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Wetlands of the Laurentian Great Lakes of North America (i.e. lakes Superior, Michigan, Huron, Erie, and Ontario) provide critical habitat for marsh birds. We used 11 years (2011–2021) of data collected by the Great Lakes Coastal Wetland Monitoring Program at 1,962 point-count locations in 792 wetlands to quantify the first-ever annual abundance indices and trends of 18 marsh-breeding bird species in coastal wetlands throughout the entire Great Lakes. Nine species (50%) increased by 8–37% per year across all of the Great Lakes combined, whereas none decreased. Twelve species (67%) increased by 5–50% per year in at least 1 of the 5 Great Lakes, whereas only 3 species (17%) decreased by 2–10% per year in at least 1 of the lakes. There were more positive trends among lakes and species (n  = 34, 48%) than negative trends (n  = 5, 7%). These large increases are welcomed because most of the species are of conservation concern in the Great Lakes. Trends were likely caused by long-term, cyclical fluctuations in Great Lakes water levels. Lake levels increased over most of the study, which inundated vegetation and increased open water-vegetation interspersion and open water extent, all of which are known to positively influence abundance of most of the increasing species and negatively influence abundance of all of the decreasing species. Coastal wetlands may be more important for marsh birds than once thought if they provide high-lake-level-induced population pulses for species of conservation concern. Coastal wetland protection and restoration are of utmost importance to safeguard this process. Future climate projections show increases in lake levels over the coming decades, which will cause "coastal squeeze" of many wetlands if they are unable to migrate landward fast enough to keep pace. If this happens, less habitat will be available to support periodic pulses in marsh bird abundance, which appear to be important for regional population dynamics. Actions that allow landward migration of coastal wetlands during increasing lake levels by removing or preventing barriers to movement, such as shoreline hardening, will be useful for maintaining marsh bird breeding habitat in the Great Lakes. [ABSTRACT FROM AUTHOR]

Bird species that undertake irruptive migrations are good candidates for assessing density-dependent effects on stopover ecology because the number of birds using stopover sites varies considerably from year to year. Using morphometric data from a 9-year banding program and radiotelemetry (n  = 25 females), we found that increases in the annual density of Northern Saw-whet Owls (NSWO; Aegolius acadicus) encountered at a fall stopover site in Nova Scotia, Canada, were not linked to female body condition or minimum stopover duration. Rather, most NSWO spent no more than 1 or 2 full days at the stopover site following radio-tagging and during their return visits to the site. Body condition indices were highest for NSWO captured near the end of the migration monitoring season, possibly reflecting birds that had recently established wintering ranges and were elevating energy stores. We used breeding abundance indices derived from Birds Canada's Atlantic Nocturnal Owl Survey to help test the hypothesis that irruptive fall migrations in NSWO were driven by elevated breeding productivity and dispersal of immature birds (breeding success hypothesis). Indeed, irruptive fall migrations were characterized by elevated densities of immatures, but not adults, and mean breeding abundance indices for the Maritime provinces during years with irruptive migrations were higher than those for non-irruptive years. We hypothesize that prey abundance during years with irruptive migrations was sufficient to enable high breeding densities and minimize effects of elevated fall densities of NSWO on rates of mass gain and stopover duration. [ABSTRACT FROM AUTHOR]

Global biodiversity is increasingly threatened by the spread of invasive species. Understanding the mechanisms influencing the initial colonization and persistence of invaders is therefore needed if conservation actions are to prevent new invasions or strive to slow their spread. The Eurasian Collared-Dove (Streptopelia decaocto, EUCO) is one of the most successful avian invasive species in North America; however, to our knowledge, no study has simultaneously examined the role that climate-matching, human activity, directional propagation, and local density have in this invasion process. Our research expands upon a cellular-automata-based hierarchical model developed to assess directional invasion dynamics to further quantify the impacts of climate, elevation, and land cover type on the spread of EUCO in North America. Our results suggest that EUCO's dispersal patterns can largely be explained by the effects of habitat, climate, and environmental conditions at different stages of the invasion process rather than some innate preferred north-westerly spread. Specifically, EUCO initially colonized warm and wet grassland habitats and tended to persist in urban areas. We also found that while EUCO were more likely to spread to the northeast of existing habitats, directional preference did not drive persistence and recolonization events. These findings highlight the importance of incorporating both neighborhood effects and environmental factors in the modelling of range-expanding species, adding to the toolset available to researchers to model invasive species spread. Further, our research demonstrates that historical records of invasive species occurrences can provide the data resources needed to disentangle the characteristics driving species invasion and enable predictions that are of critical importance to resource managers. [ABSTRACT FROM AUTHOR]

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Copyright of Global Change Biology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Road mortality is identified as a threat to American badger (Taxidea taxus (Schreber, 1777)) populations across Canada. Understanding habitat selection and movement in relation to roads is therefore vital to their conservation. Using telemetry data and road-kill locations of badgers in southwestern Ontario, we examined the relationship between habitat selection, movement patterns, and roads at three spatial scales. At the study-area scale, we assessed the effects of habitat attributes on burrow site selection. Several individuals placed their burrows closer to primary highways than expected, suggesting that badgers are not sensitive to human disturbances at this scale. Using straight-line movement trajectories between burrows, we analyzed individual movement patterns within home ranges. All badgers showed some degree of road avoidance, either crossing fewer roads or roads that posed lower mortality risk. At the road-crossing scale, we compared landscape features surrounding road-kill locations to random locations along the same roadway. There was a positive relationship between road-kill locations and number of water-based linear features and higher density of hedgerow cover. Our results provide evidence that badger movement is influenced by roads at multiple scales, which has important implications for managers interested in developing road-mitigation strategies for this endangered population. Key words: American badger, Taxidea taxus jacksoni, conservation, movement, roads, species at risk, wildlife--vehicle collisions., Resume : La mortalite routiere constitue une menace pour les populations de blaireaux d'Amerique (Taxidea taxus (Schreber, 1777)) partout au Canada. La comprehension de la selection d'habitats et des deplacements [...]

We review the role of biogeochemical signatures, such as stable isotopes and trace elements, in the cornified claw tissue as a means of studying movement and foraging behaviour of vertebrates because this approach is noninvasive and can capture contemporary and historic signatures. Because biogeochemical techniques are still relatively new in studies of animal movement, we are only beginning to understand how the growth patterns of the cornified claw sheath may affect our ability to interpret the biogeochemical signals in these tissues. To move towards resolving this, we review the morphology of the epidermal cornified claw sheath in several taxa that illustrate substantial variation in growth patterns both between taxa and between individual distinct claw regions. For instance, in mammalian claws, deposition of keratinizing cells from the epidermis is nonlinear because the claw tip is composed of old and new cornified epidermal cells, whereas the cornified blade horn covering the claw's lateral walls is deposited continuously and without assortment, providing unbroken time-series data. We also consider patterns of growth in mammalian hooves, as well as reptilian, avian, and amphibian cornified claw sheaths, and address the need for expanded research in this field. We conclude this synthesis by describing a noninvasive technique for monitoring growth rates in a model mammal, the American badger {Taxidea taxus (Schreber, 1777)), and provide guidelines for future sampling of claw keratin, which will improve our ability to back-calculate the time of biogeochemical integration into this tissue. Nous faisons une revue du role des signatures biogeochimiques, telles que les isotopes stables et les elements en traces, dans le tissu corne des griffes comme moyens d'etudier les deplacements et le comportement alimentaire chez les vertebres, puisqu'il s'agit d'une methodologie non invasive qui peut retenir des signatures actuelles et passees. Puisque les techniques biogeochimiques sont d'usage relativement recent dans les etudes des deplacements animaux, nous commencons tout juste a comprendre comment les patrons de croissance de l'etui corne des griffes peuvent affecter notre capacite a interpreter les signaux biogeochimiques dans ces tissus. Pour faire du progres dans ce domaine, nous passons en revue la morphologie de l'etui corne epidermique de la griffe chez divers taxons, ce qui revele une importante variation dans les patrons de croissance, tant entre les taxons qu'entre les differentes regions distinctes de la griffe. Par exemple, dans les griffes de mammiferes, la deposition des cellules keratinisantes par l'epiderme ne se fait pas de facon lineaire parce que la pointe de la griffe est composee de cellules epidermiques cornees anciennes et recentes, alors que la lame cornee qui couvre les parois laterales de la griffe est deposee de maniere continue et sans assortiment, ce qui fournit une serie chronologique continue. Nous examinons aussi les patrons de croissance des sabots de mammiferes et des etuis cornes des griffes de reptiles, d'oiseaux et d'amphibiens. Nous terminons notre synthese en decrivant une technique non invasive pour suivre les taux de croissance chez un mammifere modele, le blaireau d'Amerique (Taxhka taxus (Schreber, 1777)), et fournissant des regles pour l'echantillonnage futur de la keratine des griffes, qui permettront d'ameliorer notre capacite de retrocalculer le moment de l'integration biogeochimique dans ce tissu. [Traduit par la Redaction], Introduction Understanding movement and foraging behaviour of animals on a daily, seasonal, or annual basis is fundamental to ecological, evolutionary, and conservation studies. Until recently, studying animal movement required trapping [...]