Search

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]

Establishing links between breeding, stopover, and wintering sites for migratory species is important for their effective conservation and management. Isotopic assignment methods used to create these connections rely on the use of predictable, established relationships between the isotopic composition of environmental hydrogen and that of the non-exchangeable hydrogen in animal tissues, often in the form of a calibration equation relating feather (δ2Hf) values derived from known-origin individuals and amount-weighted long-term precipitation (δ2Hp) data. The efficacy of assigning waterfowl to moult origin using stable isotopes depends on the accuracy of these relationships and their statistical uncertainty. Most current calibrations for terrestrial species in North America are done using amount-weighted mean growing-season δ2Hp values, but the calibration relationship is less clear for aquatic and semi-aquatic species. Our objective was to critically evaluate current methods used to calibrate δ2Hp isoscapes to predicted δ2Hf values for waterfowl. Specifically, we evaluated the strength of the relationships between δ2Hp values from three commonly used isoscapes and known-origin δ2Hf values three published datasets and one collected as part of this study, also grouping these data into foraging guilds (dabbling vs diving ducks). We then evaluated the performance of assignments using these calibrations by applying a cross-validation procedure. It remains unclear if any of the tested δ2Hp isoscapes better predict surface water inputs into food webs for foraging waterfowl. We found only marginal differences in the performance of the tested known-origin datasets, where the combined foraging-guild-specific datasets showed lower assignment precision and model fit compared to data for individual species. We recommend the use of the more conservative combined foraging-guild-specific datasets to assign geographic origin for all dabbling duck species. Refining these relationships is important for improved waterfowl management and contributes to a better understanding of the limitations of assignment methods when using the isotope approach. [ABSTRACT FROM AUTHOR]

Copyright of Avian Conservation & Ecology is the property of Resilience Alliance 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.)

Waterfowl management is more effective when based on detailed information on population connectivity between breeding, wintering, and stopover sites. For the American black duck (Anas rubripes), a species of conservation concern, estimates for the fall age ratio at harvest differed depending on whether harvest data were derived from Canada or the United States, suggesting regional differences. Within Canada, hunters in Atlantic Canada were more likely to harvest black ducks from nearby breeding locations compared to hunters in southern Ontario and Quebec, Canada, who were more likely to harvest individuals from the Boreal Softwood and Taiga Shield of eastern Canada. Black ducks harvested in the United States are thought to originate predominantly from northern portions of the breeding range, leading to the flyover hypothesis, which postulates that black ducks produced in the Boreal Softwood and Taiga Shield region are less susceptible to harvest by hunters in Atlantic Canada and northeastern United States. To test the flyover hypothesis, we examined regional and temporal differences in the origins of harvested black ducks using feathers from wings (n = 664) submitted by hunters to the species composition and parts collection surveys across 3 hunting seasons (2017–2018, 2018–2019, 2019–2020). We used a likelihood‐based assignment method that relied on feather stable‐hydrogen isotopes (δ2H) and stable‐carbon isotopes (δ13C) to determine the natal or molt origin of individuals harvested within eastern Canada and the United States. We also used a spatial clustering technique to group harvested individuals by area of origin without a priori knowledge of such regions. Adult female black ducks originated farther south compared to males and juveniles. All sexes and ages of black ducks harvested in Atlantic Canada showed predominantly southern origins, while those harvested in the United States and other Canadian provinces primarily originated farther north within the boreal, supporting the flyover hypothesis. By contrast, we found no relationship between timing of harvest or peaks of migration and individual origin. After combining band returns and stable isotopes, we inferred 2 distinct stocks: the Mississippi flyway stock and the Atlantic flyway stock. We recommend that regional demographic parameters, particularly for Atlantic Canada, be directly measured to promote more effective conservation of black ducks and optimize harvest opportunities in the United States and Canada. [ABSTRACT FROM AUTHOR]

Mature aspen (genus Populus L..) and maple (genus Acer L.) forests appear to be high-quality breeding habitat for Yellow-bellied Sapsuckers (Sphyrapicus varius (L., 1766)). To explore some of the mechanisms that influence quality of the breeding habitat, we measured demographic and breeding resources in four forest stands each of 95-year-old quaking aspen (Populus tremuloides Michx.) and 182-year-old sugar maple (Acer saccharum Marsh.) in Algonquin Provincial Park, Ontario, from 2007 to 2009. Population density was higher, egg laying earlier, clutches larger, hatching success greater, and per capita and population fledgling production higher in maple stands compared with aspen stands. Longer nest-building and prelaying stages in aspen stands delayed egg laying by 5 days relative to maple stands. The delay in egg laying in aspen stands may have been caused by lower quality sap resources, which then resulted in lower productivity. Adults delivered smaller food loads to nests in aspen stands than in maple stands, which may have increased nestling mortality in aspen stands. Although per capita fledgling production was lower in aspen stands than in maple stands, Yellow-bellied Sapsuckers in both forests were able to replace themselves, suggesting that mature deciduous and mixed-deciduous forests, in general, are high-quality breeding habitat for this sapsucker. Les forets matures de peupliers (le genre Populus L.) et d'erables (le genre Acer L.) semblent fournir un habitat de reproduction de haute qualite au pic macule; (Sphyrapicus varius (L., 1766)). Avec comme objectif d'explorer certains des mecanismes qui influencent la qualite de l'habitat de reproduction, nous avons mesure les ressources demographiques et reproductives dans quatre peuplements forestiers de peupliers faux-trembles (Populus tremuloides Michx.) de 95 ans et durables a sucre (Acer saccharum Marsh.) de 182 ans dans le Parc provincial Algonquin, Ontario, de 2007 a 2009. La densite de population est plus eleveie, la ponte plus hative, les couveees plus grandes, le succes de l'eclosion plus eelevee et la production de petits a l'envol plus importante dans l'ensemble de la population et par individu dans les peuplements d'erables que dans ceux de peupliers. La duree plus longue des etapes de la construction du nid et d'avant la ponte dans les peuplements de peupliers retarde la ponte de 5 jours par rapport aux peuplements d'erables. Ce deelai de la ponte dans les peuplements de peupliers peut etre dfl aux ressources de seve de moins bonne qualite;, ce qui mene a une productivite reduite. Les adultes des peuplements de peupliers rapportent au nid des charges alimentaires plus petites que ceux des peuplements d'erables, ce qui peut augmenter la mortalitee des petits au nid dans les peuplements de peupliers. Bien que la production de petits a l'envol par individu soit plus faible dans les peuplements de peupliers que dans ceux d'erables, les pics maculeis des deux forets sont capables d'assurer leur remplacement, ce qui laisse croire qu'en geneeral les forets matures de;cidues et mixtes-de;cidues repre;sentent des habitats de reproduction de haute qualite; pour ce pic. [Traduit par la Redaction], Introduction Aspen (genus Populus L.) forests are generally associated with disturbance events (e.g., fire, wind throw), whereas maple (genus Acer L.) forests are usually considered the endpoint of succession (Begon [...]

Active water management of wetlands promotes seed and tuber production to feed migrating waterfowl, but few assessments exist to determine how management actions influence wetland structure, vegetation and bird response throughout the year. We identified effects of full water drawdown, partial water drawdown and passive wetlands (no active dewatering during the growing season) on plant communities and bird abundance in wetlands of the Montezuma Wetlands Complex, New York, May–October 2016–2018 and February–April 2017–2019. We detected few differences in the plant community during June, but during September we detected greater vegetative forage quality index for waterfowl, annual plant cover and seed density in full and partial drawdowns than passive wetlands. Bird abundance was greater in June–July in passive wetlands and greater in September–October in full drawdowns. During spring migration, duck densities were greater in full and partial drawdowns. Our results indicate that wetland managers should use a mix of full drawdowns and passive wetlands to provide habitat for the greatest diversity and number of birds throughout the year. [ABSTRACT FROM AUTHOR]

We observed an adult Gray Jay (Perisoreus canadensis) that had captured an adult Black-capped Chickadee (Poecile atricapillus) in Algonquin Provincial Park, Ontario, Canada, during winter. Aerial pursuit of small, adult birds and an instance of capture and predation of a juvenile bird by a Gray Jay have been reported previously. Here, we present the first documented case of capture of a seemingly uninjured, adult bird. Received 22 March 2004, accepted 12 October 2004., The Gray Jay (Perisoreus canadensis) is well known for its diverse diet. Foods cited in the literature include arthropods, berries, carrion, nestling birds, fungi (Strickland and Ouellet 1993); a blood-stained [...]

The non-native invasive form of common reed (Phragmites australis australis; hereafter "invasive Phragmites") negatively affects certain flora and fauna throughout North America. As a result, much effort is spent in some locations controlling invasive Phragmites, although few estimates of the expected benefits of these efforts are available. We used data from Bird Studies Canada's Great Lakes Marsh Monitoring Program and Central Michigan University's Great Lakes Coastal Wetland Monitoring Program to estimate changes in 1) species richness, 2) total abundance, and 3) occurrence of 9 breeding marsh bird species and 8 breeding marsh frog species before and after control of invasive Phragmites. Our study took place between 2011 and 2018 throughout 3 Great Lakes coastal wetland complexes located on Lake Huron and Lake Erie in southern Ontario. We found at sample sites where invasive Phragmites was controlled that species richness of 5 breeding marsh bitterns (e.g., Botaurus sp.) and rails (e.g., Rallus sp.) of conservation concern increased by 1.1 species, and that total abundance of these species combined increased by 1.8 individuals. By contrast, we observed no change in these responses at nearby sample sites where no Phragmites control occurred. We found no change in occurrence of any frog species or species richness or crude calling frequency of all frog species combined in relation to control of Phragmites, although we lacked the ability to detect subtle changes in abundance of frogs, so more information would be helpful before firm conclusions can be made in relation to frogs and control of invasive Phragmites in our study system. Our study shows that control of invasive Phragmites has a significant positive effect on breeding marsh bird species of conservation concern and suggests that continued effort to restore habitat for these species is warranted, particularly in areas where former breeding marsh bird biodiversity was high. [ABSTRACT FROM AUTHOR]