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Nathan R. Senner

Publications and source records attributed to Nathan R. Senner.

At least 19 recordsLinked to original sources
USGS2026

The cost of limited nocturnal roost availability on pre-migratory energy budgets in a central-place foraging shorebird, Numenius hudsonicus (Hudsonian Whimbrel)

Mobile species often travel long distances between the sites they use for different behaviors, such as central-place foragers that make daily commutes between a central roost and foraging sites. For migratory shorebird species that use coastal habitats, the limited availability of suitable nocturnal roost sites can lead individuals to commute long distances to their foraging territories, forcing them to balance the energetic cost of commuting with the need to refuel in between migratory flights. We investigated this potential trade-off in a population of Numenius hudsonicus (Hudsonian Whimbrel) that show wide variation in commute distance between a shared central nocturnal roost and individual foraging territories in coastal South Carolina, USA. We combined high-resolution movement data, behavioral state modeling, and empirical foraging behavior data to assess how increasing commute distances from a central nocturnal roost affect individual daily activity budgets, foraging habitat use, potential net energy gain, and breeding ground departure date. We found that N. hudsonicus that commute farther from their nocturnal roost spend a higher proportion of each day foraging and commuting, and that they delay their departure to the breeding grounds by 3–6 days. Our results indicate that roosting habitat close to foraging areas can reduce the energetic cost of commuting to help shorebirds avoid delays in migratory timing. Thus, protecting, restoring, and creating nocturnal roosting habitat close to foraging areas may enhance successful shorebird migration.

South Carolina↗
USGS2026

Tringa flavipes (Lesser Yellowlegs) from separate breeding sites subdivides the Prairie Pothole Region in space and time during southbound migration

Some staging regions support multiple groups of the same migratory species, each of which may use the region differently. Characterizing the ways, in which separate groups use such regions can therefore help to identify vulnerabilities during this sensitive period of the annual cycle. The Prairie Pothole Region (PPR) is a massive wetland complex in the northern Great Plains of North America used by ∼11 million shorebirds during migration. The PPR has been heavily modified by agriculture and is experiencing varied effects of global climate change, threatening the health of the shorebirds that rely on it. Here, we used 6 seasons of southbound tracking data of Tringa flavipes (Lesser Yellowlegs)—a long-distance migratory shorebird species with an estimated population decline of 63% over the last 4 decades—from 9 sites across their breeding range to explore differences in migratory behavior within this important staging region. We found that 75% of tracked individuals used the region during southbound migration, and T. flavipes from different breeding sites detoured 110–875 km from their most direct migratory route to access the PPR. Individuals that arrived later stayed longer and made more stops within the region than those that arrived early. Individuals originating from different breeding sites also displayed spatial and temporal segregation within the region: T. flavipes from southwest and central Alaska relied heavily on the northwestern PPR, while those from Canada used the central and southeastern portions of the PPR. Finally, timing of use varied among groups, but the southeastern PPR became increasingly important over the course of the southbound migratory window, as other wetlands likely dried out. Our study highlights the portions of the PPR of critical importance to migrating T. flavipes and the diversity of ways, in which different groups from within the same species can use a single staging region.

Alaska, Manitoba, Northwest Territories, Ontario, ↗
USGS2026

Nest site and habitat changes over 15 years in a predicted climate refugium in Beluga, AK, USA, have a positive impact on Hudsonian godwit (Limosa haemastica) nest survival

Climate change is transforming the Arctic and sub-Arctic at a pace that threatens many taxa with population declines and extinction. However, some habitats–such as muskeg bogs–can serve as climatic refugia and lessen the effects of a changing climate on the species that rely on them. Hudsonian Godwits ( Limosa haemastica ) are a species of migratory shorebird that utilizes the muskeg bogs of Alaska and Canada to breed. Our study focused on a muskeg bog in Beluga, Alaska, USA to see if it had changed from 2009 to 2023, if the availability of Godwit nests sites in the bogs changed in concert, and if Godwit nest survival was affected by any of these changes. We found that, overall, the bog dried and became more vegetated, with the proportional cover of graminoids, shrubs, and forbs all increasing during our study. Godwit nest sites also changed, with the proportion of shrubs and graminoids around nests increasing over time. Nonetheless, these changes did not negatively impact Godwit nest survival. Instead, nest survival increased ~ 22% during our study period, and we observed no decline in the number of potential nests sites available to Godwits. Taken together, these results suggest that while muskeg bogs are changing, they are also currently acting as climate refugia for Godwits. However, it is unclear for how long muskeg bogs can continue to buffer Godwits and other species from the effects of climate change.

Alaska↗
USGS2026

Growth, movement, and survival of precocial shorebird chicks are constrained by their environment.

Young animals are often less mobile than adults, while also having high energetic demands. They may therefore be more vulnerable to local-scale changes in environmental conditions. In particular, when 1 sex must grow more rapidly than the other to achieve a larger adult size, that sex may experience especially dramatic reductions in growth and survival in the face of suboptimal environmental conditions. In order to investigate the flexibility of individuals in response to local-scale environmental variation during development, we studied the sex-specific growth, movement, and survival of Hudsonian Godwit ( Limosa haemastica ) chicks—a sexually dimorphic, precocial shorebird that breeds in the sub-Arctic and exhibits a male-skewed adult sex ratio. We found that female chicks—which must grow to a larger adult size—reached their maximum growth rates at a later age, but had similar growth rates to males before that and survived equally well to 21 days. We also found that, irrespective of sex, chicks had reduced movement rates when they were young and/or temperatures were cold, and only weakly increased their movement rates when invertebrate abundances remained low across an entire week. Early in life, godwit chicks may therefore be constrained from increasing their foraging efforts by local environmental conditions, forcing females to sustain higher growth rates late in the season past the local resource peak. Such sex-specific vulnerabilities could lead to lower early-life survival and, in turn, skewed adult sex ratios, which have important implications for population dynamics and persistence.

Behavioral Ecology↗
USGS2026

The collective application of shorebird tracking data to conservation

Addressing urgent conservation issues, such as the drastic declines of North American migratory birds, requires creative, evidence-based, efficient, and collaborative approaches. The abundance of over 50% of monitored North American shorebird populations has declined by over 50% since 1980. To address these declines, we developed a partnership of scientists and practitioners called the Shorebird Science and Conservation Collective (hereafter the collective ). The collective was founded to translate the combined findings of shorebird tracking data into on-the-ground conservation action. With advice from an advisory group, the collective acts as an intermediary whereby dedicated staff collate and analyze data contributions from scientists to support knowledge requests from conservation practitioners. In its first three years, data contributions from 75 organizations include over 7.1 million shorebird observations forming movement paths of 3420 individuals representing 36 species tracked across the Americas and have informed 18 conservation projects spanning education, land and species management, land conservation, and policy requests. Others engaged in translational science from big data could consider similar knowledge-sharing models that prioritize usable data products, foster collaborative engagement between science experts and practitioners, build focused communities around topics or taxonomic groups, and employ a proof-of-concept phase to develop scalable solutions while making progress toward long-term funding to sustain impact. As the volume of scientific data continues to grow, intermediaries, such as the collective, can be vital liaisons to rapidly integrate and interpret research to support conservation action. Dedicated to the memory of Shiloh Schulte and his conservation achievements for shorebirds.

Conservation Biology↗
USGS2025

Power source, data retrieval method, and attachment type affect success of dorsally mounted tracking tag deployments in 37 species of shorebirds

Animal-borne trackers are commonly used to study bird movements, including in long-distance migrants such as shorebirds. Selecting a tracker and attachment method can be daunting, and methodological advancements often have been made by trial and error and conveyed by word of mouth. We synthesized tracking outcomes across 2745 dorsally mounted trackers on 37 shorebird species around the world. We evaluated how attachment method, power source, data retrieval method, relative tracker mass, and biological traits affected success, where success was defined as whether or not each tag deployment reached its expected tracking duration (i.e. all aspects succeeded for the intended duration of the study: attachment, tracking, data acquisition, and bird survival). We conducted separate analyses for tag deployments with remote data retrieval (‘remote-upload tag deployments') and those that archived data and had to be recovered (‘archival tag deployments'). Among remote-upload tag deployments, those that were a lighter mass relative to the bird, were beyond their first year of production, transmitted data via satellite, or were attached with a leg-loop harness were most often successful at reaching their expected tracking duration. Archival tag deployments were most successful when applied at breeding areas, or when applied to males in any season. Remote-upload tag deployments with solar power, satellite data retrieval, or leg-loop harnesses continued tracking for longer than those with battery power, other types of data retrieval, or glue attachments. However, the majority of tag deployments failed to reach their expected tracking duration (71% of remote-upload, 83% of archival), which could have been due to tracker failure, attachment failure, or bird mortality. Our findings highlight that many tag deployments may fail to meet the goals of a study if tracking duration is crucial. Using our results, we provide guidelines for selecting a tracker and attachment to improve success at meeting study goals.

Journal of Avian Biology↗
USGS2024

Migratory strategies across an ecological barrier: Is the answer blowing in the wind?

Background: Ecological barriers can shape the movement strategies of migratory animals that navigate around or across them, creating migratory divides. Wind plays a large role in facilitating aerial migrations, and can temporally or spatially change the challenge posed by an ecological barrier, with beneficial winds potentially converting a barrier to a corridor. Here, we explore the role wind plays in shaping initial southbound migration strategy between two populations departing from different locations along an ecological barrier. Methods: Using GPS satellite transmitters, we tracked the southbound migration of two populations of Short-billed Dowitchers ( Limnodromus griseus caurinus ) from breeding grounds in Alaska to wintering sites in coastal Mexico. The breeding grounds were positioned in distinct regions along an ecological barrier, the Gulf of Alaska. Between the two populations, we compared migratory timing, wind availability at, and tailwind support en route across the Gulf of Alaska. Results: Route choice and arrival timing to wintering sites differed markedly between the two populations: individuals departing from the more westerly site (King Salmon) left at the same time as those from further east (Beluga) but crossed the Gulf of Alaska farther west and arrived along the Pacific coast of Mexico an average of 19 days earlier than their counterparts. Dowitchers from both sites used a slight tailwind to cue departure, but once aloft over the Gulf of Alaska, birds from the more westerly site had up to ten times more tailwind assistance than birds from the more easterly one. Conclusions: The distinct migration strategies, and degree of wind assistance experienced, of these two populations demonstrates how differences in wind availability along migratory routes may form the basis for intraspecific variation in migration strategies with potential carryover effects. Future changes in wind regimes may therefore interact with changes in habitat availability to influence migration patterns and migratory bird conservation.

Alaska↗
USGS2024

The Amazon Basin’s rivers and lakes support Nearctic-breeding shorebirds during southward migration

Identifying the migration routes and stopover sites used by declining species is critical for developing targeted conservation actions. Long-distance migratory shorebirds are among the groups of birds declining most rapidly, yet we frequently lack detailed knowledge about the routes and stopover sites they use during their hemisphere-spanning migrations. This is especially true for species that migrate through mid-continental regions in the Western Hemisphere. We therefore used satellite transmitters to track 212 individuals of 6 shorebird species during their southward migrations— Pluvialis dominica (American Golden-Plover), Limosa haemastica (Hudsonian Godwit), Tringa flavipes (Lesser Yellowlegs), and Calidris subruficollis (Buff-breasted Sandpiper), C. melanotos (Pectoral Sandpiper), and Bartramia longicauda (Upland Sandpiper)—as they crossed the Amazon Basin of South America, a region from which reports of shorebird numbers are increasing but remain relatively rare. Our results make clear that the Amazon Basin provides stopover habitat for a large number of shorebirds: more than 74% of individuals tracked crossing the Amazon Basin stopped over in the region for an average of 2–14 days, with some spending the entire nonbreeding season there. All species selected stopover sites along the region’s many rivers and lakes, while within stopover sites each species exhibited distinct habitat preferences. The timing of stopovers within sub-basins of the Amazon Basin also coincided with periods of low water, when the muddy, shallow water habitats preferred by most shorebirds are likely plentiful. Together, our results highlight the need for detailed investigations into shorebird abundance and distribution within the Amazon Basin, threats to shorebirds within particular subbasins, and links between shorebird conservation efforts and those targeting the myriad other species that inhabit this dynamic, hyper-diverse region.

Amazon Basin↗
USGS2023

Trends and population estimate of the threatened Buff-breasted Sandpiper Calidris subruficollis wintering in coastal grasslands of southern Brazil

Information about population sizes, trends, and habitat use is key for species conservation and management. The Buff-breasted Sandpiper Calidris subruficollis (BBSA) is a long-distance migratory shorebird that breeds in the Arctic and migrates to south-eastern South America, wintering in the grasslands of southern Brazil, Uruguay, and Argentina. Most studies of Nearctic migratory species occur in the Northern Hemisphere, but monitoring these species at non-breeding areas is crucial for conservation during this phase of the annual cycle. Our first objective was to estimate trends of BBSA at four key areas in southern Brazil during the non-breeding season. We surveyed for BBSA and measured vegetation height in most years from 2008/09 to 2019/20. We used hierarchical distance sampling models in which BBSA abundance and density were modelled as a function of vegetation height and corrected for detectability. Next, we used on-the-ground surveys combined with satellite imagery and habitat classification models to estimate BBSA population size in 2019/20 at two major non-breeding areas. We found that abundance and density were negatively affected by increasing vegetation height. Abundance fluctuated five- to eight-fold over the study period, with peaks in the middle of the study (2014/15). We estimated the BBSA wintering population size as 1,201 (95% credible interval [CI]: 637–1,946) birds in Torotama Island and 2,232 (95% CI: 1,199–3,584) in Lagoa do Peixe National Park during the 2019/20 austral summer. Although no pronounced trend was detected, BBSA abundance fluctuated greatly from year to year. Our results demonstrate that only two of the four key areas hold high densities of BBSA and highlight the positive effect of short grass on BBSA numbers. Short-grass coastal habitats used by BBSA are strongly influenced by livestock grazing and climate, and are expected to shrink in size with future development and climatic changes.

Bird Conservation International↗
USGS2022

Dynamic sensitivity to resource availability influences population responses to mismatches in a shorebird

Climate change has caused shifts in seasonally recurring biological events leading to the temporal decoupling of consumer-resource pairs – i.e., phenological mismatching. Although mismatches often affect individual fitness, they do not invariably scale up to affect populations, making it difficult to assess the risk they pose. Individual variation may contribute to this inconsistency, with changes in resource availability and consumer needs leading mismatches to have different outcomes over time. Nevertheless, most models estimate a consumer’s match from a single timepoint, potentially obscuring when mismatches matter to populations. We analyzed how the effects of mismatches varied over time by studying precocial Hudsonian godwit ( Limosa haemastica) chicks and their invertebrate prey from 2009 to 2019. We developed individual and population level models to determine how age-specific variation affect the relationship between godwits and resource availability. We found that periods with abundant resources led to higher growth and survival of godwit chicks, but also that chick survival was increasingly related to the availability of larger prey as chicks aged. At the population level, estimates of mismatches using age-structured consumer demand explained more variation in annual godwit fledging rates than more commonly used alternatives. Our study suggests that modeling the effects of mismatches as the disrupted interaction between dynamic consumer needs and resource availability clarifies when mismatches matter to both individuals and populations.

Alaska↗
USGS2022

Behavioural adjustments in the social associations of a precocial shorebird mediate the costs and benefits of grouping decisions

Animals weigh multiple costs and benefits when making grouping decisions. The cost-avoidance grouping framework proposes that group density, information quality and risk affect an individual’s preference for con or heterospecific groups. However, this assumes the cost–benefit balance of a particular grouping is constant spatiotemporally, which may not always be true. Investigating how spatiotemporal context influences grouping choices is therefore key to understanding how animals contend with changing conditions. Changes in body size during development lead to variable conditions for individuals over short time-scales that can influence their ecological interactions. Hudsonian godwits Limosa haemastica , for instance, form a protective nesting association with a major predator of young godwit chicks, colonial short-billed gulls Larus brachyrhynchus . Godwit broods may avoid areas of higher gull densities when chicks are susceptible to gull predation but likely experience higher risk from alternative predators as a result. Associating with conspecifics could allow godwits to buffer these costs but requires enough other broods with whom to group. To determine how age-dependent predation risk and conspecific density influence godwit grouping behaviours, we first quantified the time-dependent effects of con- and heterospecific interactions on the mortality risk for godwit chicks throughout development. We then determined how godwit density and chick age affected their associations with con- and heterospecific. We found that younger godwit chicks' survival improved with closer association with conspecifics, earlier hatch dates and lower gull densities, whereas older chicks survived better with earlier hatch dates, though this effect was less clear. Concomitantly, godwit broods avoided gulls early in development and when godwit densities were high but maintained loose associations with conspecifics throughout development. We identified how individuals can optimally shift with whom they group according to risks that vary spatially and temporally. Investigating the effects of a species' ecological interactions across spatiotemporal contexts in this way can shed light on how animals adjust their associations according to the costs and benefits of each association.

Journal of Animal Ecology↗
USGS2020

Annual adult survival drives trends in Arctic-breeding shorebirds but knowledge gaps in other vital rates remain

Conservation status and management priorities are often informed by population trends. Trend estimates can be derived from population surveys or models, but both methods are associated with sources of uncertainty. Many Arctic-breeding shorebirds are thought to be declining based on migration and/or overwintering population surveys, but data are lacking to estimate the trends of some shorebird species. In addition, for most species, little is known about the stage(s) at which population bottlenecks occur, such as breeding vs. nonbreeding periods. We used previously published and unpublished estimates of vital rates to develop the first large-scale population models for 6 species of Arctic-breeding shorebirds in North America, including separate estimates for 3 subspecies of Dunlin. We used the models to estimate population trends and identify life stages at which population growth may be limited. Our model for the arcticola subspecies of Dunlin agreed with previously published information that the subspecies is severely declining. Our results also linked the decline to the subspecies’ low annual survival rate, thus potentially implicating factors during the nonbreeding period in the East Asian-Australasian Flyway. However, our trend estimates for all species showed high uncertainty, highlighting the need for more accurate and precise estimates of vital rates. Of the vital rates, annual survival had the strongest influence on population trend in all taxa. Improving the accuracy, precision, and spatial and temporal coverage of estimates of vital rates, especially annual survival, would improve demographic model-based estimates of population trends and help direct management to regions or seasons where birds are subject to higher mortality.

The Condor↗
USGS2019

Geographic variation in the intensity of warming and phenological mismatch between Arctic shorebirds and invertebrates

Responses to climate change can vary across functional groups and trophic levels, leading to a temporal decoupling of trophic interactions or ‘phenological mismatches.’ Despite a growing number of single-species studies that identified phenological mismatches as a nearly universal consequence of climate change, we have a limited understanding of the spatial variation in the intensity of this phenomenon nor what influences this variation. In this study, we tested for geographic patterns in phenological mismatches between six species of shorebirds and their invertebrate prey at ten sites spread across ~13º latitude and ~84º longitude in the Arctic over three years. At each site, we quantified the phenological mismatch between shorebirds and their invertebrate prey at: 1) an individual nest level, as the difference in days between the seasonal peak in food and the peak demand by chicks, and 2) a population level, as the overlapped area under fitted curves for total daily biomass of invertebrates and dates of the peak demand by chicks. We tested whether the intensity of past climatic change observed at each site corresponded with the extent of phenological mismatch and used Structural Equation Modeling to test for causal relationships among: 1) environmental factors, including geographic location and current climatic conditions, 2) the timing of invertebrate emergence and the breeding phenology of shorebirds, and 3) the phenological mismatch between the two trophic levels. The extent of phenological mismatch varied more among different sites than among different species within each site. A greater extent of phenological mismatch at both the individual-nest and population-levels coincided with changes in the timing of snowmelt as well as the potential dissociation of long-term snow phenology from changes in temperature. The timing of snowmelt also affected the shape of the food and demand curves, which determined the extent of phenological mismatch at the population level. Finally, we found larger mismatches at more easterly longitudes, which may be affecting the population dynamics of shorebirds, as two of our study species show regional population declines in only the eastern part of their range. This suggests that phenological mismatches may be resulting in demographic consequences for arctic-nesting birds.

Alaska↗
USGS2018

Life‐history tradeoffs revealed by seasonal declines in reproductive traits of Arctic‐breeding shorebirds

Seasonal declines in breeding performance are widespread in wild animals, resulting from temporal changes in environmental conditions or from individual variation. Seasonal declines might drive selection for early breeding, with implications for other stages of the annual cycle. Alternatively, selection on the phenology of nonbreeding stages could constrain timing of the breeding season and lead to seasonal changes in reproductive performance. We studied 25 taxa of migratory shorebirds (including five subspecies) at 16 arctic sites in Russia, Alaska, and Canada. We investigated seasonal changes in four reproductive traits, and developed a novel Bayesian risk‐partitioning model of daily nest survival to examine seasonal trends in two causes of nest failure. We found strong seasonal declines in reproductive traits for a subset of species. The probability of laying a full four‐egg clutch declined by 8–78% in 12 of 25 taxa tested, daily nest survival rates declined by 1–12% in eight of 22 taxa, incubation duration declined by 2.0–2.5% in two of seven taxa, and mean egg volume declined by 5% in one of 15 taxa. Temporal changes were not fully explained by individual variation. Across all species, the proportion of failed nests that were depredated declined over the season from 0.98 to 0.60, while the proportion abandoned increased from 0.01 to 0.35 and drove the seasonal declines in nest survival. An increase in abandonment of late nests is consistent with a life‐history tradeoff whereby either adult mortality increased or adults deserted the breeding attempt to maximize adult survival. In turn, seasonal declines in clutch size and incubation duration might be adaptive to hasten hatching of later nests. In other species of shorebirds, we found no seasonal patterns in breeding performance, suggesting that some species are not subject to selective pressure for early breeding.

Journal of Avian Biology↗
USGS2018

Effects of environmental conditions on reproductive effort and nest success of Arctic‐breeding shorebirds

The Arctic is experiencing rapidly warming conditions, increasing predator abundance, and diminishing population cycles of keystone species such as lemmings. However, it is still not known how many Arctic animals will respond to a changing climate with altered trophic interactions. We studied clutch size, incubation duration and nest survival of 17 taxa of Arctic‐breeding shorebirds at 16 field sites over 7 years. We predicted that physiological benefits of higher temperatures and earlier snowmelt would increase reproductive effort and nest survival, and we expected increasing predator abundance and decreasing abundance of alternative prey (arvicoline rodents) to have a negative effect on reproduction. Although we observed wide ranges of conditions during our study, we found no effects of covariates on reproductive traits in 12 of 17 taxa. In the remaining taxa, most relationships agreed with our predictions. Earlier snowmelt increased the probability of laying a full clutch from 0.61 to 0.91 for Western Sandpipers, and shortened incubation by 1.42 days for arcticola Dunlin and 0.77 days for Red Phalaropes. Higher temperatures increased the probability of a full clutch from 0.60 to 0.93 for Western Sandpipers and from 0.76 to 0.97 for Red‐necked Phalaropes, and increased daily nest survival rates from 0.9634 to 0.9890 for Semipalmated Sandpipers and 0.9546 to 0.9880 for Western Sandpipers. Higher abundance of predators (foxes) reduced daily nest survival rates only in Western Sandpipers (0.9821–0.9031). In contrast to our predictions, the probability of a full clutch was lowest (0.83) for Semipalmated Sandpipers at moderate abundance of alternative prey, rather than low abundance (0.90). Our findings suggest that in the short‐term, climate warming may have neutral or positive effects on the nesting cycle of most Arctic‐breeding shorebirds.

Ibis↗
USGS2018

Environmental and ecological conditions at Arctic breeding sites have limited effects on true survival rates of adult shorebirds

Many Arctic shorebird populations are declining, and quantifying adult survival and the effects of anthropogenic factors is a crucial step toward a better understanding of population dynamics. We used a recently developed, spatially explicit Cormack–Jolly–Seber model in a Bayesian framework to obtain broad-scale estimates of true annual survival rates for 6 species of shorebirds at 9 breeding sites across the North American Arctic in 2010–2014. We tested for effects of environmental and ecological variables, study site, nest fate, and sex on annual survival rates of each species in the spatially explicit framework, which allowed us to distinguish between effects of variables on site fidelity versus true survival. Our spatially explicit analysis produced estimates of true survival rates that were substantially higher than previously published estimates of apparent survival for most species, ranging from S = 0.72 to 0.98 across 5 species. However, survival was lower for the arcticola subspecies of Dunlin ( Calidris alpina arcticola ; S = 0.54), our only study taxon that migrates through the East Asian–Australasian Flyway. Like other species that use that flyway, arcticola Dunlin could be experiencing unsustainably low survival rates as a result of loss of migratory stopover habitat. Survival rates of our study species were not affected by timing of snowmelt or summer temperature, and only 2 species showed minor variation among study sites. Furthermore, although previous reproductive success, predator abundance, and the availability of alternative prey each affected survival of one species, no factors broadly affected survival across species. Overall, our findings of few effects of environmental or ecological variables suggest that annual survival rates of adult shorebirds are generally robust to conditions at Arctic breeding sites. Instead, conditions at migratory stopovers or overwintering sites might be driving adult survival rates and should be the focus of future studies.

The Auk↗
USGS2017

A global threats overview for Numeniini populations: synthesising expert knowledge for a group of declining migratory birds.

The Numeniini is a tribe of 13 wader species (Scolopacidae, Charadriiformes) of which seven are Near Threatened or globally threatened, including two Critically Endangered. To help inform conservation management and policy responses, we present the results of an expert assessment of the threats that members of this taxonomic group face across migratory flyways. Most threats are increasing in intensity, particularly in non-breeding areas, where habitat loss resulting from residential and commercial development, aquaculture, mining, transport, disturbance, problematic invasive species, pollution and climate change were regarded as having the greatest detrimental impact. Fewer threats (mining, disturbance, problematic native species and climate change) were identified as widely affecting breeding areas. Numeniini populations face the greatest number of non-breeding threats in the East Asian-Australasian Flyway, especially those associated with coastal reclamation; related threats were also identified across the Central and Atlantic Americas, and East Atlantic flyways. Threats on the breeding grounds were greatest in Central and Atlantic Americas, East Atlantic and West Asian flyways. Three priority actions were associated with monitoring and research: to monitor breeding population trends (which for species breeding in remote areas may best be achieved through surveys at key non-breeding sites), to deploy tracking technologies to identify migratory connectivity, and to monitor land-cover change across breeding and non-breeding areas. Two priority actions were focused on conservation and policy responses: to identify and effectively protect key non-breeding sites across all flyways (particularly in the East Asian- Australasian Flyway), and to implement successful conservation interventions at a sufficient scale across human-dominated landscapes for species' recovery to be achieved. If implemented urgently, these measures in combination have the potential to alter the current population declines of many Numeniini species and provide a template for the conservation of other groups of threatened species.

Bird Conservation International↗