JournalTOCs

Avian Conservation and Ecology
Journal Prestige (SJR): 0.684

Citation Impact (citeScore): 2
Number of Followers: 16

This is an Open Access Journal

Open Access journal
ISSN (Print) 1712-6568
Published by Society of Canadian Ornithologists

[1 journal]

Natural history and community science records confirm rapid geographic
shifts in the distribution of Bachman’s Sparrow (Peucaea aestivalis)
since 1850
- Authors: Settlecowski, A. E; Davis, K. E. C, Cox, J. A, Woltmann, S, Taylor, S. S.
  Abstract: North American grassland birds colonized emerging habitat created by expanding agriculture in a pattern of eastward expansions from the mid-1800s to mid-1900s. These birds have been declining, since at least the mid-1900s, largely as result of anthropogenic landscape change. Only one bird that now breeds predominantly in southeastern pine savannas is thought to have experienced a concurrent range expansion into this region: Peucaea aestivalis (Bachman’s Sparrow). However, our understanding of the P. aestivalis expansion, and subsequent retraction to the southeastern United States, is largely based on a contemporaneous review of only a subset of historical records from beyond its modern, northern limit. We suggest an alternative explanation for these historical records is that P. aestivalis historically occurred more broadly than was recognized in contemporaneous literature. To evaluate these hypotheses, we reviewed field observations from literature, natural history collections, and eBird to show how P. aestivalis presence throughout eastern North America has shifted since the mid-1800s. To confirm that these findings were not the result of detection bias, we repeated our analysis on a common sparrow species (Spizella pusilla) with a largely overlapping breeding range, but no history of expansion and retraction. We confirm that P. aestivalis expanded its range, but add that prior to that expansion, its historical distribution was broader than commonly acknowledged today. As a result, we identify the northwestern historical limit of P. aestivalis, the Ouachita and Ozark highlands, as a potential source region for an eastward expansion that is consistent with those of other North American grassland birds of the era. We discuss the potential evolutionary and conservation implications of this range expansion on P. aestivalis given our more nuanced understanding of it. Anthropogenic landscape change initially provided additional habitat for P. aestivalis but has ultimately resulted in a reduction of the P. aestivalis distribution.
  PubDate: Mon, 09 May 2022 12:56:58 EDT
Food subsidies shape age structure in a top avian scavenger
- Authors: Fern?ndez-G?mez, L; Cort?s-Avizanda, A, Tiago, P, Byrne, F, Don?zar, J. Antonio
  Abstract: Human activities and recent changes in sanitary regulations are currently shaping the availability of carrion resources across ecosystems. How changes in regulations influence demographic parameters in avian scavengers is still poorly known. We combine photographic observations gathered by citizens and observational data from research projects in northern Spain to examine if the age structure of Eurasian Griffon Vulture (Gyps fulvus) populations at different trophic resources (natural randomly-distributed carcasses, predictable resources [supplementary feeding sites and farms], and landfills) varied in relation to modifications of sanitary regulations from 2004 onwards. We found that the proportion of immature birds increased significantly after the introduction of new European sanitary regulations allowing farmers to dispose of livestock carcasses in the field, rather than incinerating them. Also, we found that the age structure varied significantly between food resources, such that we detected a higher fraction of immatures at landfills, as well as in sites where carrion was highly clumped. These findings reveal that loss of natural randomness in carrion availability may elicit age-dependent effects on the spatial distribution of the vultures at the mesoscale which may ultimately affect population structure. Our findings shed light on challenges on how to manage food subsidies to preserve avian scavenger populations in an increasingly anthropized world.
  PubDate: Mon, 02 May 2022 11:02:20 EDT
Migratory songbirds and urban window collision mortality: vulnerability
depends on species, diel timing of migration, and age class
- Authors: Colling, O. M; Guglielmo, C. G, Bonner, S. J, Morbey, Y. E.
  Abstract: Hundreds of millions of birds are estimated to die annually in North America by colliding with windows, and understanding the species-level correlates of collision mortality is an important step towards mitigation. We used a 16-year window collision dataset for 35 migratory songbird species from Toronto's (Canada) Fatal Light Awareness Program (FLAP) to quantify species differences in vulnerability to urban window collision mortality and potential correlates during the autumn period by applying generalized linear models. To control for annual abundance, we used migration monitoring data from two stations. Our index of vulnerability was the catch ratio, defined as the ratio of annual catch-per-unit effort in each station's mist net program to annual catch-per-unit effort in FLAP. Catch ratios varied among species with Ovenbird (Seiurus aurocapilla), Common Yellowthroat (Geothlypis trichas), and Lincoln's Sparrow (Melospiza lincolnii) being most vulnerable to window collision mortality and Blue-headed Vireo (Vireo solitarius), Yellow-rumped Warbler (Setophaga coronata), and Ruby-crowned Kinglet (Regulus calendula) being least vulnerable. Foraging guild had a minor effect on the catch ratio, but species with a propensity for nocturnal migration had lower catch ratios (greater vulnerability) than those that did not. Based on a subset of species (n = 4) and years (n = 2), hatch-year birds were overrepresented relative to after-hatch-year birds in FLAP compared to the nearby migration monitoring station in 3 of 4 species. This study provides the first ranked list of species vulnerability to urban window collision mortality for songbirds migrating through downtown Toronto, provides evidence that juveniles are more vulnerable to window collision mortality than adults in some species, and highlights the need for more comparative studies of migratory movement behavior to investigate why some species are more vulnerable to urban window collision mortality than others.
  PubDate: Mon, 02 May 2022 10:10:46 EDT
In the still of the night: revisiting Eastern Whip-poor-will surveys with
passive acoustic monitoring
- Authors: Knight, E. C; Hannah, K. C, DeMoor, J.
  Abstract: Recent advances in passive acoustic monitoring warrant the review of survey protocols because passive acoustic monitoring can increase sampling effort with minimal additional cost. In particular, protocols for nocturnal species should be re-evaluated because automated processing with signal recognition is expected to perform well for these species and surveys conducted by human observers are often limited by safety concerns. We revisited the best survey practices for the Eastern Whip-poor-will (Antrostomus vociferus), a nocturnal species of conservation concern. Whip-poor-will surveys are typically limited to nighttime, but also to times of high lunar illumination because their calling rate is associated with moonlight levels. We used automated recognition to extract Whip-poor-will detections from a dataset of autonomous recording unit (ARU) recordings from sites with known Eastern Whip-poor-will occupancy in Ontario, Canada. Temperature and time relative to sunset had particularly strong quadratic effects on detectability, with detectability maximized at 13 'C and 4 hours after sunset. Moon altitude and day of year had positive effects on detectability, while wind speed had negative effects on detectability. We found constraining surveys by optimal values of those detectability covariates was worthwhile only up until 10 recordings, at which point the cumulative probability of detecting an Eastern Whip-poor-will at each site was equal between constrained and unconstrained nocturnal recordings. The number of recordings required to reach an asymptote for detectability was between 81 and 97, depending on recording length. We provide objective-specific recommendations for Eastern Whip-poor-will surveys and suggest unconstrained passive acoustic monitoring as the preferred survey method for many objectives. Given the rise of passive acoustic monitoring, survey practices for many species should be revisited because the increases in sampling effort provided by ARUs can improve cumulative detection probability and potentially outweigh the advantages of limiting surveys to times and dates of optimal detectability.
  PubDate: Mon, 11 Apr 2022 12:50:41 EDT
Understory structure and heterospecifics influence the occupancy of a
ground-nesting species of conservation concern, the Canada Warbler
- Authors: Dimmig, G. W; Rota, C, Wood, P, Lituma, C. M.
  Abstract: Forest structure and composition in eastern U.S. forests are changing because of forest regeneration after farmland abandonment, less frequent occurrence of severe disturbances, and climate change. Some of these changes may disproportionally affect birds that rely on gap dynamics or other forest canopy disturbances to create understory habitat. The Canada Warbler (Cardellina canadensis) is one such understory specialist that has undergone consistent declines. We assessed environmental and interspecific factors associated with Canada Warbler space use in its southern breeding distribution to understand potential causes of population declines and inform conservation efforts. We evaluated Canada Warbler occupancy from 840 point count surveys conducted in 2017 and 2018 at 470 unique locations (79% of locations surveyed in both years) throughout Monongahela National Forest, West Virginia, USA. We modeled Canada Warbler occupancy probability as a function of environmental variables and included Black-throated Blue Warbler (Setophaga caerulescens) and Hermit Thrush (Catharus guttatus) as interacting species because all three species exhibit similar habitat preferences. Canada Warblers were most likely to occur in areas with rhododendron (Rhododendron maximum) density> 0.27 stems/m² and within 3 m of riparian areas (streams and wetlands). They were also more likely to occur in mid-elevation (highest occupancy at 930 m) northern hardwood forests when Black-throated Blue Warblers were also present. Black-throated Blue Warblers were most likely to occupy mid-elevation sites with high shrub density, whereas Hermit Thrushes were more likely to occupy high-elevation, old-age forests. Potential management actions could focus on conserving riparian areas in northern hardwood forests, especially those with dense rhododendron thickets. Such potential actions could also be beneficial across the entire elevation range we explored within the region (500–1300 m). Canada Warblers may be benefiting from the recent spread of rhododendron habitats and northern hardwood forest types within West Virginia.
  PubDate: Mon, 11 Apr 2022 12:01:32 EDT
Pre-breeding foraging ecology of three tern species nesting in the Gulf of
Maine
- Authors: Bratton, R. M; Legett, H. D, Shannon, P, Yakola, K. C, Gerson, A. R, Staudinger, M. D.
  Abstract: A variety of seabird species migrate annually from wintering grounds in the Southern Hemisphere to the Gulf of Maine, USA to breed and raise their young. Post-migration, adult seabirds depend on the spatio-temporal match of reliable food resources to replenish energy reserves before breeding. However, the conditions during this critical window of time are becoming increasingly uncertain given the magnitude and pace at which climate change is impacting the Gulf of Maine region. We investigated the pre-breeding foraging ecology of Arctic Terns (Sterna paradisaea), Common Terns (S. hirundo), and the federally endangered Roseate Tern (S. dougallii) by analyzing stable carbon (δ13C) and nitrogen (δ15N) isotopes in eggshell tissues collected from seven islands in the Gulf of Maine from 2016 to 2018. Results show at the interspecific level, adult foraging patterns are consistent with expectations based on chick diets. At interisland and interannual scales, variation in isotopic values and niche breadths suggest foraging habits are highly localized. Although uncertainty remains, interannual trends also suggest warmer ocean conditions are either affecting tern foraging behaviors and/or prey resource availability during the late spring and early summer. Overall, results provide new information on adult tern foraging ecology in an important breeding area experiencing rapid environmental change.
  PubDate: Mon, 11 Apr 2022 10:31:01 EDT
Nest-site selection and breeding biology of the locally endangered
Micronesian Starling (Aplonis opaca) informs its recovery on Guam
- Authors: Savidge, J. A; Kastner, M, Pollock, H. S, Seibert, T. F.
  Abstract: Micronesian Starlings'(Aplonis opaca) are one of two native forest bird species that have survived on the island of Guam despite predation by invasive brown tree snakes (Boiga irregularis). We report the first detailed account'of the starling’s breeding biology to help understand how this species has persisted and guide management to conserve and expand the population. Our surveys indicated that although starlings continued to forage in nearby forest, nesting occurred almost exclusively in developed habitat on Andersen Air Force Base. We located 36 active nest sites in a variety of natural and artificial structures, many of which were likely difficult or impossible for snakes to access. We report reproductive data from those nest sites and also predator-resistant nestboxes (n = 48 pairs using 58 boxes) installed in our study area. Typical of tropical species, the average clutch was'small (2.19 ' 0.55 [SD] over 431 nesting attempts), but pairs nested repeatedly throughout the year.'Pairs showed high site fidelity, and nestboxes (n = 70) installed at least 34 m from forest edge were readily colonized with 77% occupied by the end of our study. Protected nestboxes in urbanized areas along with snake suppression may be useful strategies for expanding the population of Micronesian Starlings and consequently restoring seed dispersal in nearby forest on Guam.
  PubDate: Tue, 05 Apr 2022 08:45:30 EDT
Mortality of grassland birds increases with transmission lines
- Authors: Martin, C. J; Bork, E. W, Nielsen, S. E.
  Abstract: Electrical transmission line development has been expanding globally by 5% per year, leading to increases in avian collisions with lines. Canadian estimates of transmission line collision mortalities range from 2.5 to 25.6 million birds per year, with the majority of mortalities attributed to collisions with overhead shield wires, and by susceptible birds that are young, large-bodied, with low maneuverability, or in open habitats. In this study, avian mortality was estimated for a ~4900 ha area in the mixed-grass prairie of southeastern Alberta following construction of two major transmission lines. We surveyed seven 500 m transects 7–10 times during both the breeding and migration seasons, where transects were categorized into road (n = 2), transmission line (n = 2), wetland (with transmission lines above; n = 1), or control (n = 2) areas. During the 2016 breeding season (5 May–24 June), we detected 23 mortalities under transmission lines, 7 mortalities beside roads, and no mortalities in controls. In the 2017 spring migration season (31 March–5 May), we detected 24 mortalities under transmission lines, 3 mortalities beside roads, and no mortalities in controls. Mortality rates were adjusted with biases estimated from detectability and scavenging trials. Scavenging rates were high (82% of carcasses were scavenged within 5 days) and detectability of deceased birds was positively related to body size. Overall, linear disturbances within the study area, including 37.7 km of highways and transmission lines, contributed to an estimated 75 deaths/km of linear disturbance during one migration and one breeding season (~50 deaths/km of transmission line and ~25 deaths/km of road; ~1904 bird mortalities total). These findings point to the need for mitigation to reduce bird mortality, thereby minimizing the long-term impact of linear disturbances, such as transmission lines and roads, on associated bird communities.
  PubDate: Mon, 04 Apr 2022 10:03:49 EDT
A lidar-based openness index to aid conservation planning for grassland
wildlife
- Authors: Allen, M. C; Almendinger, T, Barreca, C. T, Lockwood, J. L.
  Abstract: Visual openness is a key element in habitat selection for many animals of grasslands and other open habitats, especially birds. Obstructions to visual openness in the form of human infrastructure or inopportune woody vegetation growth can lead to habitat avoidance, and thus pose conservation challenges. Here we introduce a remotely sensed, lidar-based index of visual openness. Like previous indices of visual openness, ours is based on the vertical angle to the horizon; however, its calculation from remotely sensed data allows it to be easily mapped across the landscape. We illustrate its potential usage by calculating the index multiple ways within two large fields in central New Jersey, USA, and evaluating the effects of openness on habitat use by a grassland bird, the Grasshopper Sparrow (Ammodramus savannarum), within an occupancy modeling framework. We used the best performing model and digitally edited openness maps to project population responses under five hypothetical management scenarios of increased habitat openness. Occupancy modeling revealed that a version of the index calculated based on the maximum angle to the horizon best explained Grasshopper Sparrow occupancy patterns. Models also revealed that Grasshopper Sparrows showed a negative response to openness reductions caused by both powerlines and trees. Predictions based on the increased openness scenarios indicated that removal of tree lines and powerlines could increase patch-level occupancy of the sparrows in the affected fields by up to 15% and 9%, respectively. Where adequate data exist, this index has the potential to facilitate the study of openness-habitat use relationships in a variety of open-dwelling fauna and in a variety of habitats, from tundra to marshes to grasslands. Notably, it has promising potential for use in modeling habitat suitability and projecting potential impacts in response to anthropogenic changes in visual openness, such as wind farms, power infrastructure, or vegetation management.
  PubDate: Mon, 04 Apr 2022 08:59:51 EDT
Migratory stopover sites used by Reddish Egrets: prioritization for
conservation
- Authors: Koczur, L. M; Ballard, B. M.
  Abstract: The conditions encountered during the migratory period, particularly at stopover sites, can influence individual survival, reproductive success, and population stability; therefore, knowledge of migration ecology is important for developing conservation strategies. We monitored stopover site use by Reddish Egrets (Egretta rufescens) marked with satellite transmitters between their breeding area in southern Texas, USA, and wintering sites in Mexico and El Salvador. The duration of time spent at stopover sites varied among individuals and seasons, ranging from 1 to 64 days at a particular site. Three of the four individuals that were tracked for multiple seasons flew farther between stopover sites during autumn migration compared to spring, and the average distance between stopovers ranged from 192 to 580 km among individuals. Laguna San Andres in Tamaulipas, Mexico, appeared to be the most important stopover site based on the proportion of the marked population that used it. Understanding the stopover ecology and habitat use of migratory individuals will help direct conservation efforts for the species.
  PubDate: Mon, 21 Mar 2022 14:16:36 EDT
Understanding widespread declines for Common Terns across inland North
America: productivity estimates, causes of reproductive failure, and
movement of Common Terns breeding in the large lakes of Manitoba
- Authors: Arnold, J. M; Oswald, S. A, Wilson, S, Szczys, P.
  Abstract: Common Tern (Sterna hirundo) breeding populations in inland North America have declined significantly since the 1970s. A 2012 survey of the large Manitoba lakes, previously the largest known inland population stronghold, reported a 57–67% decline in 20 years. A further 38% decline by 2017 highlights the urgent need for research and management. We use ground-based estimates of productivity and analysis of microsatellite markers to provide the first detailed insight into breeding status and movements of Common Terns in this region. At six breeding colonies in 2012, we recorded breeding success in fenced plots, counted fledglings, documented predators and floods, and collected blood samples for microsatellite analysis of movement. Productivity ranged from 0.0 to 2.0 chicks fledged per nest, being highest at large colonies (> 1000 nests) located far away from human settlements (20–30 km). Large-scale breeding failure from predation occurred at smaller colonies close to human settlement. The most common predators were Black-crowned Night Herons (Nycticorax nycticorax) and Great Horned Owls (Bubo virginianus), but we also report three novel predators: Bald Eagles (Haliaeetus leucocephalus), gray wolves (Canis lupus), and river otters (Lontra canadensis). Microsatellite analysis suggested little eastward emigration, but instead a 100-fold increase in immigration from the Great Lakes between the 1990s and 2010s. Substantial population declines in the Manitoba Lakes despite this influx imply that net losses are occurring within inland-breeding populations. Terns now appear to switch frequently between breeding colonies in the region, possibly in response to predation and/or flooding. Although some colonies achieved productivity during the one-year study, continued population decline indicates that monitoring and studies of adult survival and movement are needed, especially given the on-going environmental changes within the region. Only by coupling these data with further efforts in unsurveyed boreal regions can the status of inland-breeding Common Terns be determined and strategies developed to curb apparent, large-scale population declines.
  PubDate: Mon, 21 Mar 2022 13:50:40 EDT
Post-fledging survival, movements, and habitat associations of Gray Vireos
in New Mexico
- Authors: Fischer, S. E; Granillo, K, Streby, H. M.
  Abstract: Annual population growth in songbirds can be particularly sensitive to post-fledging survival, but research and management are frequently biased toward the nesting stage. Post-fledging information is particularly scarce for species breeding in desert bird communities, many of which have collapsed in recent decades. During 2017–2019 at Sevilleta National Wildlife Refuge, New Mexico, USA, we used radio telemetry to monitor survival, movements, and habitat associations of 90 fledgling Gray Vireos (Vireo vicinior), a desert-dwelling species of conservation concern. We used logistic exposure models to investigate the relationship between fledgling survival and habitat features at two spatial scales. Overall, we estimated that 51 ± 8% of fledglings survived the monitoring period. All mortalities occurred during the first 12 days post-fledging and were attributed to predation and environmental exposure. In daily survival models focused on predation mortalities, age was the strongest predictor of survival. Daily survival rate was not related to any habitat variables we measured. Percent tree cover used by birds during the first 12 days post-fledging was similar to that of nesting sites and greater than that of random locations. Similarly, fledglings occupied individual trees and shrubs with lateral vegetation cover similar to that of nest locations. Minimum daily distance traveled, distance from nests, and variance associated with these measures, all increased with age. Except for the use of a larger area, habitats used by Gray Vireos during the post-fledging period were similar to those used for nesting in our study population, indicating that maintenance of large patches of moderately dense juniper is desirable for this species. More study is needed from populations in less pristine and more heterogeneous landscapes. More broadly, given the importance of first-year survival in demographic models and the declines of dryland birds, information is needed on the post-fledging period of many desert songbirds.
  PubDate: Mon, 21 Mar 2022 09:42:47 EDT
Spatially explicit population trend estimates of owls in the Maritime
provinces of Canada and the influence of call playback
- Authors: Ethier, D. M; Torrenta, R, Kouwenberg, A.
  Abstract: Documenting and interpreting trends in the abundance and distribution of bird populations is critical to monitoring their status and setting conservation priorities. This process requires standardized monitoring and robust analytical techniques, which can resolve trends at spatial scales of management interest while disentangling the influence that various data collection protocols can have on the interpretation of results. We used a 19-year citizen-science-collected dataset (2001–2019), the Nocturnal Owl Survey, to assess abundance trends in Barred Owl (Strix varia), Northern Saw-whet Owl (Aegolius acadicus), and Great Horned Owl (Bubo virginianus) at both fine and broad-scales. To achieve this, we used a spatially explicit modeling approach that facilitates the borrowing of information across spatial boundaries, allowing for more robust trend estimates at finer spatial scales. Further, we assessed the potential influence of the call-playback protocol on trend estimates. At fine spatial scales, we found that a data collection protocol that includes call playbacks provided more precise results to assess relative changes in abundance (i.e., reduced uncertainty). At broader spatial scales, trend estimates were unaffected by data collection methodology (i.e., silent listening versus call playback). Specifically, at the scale of the region or province, we found that populations of focal owl species in the Maritimes of Canada have remained stable over the past 19 years. However, at finer scales, trends are more variable and may create opportunities to test alternative hypotheses about drivers of population change and the effects of management actions at scales amenable to conservation action. The statistical analyses are anticipated to form a national, publicly accessible framework for status assessments of owls in Canada and will provide resource managers and researchers a base from which to evaluate the influence of land management and conservation practices on owl populations across the nation.
  PubDate: Sat, 19 Mar 2022 16:08:40 EDT
Forest specialist species in the urban landscape: Do different levels of
urbanization affect the movements of Forest Red-tailed Black Cockatoos
(Calyptorhynchus banksii naso)'
- Authors: Rycken, S. J. E; Warren, K. S, Yeap, L, Donaldson, R, Mawson, P, Dawson, R, Shephard, J. M.
  Abstract: Anthropogenic landscape modification which leads to the displacement of species, is arguably one of the most profound impacts on animal movement globally. In urban landscapes, animal movement is generally impacted by varying levels of increased urbanization. However, this is species dependent and is mostly guided by the surrounding habitat. Fragmentation and habitat patch isolation must be considered at scales appropriate to the study species. Using telemetry, we test these assumptions investigating movement patterns of flocks of Forest Red-tailed Black Cockatoos (Calyptorhynchus banksii naso; RTBC) between three regions: urban, peri-urban, and forest using GPS and satellite PTT. This species occurs at varying levels of urbanization, however, how this might affect its movements is largely unknown. We did not find evidence that RTBC movement was impaired in the urban region compared with peri-urban or forest regions. It found, however, a significant within-region variation in movement extent among flocks and across regions depending on foraging resource availability and location. Differences in daily movement distance (Av. 4.96 - 16.41 km) and home range size (6.02 - 52.57 km2) between urban flocks appeared to be associated with the proximity of green spaces as roosts and foraging sites, with roadside vegetation providing important foraging resources and movement corridors. Key urban habitats were predominantly located in public nature reserves and private properties, with roadside vegetation connecting these sites for RTBC. The findings of this study highlight that conservation management for this and many other threatened species should regard the urban landscape as a critical habitat for urban adapted species. This would include management of its green spaces with connectivity and offsets from roads in mind. Furthermore, future research should focus on identifying additional key habitat sites (resource selection) and species distribution modeling, which will facilitate an active and adaptive approach towards this species' conservation management.
  PubDate: Thu, 17 Mar 2022 10:34:03 EDT
Soil management of olive groves has contrasting effects on nest densities
and reproductive success of tree-nesting passerines
- Authors: Castro-Caro, J; Barrio, I. C, S?nchez Tortosa, F.
  Abstract: Agri-environmental measures aim at mitigating the negative impacts of modern agriculture on farmland biodiversity. For example, soil management practices can positively influence the abundance and diversity of songbirds in olive groves by enhancing habitat and food availability. However, little is known about their potential implications on the breeding success of these species.We monitored nest density and breeding performance of tree-nesting birds in 17 olive groves of southern Spain under two contrasting soil management regimes (with and without herbaceous cover) over three years. We analyzed breeding success by examining the transitions between different stages of the breeding cycle for three common cardueline finches: Common Linnet (Linaria cannabina), European Greenfinch (Chloris chloris), and European Serin (Serinus serinus). Breeding success of songbirds was low (19% of 88 nests for L. cannabina, 16% of 196 nests for C. chloris, and 38% of 234 nests for S. serinus). Many nests were abandoned prior to egg laying and nesting failure was highest between egg laying and hatching. Nest predation (56.6%) was the main cause of nest loss. Although soil management regimes did not influence breeding success, the presence of herbaceous cover had opposing effects on nest densities of the three species: groves with herbaceous cover had higher nest densities for greenfinches, lower for serins, and this treatment had no effect on Common Linnet. Other factors, like disturbances due to management activities or interannual weather variation may have a larger impact on nesting success than soil management regimes, at least for some species and for specific stages of their breeding cycle. The fact that nest densities of some birds were negatively affected by soil treatments associated with agri-environmental actions aimed at benefiting biodiversity raises the question of the general applicability of these measures for conservation.
  PubDate: Wed, 16 Mar 2022 06:46:01 EDT
Female migration phenology and climate conditions explain juvenile Red
Knot (Calidris canutus rufa) counts during fall migration
- Authors: McKinnon, L; Schmaltz, L, Aubry, Y, Rochepault, Y, Buidin, C, Juillet, C.
  Abstract: The management of avian populations at risk requires accurate estimates of vital rates across age and sex classes to effectively identify the most vulnerable demographic and support conservation actions. In the endangered Red Knot (Calidris canutus rufa), there are relatively few reliable estimates of reproductive success because they breed in such low densities across such a large and relatively inaccessible area in Arctic Canada. The purpose of this study is to test whether a migratory time lag between adult male and female knots during post-breeding southbound migration could be a reliable index of reproductive success for this species. If so, we expected to find a positive relationship between a time lag in male migration and the number or proportion of juveniles present at the same fall migration site. To test this hypothesis, we analyzed 13 years of capture-mark-recapture and census data from an important staging area during southbound migration. We found a strong and consistent age and sex-specific chronology; median passage dates for females were approximately 2 weeks earlier than males, with juveniles following 1 month later than adults of both sexes. For most years, there was a significant time lag of up to 27 days between females and males. However, we found no evidence to support that this time lag explained variation in the number of juveniles at the stopover site each year. Instead, we found that the timing of female migration along with an index of environmental conditions on the breeding grounds and during migration best described the proportion of juveniles present during migration. Overall, our results cast doubt on the reliability of the male migratory time lag as an indicator of breeding success.
  PubDate: Wed, 02 Mar 2022 12:32:51 EST
Abundance and habitat use estimates show Lesser Yellowlegs (Tringa
flavipes) breed in high numbers in interior Alaska
- Authors: Martin, E. C; Doherty, Jr, P. F, Jochum, K. A, Bagley, C. F.
  Abstract: Lesser Yellowlegs (Tringa flavipes) abundance has declined by approximately 75% across North America since 1970. Despite this dramatic decline, Lesser Yellowlegs are infrequently studied on their breeding grounds and have rarely been studied in the boreal forest of Alaska where population size is uncertain. We used a spatially balanced sampling design and surveyed 400 by 400 m plots in 2016 and 2017 to (1) estimate abundance and habitat use of Lesser Yellowlegs breeding on military lands in interior Alaska, and (2) test hypotheses about which habitat covariates best explain variation in plot abundances and habitat use. We predicted that boreal forest habitats on military lands in central Alaska supported a large percent of breeding Lesser Yellowlegs and that plots containing water and situated closer to wetlands would have the highest abundances compared to other habitat variables tested. We also predicted that increased presence of lowland habitat and associated vegetation covariates (e.g., percent low scrub canopy) increased probability of habitat use. In 2017, Lesser Yellowlegs abundance at the study site was 12,478 individuals, and habitat use was negatively associated with increasing elevation and percent canopy cover on plot. We estimate that military lands in interior Alaska support 8% of all Lesser Yellowlegs breeding in Alaska. Therefore, studies identifying important Lesser Yellowlegs breeding habitat and addressing conservation priorities in the boreal forest should be continued.
  PubDate: Tue, 01 Mar 2022 14:59:46 EST
The nuthatch and the hare: Slow explorers dominate in a re-established
- Authors: Gray, M; Sieving, K. E, Cox, J. A.
  Abstract: Animal behavior regularly has substantial effects on the outcomes of reintroduction efforts.Reintroduction involves capturing a subset of individuals from a source population and releasingthem into novel environments where variation in retention rates, predation, and territoryacquisition could affect the age-class structure, sex ratio, and genetic and phenotypiccharacteristics of restored populations. Exploratory behavior, quantified as the rate thatindividuals explore novel settings, is one such heritable trait that might be affected bytranslocation, especially given recent studies suggesting that exploratory behavior can predict thesurvival and retention of individuals in unfamiliar environments. To assess the potential effectsthat translocation may have on exploratory behavior, we compared exploratory behavior for threeBrown-headed Nuthatch (Sitta pusilla) populations: (1) a population reintroduced to EvergladesNational Park in 1998; (2) a population close to the original source population, and (3) a distantcontrol population in north Florida. Exploratory behavior was quantified by placing individuals(n=17 per population) in an exploratory chamber and comparing flights/hops, scanning events,thoroughness of exploration, and other movement behaviors. We found that individuals in thereintroduced population scanned less, conducted fewer flights/hops, and were more sedentary thanindividuals in the other populations. Our findings suggest a shift in the prevalence of personalitytypes toward slow explorers has taken place in the 20 years since reintroduction, adding to otherstudies suggesting that slow explorers fare better in novel environments. Although the reintroducedpopulation contained fewer fast-exploring individuals relative to the other populations studied,fast-explorer phenotypes may increase over time if they convey the fitness benefits described in other studies.
  PubDate: Tue, 01 Mar 2022 10:46:27 EST
The invasive parasitic fly Philornis downsi is threatening Little
Vermilion Flycatchers on the Galápagos Islands
- Authors: Mosquera, D; Fessl, B, Anchundia, D, Heyer, E, Leuba, C, Nemeth, E, Rojas, M. Lorena, Sevilla, C, Tebbich, S.
  Abstract: Populations of several species of birds endemic to the Galápagos Islands have declined during recent decades, including endemic Little Vermilion Flycatchers (Pyrocephalus nanus). Understanding the reasons for the low breeding success of this species is a prerequisite for developing efficient conservation strategies. Studies of sympatric Darwin’s finches suggest two potential reasons: parasitism by the invasive parasitic fly Philornis downsi and extreme climatic events. We investigated the role of each in the breeding success of Little Vermilion Flycatchers during three breeding seasons in the agricultural zone of Isabela Island. We found that Little Vermilion Flycatchers were severely affected by P. downsi, depending on the time of breeding. Nest success was high early in the breeding season (60% were successful) when rates of P. downsi prevalence and intensity were low, but nest success was zero and all nests were infested later in the breeding season. Philornis downsi prevalence and intensity increased with increasing temperature. Both low and high levels of rainfall had a negative effect on nest survival. A parasite removal experiment using insecticide confirmed the detrimental effect of the invasive parasite; nests infested with P. downsi had significantly lower nest success than treated nests. Injection of insecticide into nest bases can be an efficient short-term way to increase the nesting success of Little Vermilion Flycatchers, but finding long-term measures to control the P. downsi population is of utmost importance.
  PubDate: Tue, 01 Mar 2022 09:38:13 EST
Canada Goose populations harvested in Eastern James Bay by Eeyou Istchee
Cree hunters
- Authors: Giroux, J; Rodrigue, J, Brook, R. W, Patenaude-Monette, M.
  Abstract: Canada Geese (Branta canadensis) are an important wildlife food resource for Cree people living in communities along the James Bay coasts. According to Traditional Ecological Knowledge, environmental changes along the coast have affected hunting success. Also, changes in the relative abundance of different goose populations that use James Bay may affect hunting opportunities. The objective of our study was to use band recoveries to identify Canada Goose populations harvested by Eeyou Istchee Cree hunters in their Eastern James Bay territory between 2000 and 2020. A total of 744 band recoveries were reported including 198 from the Atlantic Population (AP), 82 from the Southern Hudson Bay Population (SHBP), 122 from the Atlantic Flyway Resident Population (AFRP), 339 from the Mississippi Flyway Giant Population (MFGP), and three that could not be assigned to a population. The percentage of banded geese that were recovered was three times greater for the AP than for the other three populations. Eighty-seven percent of recoveries were reported in spring and 72% were submitted by hunters from the two northern communities (Chisasibi and Wemindji). Most recoveries were reported from coastal hunting sites, but a greater proportion of banded geese of the AP were recovered inland compared to the other goose populations, an indication of their propensity to migrate inland. The most noticeable change in the goose harvest compared to the 1970s was the rapid increase of molt migrant temperate-breeding geese of the AFRP and MFGP. In addition to environmental changes along the James Bay east coast, changes in the relative abundance of each goose population may affect hunting success because each population is differently susceptible to hunting within the territory due to differences in migratory behavior. Our study demonstrates the usefulness of band recoveries in tracking these changes and we therefore encourage agencies to maintain banding programs and Cree hunters to report their recovered bands.
  PubDate: Thu, 24 Feb 2022 09:06:28 EST