d 34 S feather isoscapes (ca. 180 000 km 2 ) of coastal-breeding Ovenbirds (Seiurus aurocapilla) and used bivariate probability density functions to assign the likely natal areas of 35 males recruited as first-year breeders into a population located in northwestern New Brunswick, Canada. Most individuals (80-94% depending on the magnitude of an age correction factor used; i.e. 28-33 out of 35) were classified as residents (i.e. fledged within our study area) and estimated minimum dispersal distances of immigrants were between 40 and 240 km. Even when considering maximum dispersal distances, the likely origin of most first-year breeders was,200 km from our study area. Our method identified recruitment into our population from large geographic areas with relatively few samples whereas previous mark-recapture based methods have required orders of magnitude more individuals to describe dispersal at such geographic scales. Natal dispersal movements revealed here suggest the spatial scale over which many population processes are taking place and we suggest that conservation plans aiming to maintain populations of Ovenbirds and ecologically-similar species should consider management units within 100 or at most 200 km of target breeding populations.