Geology topics

Daniel R. Ruthrauff

Publications and source records attributed to Daniel R. Ruthrauff.

At least 19 recordsLinked to original sources

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

Post-hatch ecology, diet, and first migration of juvenile Alaskan Bar-tailed Godwits

Life stages between hatching and adult recruitment are poorly described for most migratory shorebird species and represent a critical knowledge gap in understanding long-term population dynamics. We conducted a pilot study on the Seward Peninsula, Alaska, to assess the feasibility of following juvenile Bar-tailed Godwits Limosa lapponica baueri from their breeding grounds to their non-breeding grounds in New Zealand and Australia. Radio-tracked broods were highly mobile and moved hundreds to thousands of meters per day. They used low-elevation wetlands with dense shrub cover when younger, and more open, tundra-dominated ridgetops when older. Using DNA metabarcoding analysis of fecal samples, we found that chick diet consisted largely of flying insects (e.g. Tenthredinidae and Ichneumonidae) and small gastropods and appeared to increase in diversity with chick age. We followed one brood to near-fledging (ca. 26 days old) and deployed 5-g satellite transmitters on three chicks. One of these subsequently moved to the Yukon-Kuskokwim Delta, from where it flew 11 days and an estimated 13,391 km to Tasmania, which is the longest non-stop flight recorded for landbirds. These results provide the first information on the ecology of pre- and post-fledging young Bar-tailed Godwits in Alaska, and will inform future efforts to study this important life stage.

Alaska↗

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↗

USGS2024

A circumpolar study unveils a positive non-linear effect of temperature on arctic arthropod availability that may reduce the risk of warming-induced trophic mismatch for breeding shorebirds

Seasonally abundant arthropods are a crucial food source for many migratory birds that breed in the Arctic. In cold environments, the growth and emergence of arthropods are particularly tied to temperature. Thus, the phenology of arthropods is anticipated to undergo a rapid change in response to a warming climate, potentially leading to a trophic mismatch between migratory insectivorous birds and their prey. Using data from 19 sites spanning a wide temperature gradient from the Subarctic to the High Arctic, we investigated the effects of temperature on the phenology and biomass of arthropods available to shorebirds during their short breeding season at high latitudes. We hypothesized that prolonged exposure to warmer summer temperatures would generate earlier peaks in arthropod biomass, as well as higher peak and seasonal biomass. Across the temperature gradient encompassed by our study sites (>10°C in average summer temperatures), we found a 3-day shift in average peak date for every increment of 80 cumulative thawing degree-days. Interestingly, we found a linear relationship between temperature and arthropod biomass only below temperature thresholds. Higher temperatures were associated with higher peak and seasonal biomass below 106 and 177 cumulative thawing degree-days, respectively, between June 5 and July 15. Beyond these thresholds, no relationship was observed between temperature and arthropod biomass. Our results suggest that prolonged exposure to elevated temperatures can positively influence prey availability for some arctic birds. This positive effect could, in part, stem from changes in arthropod assemblages and may reduce the risk of trophic mismatch.

Global Change Biology↗

USGS2023

Disparate data streams together yield novel survival estimates of Alaska-breeding Whimbrels

Survival estimates are critical components of avian ecology. In well-intentioned efforts to maximize the utility of one's research, survival estimates often derive from data that were not originally collected for survival assessments, and such post hoc analyses may include unintentional biases. We estimated the survival of Whimbrels captured and marked at two breeding sites in Alaska using divergent data streams that in isolation were subject to methodological biases. Although both capture sites were chosen to study the migration ecology of Alaska-breeding Whimbrels, maximizing the conservation value of the data we collected was obviously desirable. We used multi-year telemetry information to infer survival from one site (Colville River) and mark-resight techniques to estimate survival from a second site (Kanuti River). At the Colville River, we could not feasibly include a control group of birds to assess potential survival effects of externally mounted transmitters, while at Kanuti River we were unable to accurately account for potential emigration events because we used resightings alone. We integrated these datasets in a Bayesian hierarchical framework, an approach that permitted insights across sites that moderated methodological biases within sites. Using telemetry enabled us to detect permanent emigration events from breeding sites in two of ten birds; results that informed estimates for birds without tracking devices. These datasets yielded point estimates of true survival of Whimbrels from Colville River equipped with solar-powered satellite transmitters that were higher (0.83) than true survival estimates of Whimbrels from Kanuti River marked with leg flags alone (0.74) or equipped with surgically implanted satellite transmitters (0.50), but the 95% credible intervals on these estimates overlapped across groups. For species like Whimbrels that are difficult and costly to study, combining information from disparate data streams allowed us to derive novel demographic estimates, an approach with clear application to other similar studies.

Alaska↗

USGS2022

The Pacific as the world’s greatest theater of bird migration: Extreme flights spark questions about physiological capabilities, behavior, and the evolution of migratory pathways

The Pacific Basin, by virtue of its vastness and its complex aeroscape, provides unique opportunities to address questions about the behavioral and physiological capabilities and mechanisms through which birds can complete spectacular flights. No longer is the Pacific seen just as a formidable barrier between terrestrial habitats in the north and the south, but rather as a gateway for specialized species, such as shorebirds, to make a living on hemispherically distributed seasonal resources. This recent change in perspective is dramatic, and the research that underpins it has presented new opportunities to learn about phenomena that often challenge a sense of normal. Ancient Polynesians were aware of the seasonal passage of shorebirds and other landbirds over the Pacific Ocean, incorporating these observations into their navigational “tool kit” as they explored and colonized the Pacific. Some ten centuries later, systematic visual observations and tracking technology have revealed much about movement of these shorebirds, especially the enormity of their individual nonstop flights. This invites a broad suite of questions, often requiring comparative studies with bird migration across other ocean basins, or across continents. For example, how do birds manage many days of nonstop exercise apparently without sleep? What mechanisms explain birds acting as if they possess a Global Positioning System? How do such extreme migrations evolve? Through advances in both theory and tracking technology, biologists are poised to greatly expand the horizons of movement ecology as we know it. In this integrative review, we present a series of intriguing questions about trans-Pacific migrant shorebirds and summarize recent advances in knowledge about migratory behavior operating at temporal scales ranging from immediate decisions during a single flight, to adaptive learning throughout a lifetime, to evolutionary development of migratory pathways. Recent advances in this realm should stimulate future research across the globe and across a broad array of disciplines.

Ornithology↗

USGS2021

Life-history attributes of Arctic-breeding birds drive uneven responses to environmental variability across different phases of the reproductive cycle

Animals exhibit varied life-history traits that reflect adaptive responses to their environments. For Arctic-breeding birds, traits related to diet, egg nutrient allocation, clutch size, and chick growth are predicted to be under increasing selection pressure due to rapid climate change and increasing environmental variability across high-latitude regions. We compared four migratory birds (black brant [ Branta bernicla nigricans ], lesser snow geese [ Chen caerulescens caerulescens ], semipalmated sandpipers [ Calidris pusilla ], and Lapland longspurs [ Calcarius lapponicus ]) with varied life histories at an Arctic site in Alaska, USA, to understand how life-history traits help moderate environmental variability across different phases of the reproductive cycle. We monitored aspects of reproductive performance related to the timing of breeding, reproductive investment, and chick growth from 2011 to 2018. In response to early snowmelt and warm temperatures, semipalmated sandpipers advanced their site arrival and bred in higher numbers, while brant and snow geese increased clutch sizes; all four species advanced their nest initiation dates. During chick rearing, longspur nestlings were relatively resilient to environmental variation, whereas warmer temperatures increased the growth rates of sandpiper chicks but reduced growth rates of snow goose goslings. These responses generally aligned with traits along the capital-income spectrum of nutrient acquisition and altricial–precocial modes of chick growth. Under a warming climate, the ability to mobilize endogenous reserves likely provides geese with relative flexibility to adjust the timing of breeding and the size of clutches. Higher temperatures, however, may negatively affect the quality of herbaceous foods and slow gosling growth. Species may possess traits that are beneficial during one phase of the reproductive cycle and others that may be detrimental at another phase, uneven responses that may be amplified with future climate warming. These results underscore the need to consider multiple phases of the reproductive cycle when assessing the effects of environmental variability on Arctic-breeding birds.

Alaska↗

USGS2021

Bar-tailed Godwits Limosa lapponica in Alaska: Revisiting population estimates from the staging grounds

Bar-tailed Godwits Limosa lapponica baueri breed in Alaska and spend the nonbreeding season primarily in eastern Australia and New Zealand. Long-term declines spurred recent surveys at nonbreeding sites that yielded a revised population estimate of ~126,000 godwits. We conducted aerial surveys for Bar-tailed Godwits in 2018 and 2019 at pre-migratory staging sites in western Alaska. Counts from similar surveys in 1997 accorded with counts of baueri from the nonbreeding range. Instead of relying on observer estimates of flock sizes, we enumerated 97% of our survey totals using digital photography. Our survey results differed markedly between 2018 (39,751) and 2019 (100,926), differences that reflected a relatively late autumn survey period in 2018, when some godwits were likely to have left the area, compared to 2019. In contrast to the 1997 surveys, we found few Bar-tailed Godwits at estuaries on the Alaska Peninsula. However, we counted nearly 93,000 godwits (~92% of survey total) along ~60 km of coast at the Kuskokwim River Delta in 2019, a value constituting nearly three-quarters of the subspecies’ current population estimate. Our survey totals for 2019 were in agreement with contemporaneous counts at austral nonbreeding sites, demonstrating how aerial surveys from Alaska can provide useful insights into counts conducted elsewhere in the subspecies’ range. When combined with measures of reproductive output, estimates of seasonal survival, and dedicated studies of the movement and survival of juvenile godwits, future surveys from Alaska can further contribute to efforts to determine mechanisms of population changes in baueri Bar-tailed Godwits.

Alaska↗

USGS2021

Physiomorphic transformation in extreme endurance migrants: Revisiting the case of bar-tailed godwits preparing for trans-pacific flights

In a 1998 paper entitled “Guts don’t fly: small digestive organs in obese bar-tailed godwits,” Piersma and Gill (1998) showed that the digestive organs were tiny and the fat loads huge in individuals suspected of embarking on a non-stop flight from Alaska to New Zealand. It was suggested that prior to migratory departure, these godwits would shrink the digestive organs used during fuel deposition and boost the size and capacity of exercise organs to optimize flight performance. Here we document the verity of the proposed physiomorphic changes by comparing organ sizes and body composition of bar-tailed godwits Limosa lapponica baueri collected in modesty midway during their fueling period (mid-September; fueling, n = 7) with the previously published data for godwits that had just departed on their trans-Pacific flight (October 19; flying, n = 9). Mean total body masses for the two groups were nearly identical, but nearly half of the body mass of fueling godwits consisted of water, while fat constituted over half of total body mass of flying godwits. The two groups also differed in their fat-free mass components. The heart and flight muscles were heavier in fueling godwits, but these body components constituted a relatively greater fraction of the fat-free mass in flying godwits. In contrast, organs related to digestion and homeostasis were heavier in fueling godwits, and most of these organ groups were also relatively larger in fueling godwits compared to flying godwits. These results reflect the functional importance of organ and muscle groups related to energy acquisition in fueling godwits and the consequences of flight-related exertion in flying godwits. The extreme physiomorphic changes apparently occurred over a short time window (≤1 month). We conclude that the inferences made on the basis of the 1998 paper were correct. The cues and stimuli which moderate these changes remain to be studied.

Frontiers in Ecology and Evolution↗

USGS2021

Diverse patterns of migratory timing, site use, and site fidelity by Alaska-breeding Whimbrels

Birds that conduct long-distance migrations exhibit varied patterns of consistency in migratory timing and site use. Understanding variation in these traits among populations can help uncover mechanisms driving migratory behaviors and identify potential population threats. Whimbrels ( Numenius phaeopus ) are long-distance migratory shorebirds with a Holarctic breeding distribution, and recent studies have documented population-specific migrations that vary in duration (short to long) and frequency of stops (none/few to multiple). Factors driving these population-specific differences are unclear. We studied the migration ecology of Whimbrels breeding in Alaska, USA, using satellite transmitters deployed from 2006 to 2010 and tracked through 2015. Whimbrels moved entirely within the Pacific Americas Flyway, and some conducted nonstop flights that exceeded seven days across ~ 8700 km. Birds dispersed across numerous sites throughout the flyway, often using agriculture or aquaculture habitats. Whimbrels generally exhibited fidelity to breeding and non-breeding sites, but typically only exhibited fidelity to staging sites used prior to long, nonstop migratory flights. The duration of migration for Whimbrels at more southern non-breeding locations was longer than for those at more northern non-breeding sites, and birds at more southern sites also terminated southbound migration later and initiated northbound migration earlier than birds at more northern sites. Alaska-breeding Whimbrels exhibited greater variation in migratory behaviors than those in other populations in the species’ range. We attribute this within-population diversity to the extensive breadth of non-breeding distributions (~ 70° latitude across ~ 8600 km), a range that naturally shaped individual responses to unequal migratory demands.

Alaska↗

USGS2020

Shorebird reproductive response to exceptionally early and late springs varies across sites in Arctic Alaska

While increases in overall temperatures are widely reported in the Arctic, large inter-annual variation in spring weather, with extreme early and late conditions, is also occurring. Using data collected from three sites in Arctic Alaska, we explored how shorebird breeding density, nest initiation, nest synchrony, nest survival, and phenological mismatch varied between two exceptionally early (2015 and 2016) and late (2017 and 2018) springs. We assessed these differences in the context of long-term data from each site and whether species exhibited conservative or opportunistic reproductive strategies. Conservative shorebirds typically display nest-site fidelity and territoriality, consistent population densities, relatively even individual spacing, and monogamous mating systems with bi-parental incubation. In contrast, opportunistic shorebirds display the opposite traits, and a polygamous mating system with uniparental incubation. In this study, we evaluated 2,239 nests from 13 shorebird species, 2015–2018, and found that shorebirds of both strategies bred earlier and in higher numbers in early, warm springs relative to historic levels (based on 3,789 nests, 2005–2014); opposite trends were observed in late springs. In early springs, nests were initiated less synchronously than in late springs. Nest survival was unrelated to spring type, but was greater in earlier laid nests overall. Invertebrate food resources emerged earlier in early springs, resulting in a greater temporal asynchrony between invertebrate emergence and chick hatching in early than late springs. However, invertebrate abundance was quite variable among sites and years regardless of spring type. Overall, our results were generally consistent with predicted relationships between spring conditions and reproductive parameters. However, we detected differences among sites that could not be explained by other ecological factors (e.g., predators or alternative prey). Differences in shorebird community composition and other subtler methodological/ecological differences among sites highlight the difficulty of understanding the complex nature of these ecological systems and the importance of evaluating questions at multiple sites across multiple years. Our study demonstrates that shorebirds exhibit a high degree of behavioral flexibility in response to variable Arctic conditions, but whether this flexibility is enough to allow them to optimally track changing environmental conditions or if evolutionary adjustments will be necessary is unknown.

Alaska↗

USGS2020

Shorebird research at the U.S. Geological Survey Alaska Science Center

Shorebirds—which include sandpipers, plovers, and oystercatchers—are perhaps best known by their presence on sandy beaches, running along the water’s edge while they probe for food. But they are probably less recognized for their impressive long-distance migrations. Millions of individuals travel from across the globe to breed throughout Alaska each spring, making these birds a familiar and important part of local wildlife communities and Alaska Native cultures. Unfortunately, many shorebird populations have steeply declined worldwide. Because shorebirds use the same coastal habitats as humans, anthropogenic development can lead to habitat loss that degrades the extent and quality of coastal sites important to these species. However, Alaska has an abundance of intact coastal ecosystems that provide important breeding and migratory stopover sites for shorebirds, making the State one of the world’s most critical sites for shorebirds. The focus of shorebird research at the U.S. Geological Survey Alaska Science Center is to help identify important breeding and migratory sites, and to investigate the causes of the declines in many shorebird populations.

Fact Sheet↗

USGS2020

Through thick and thin: Sexing Bristle-thighed Curlews Numenius tahitiensis using measures of bill depth

Birds often exhibit diagnostic traits that differ among individuals of the same species with regard to factors like sex, age, or breeding status. Shorebirds exhibit a wide diversity of colors, shapes, and sizes of their bills, and these traits are commonly used to determine the sex of individuals. In curlews (genus Numenius), length alone accurately separates the sexes in some species, but the shape of the bill has not typically been assessed for this purpose. We collected a suite of measurements on the bills of known-sex Bristle-thighed Curlews N. tahitiensis and determined that standardized measurements of bill depth separated the sexes with high accuracy. A model incorporating the length of a bird’s diagonal tarsus and multiple measurements of the bill was 93.1% accurate in predicting the sex of individual Bristle-thighed Curlews. Simpler models involving only the values of the bill depth near the tip and the base of the bill, however, produced similarly accurate results and are preferred for their parsimony. We advocate the use of one such model that is 93.4% accurate in determining the sex of Bristle-thighed Curlews. As a simple heuristic, a value for the ratio of the bill depth near the tip to that at the base of >0.5 indicated a female, providing an easy field calculation to help determine the sex of Bristle-thighed Curlews. In general, the bills of female Bristle-thighed Curlews are deeper and taper relatively less than those of males. Other observers have qualitatively noted apparent sex-specific differences in the shape of curlew bills, but the generality of our quantitative findings remains to be examined in other curlew species.

Wader Study↗

USGS2019

Survival of Bristle-thighed Curlews equipped with externally mounted transmitters

Telemetry devices are widely used in avian research, but the degree to which the deployment of such devices affects the survival of study subjects is often not addressed. It is generally assumed that such effects are less pronounced in large-bodied species that conduct relatively short migrations and carry relatively light telemetry devices. We studied Bristle-thighed Curlews Numenius tahitiensis over the period 2012–2017 at a nonbreeding site on the island of Oahu, Hawaii. We used leg-loop harnesses to equip 11 curlews with externally mounted, solar-powered satellite transmitters that constituted ca. 3% of their body mass, and compared the annual survival of these birds to 37 curlews marked only with uniquely engraved leg flags. Despite the species’ large size and the small mass of the transmitters, we documented potential negative effects of externally mounted transmitters on the survival of Bristle-thighed Curlews. We also documented apparent effects of age and sex on the survival of curlews, underscoring the difficulty of disentangling the effects of research techniques on study subjects. Understanding and publicizing the potential effects of research itself on wildlife are crucial steps in the process of refining technical applications and improving the welfare of study animals. We urge researchers to critically assess and report the effects of similar research techniques to minimize deleterious effects in future studies.

Wader Study↗

USGS2019

Shorebird subsistence harvest and indigenous knowledge in Alaska: Informing harvest assessment and management, and engaging users in shorebird conservation

Limited data on harvest and population parameters are major impediments to assess shorebird harvest sustainability. Because of sharp declines in shorebird populations, timely conservation efforts require approaches that account for uncertainty in harvest sustainability. We combined harvest assessment and ethnographic research to better understand shorebird conservation concerns related to subsistence harvest in Alaska and to support culturally sensible conservation actions. Our objectives were to (1) estimate the Alaska-wide shorebird subsistence harvest and (2) document shorebird indigenous knowledge on the Yukon-Kuskokwim Delta. Harvest estimates were based on surveys conducted in 1990–2015 (n = 775 community-years). Key respondent interviews conducted in 2017 (n = 72) documented shorebird ethnotaxonomy and ethnography. The Alaska-wide shorebird harvest was 2,783 birds per year. Harvest of godwits was relatively low (1,115 birds per year) and likely included mostly Bar-tailed Godwits Limosa lapponica baueri, but this population has a low harvest potential. The egg harvest was 4,676 eggs per year, mostly small shorebird eggs. We documented 24 Yup’ik shorebird names and 10 main ethnotaxonomic categories. Children learning harvesting skills focused on small birds and adults also occasionally harvested shorebirds, but shorebirds were not primary food or cultural resources. Older generations associated shorebirds with a time when people were in closer contact with nature and their cultural roots. Shorebirds connected people with the environment as well as with Yup’ik traditions and language. Our results can inform improvements to harvest assessment and management, as well as outreach and communication efforts to engage subsistence users in shorebird conservation.

Alaska↗