Predicting origins of passerines migrating through Canadian migration monitoring stations using stable-hydrogen isotope analyses of feathers: a new tool for bird conservation

Abstract

. 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 oiseauxRÉSUMÉ. 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 R...

Biased representation of disturbance rates in the roadside sampling frame in boreal forests: implications for monitoring design

“…In addition, roads in several regions may be too dangerous to sample via roadside sampling. Thus, it is apparent that trends for these strata will require reliance either on off-road point counts or BBS style surveys (e.g., via all-terrain vehicle) such as those conducted for bird atlases (Blancher et al 2009), dedicated regional monitoring programs (e.g., Machtans et al 2014), or reliance on trends from the Christmas Bird Count (Niven et al 2004) or migration monitoring in combination with methods to infer catchment areas (Hobson et al 2015). As such, it would be beneficial to build on other work (e.g., Sólymos et al 2013, Amundson et al 2014 to develop and validate a framework for trend estimation from combining on-road and off-road point counts.…”

Banding data reveal bias in age-class sampling of songbirds during spring migration

“…, Hobson et al. ), banding datasets do not represent a population, per se. I use that term here consistent with using the dataset to generate survival estimates for a generic migratory passerine.…”

Temporal changes in avian abundance in aspen-dominated boreal mixedwood forests of central Saskatchewan, Canada

“…Following Blancher et al (2009), we suggest that trend estimates from repeating historic surveys can be used in concert with regional BBS data and other monitoring programs such as migration monitoring (Hobson et al 2015) to provide a weightof-evidence approach to assessing overall support for changes in species' status where sampling may otherwise be sparse. We recommend that effort be put into identifying historic studies with ancillary data that could be used to further examine the factors driving changes in avian populations.…”