Western Hemisphere Shorebird Reserve Network Research Articles

Movement and habitat use of non‐breeding Semipalmated Sandpiper (Calidris pusilla) at the Banco dos Cajuais in Northeast Brazil

AbstractSemipalmated sandpipers are Arctic breeding shorebirds that migrate to South America during the non‐breeding season. Little work has been done to understand the daily movements, foraging habits and metabolic state of this species on stationary nonbreeding grounds. Our work was conducted at the Banco dos Cajuais Western Hemisphere Shorebird Reserve Network (WHSRN) site in Northeast Brazil. We captured semipalmated sandpipers in February and March 2019 and 2020 and attached nanotags to monitor their daily movements. Blood samples were taken to measure plasma triglycerides (an index of fattening rate). We also conducted behavioral observations on foraging birds. Using tracking data we determined that most semipalmated sandpipers appeared to use sunrise/sunset as an indicator for movement between salina and tidal flat habitats, and a smaller portion used tidal height. We found birds spent similar amounts of time foraging on tidal flats and in salinas, though different foraging modes were used. Plasma triglyceride measures suggest semipalmated sandpipers had not started preparing to migrate when sampled. We successfully tracked semipalmated sandpipers to North America during northward migration in 2020, detecting eight within the United States. Tracking results suggest many stopped elsewhere in South America to fuel for migration, though some may have fueled at the Banco dos Cajuais. By demonstrating substantial use of both natural and altered habitats in the region by migrant semipalmated sandpipers, these data highlight the need for broader conservation measures throughout coastal regions of South America.

Shorebird Surveys of the Lahontan Valley Nevada, 1986–2019, with Recommendations on Monitoring and Management

Stillwater National Wildlife Refuge and Carson Lake and Pasture are the key components of the Lahontan Valley wetlands, designated in 1988 as a site of hemispheric importance in the Western Hemisphere Shorebird Reserve Network. In 1990, Congress authorized transfer of Carson Lake and Pasture from federal ownership to the state of Nevada, provided that the area be managed consistent with its designation as part of the network. To enhance protection and management of the site, and specifically to inform development of a management plan for Carson Lake and Pasture, we analyzed spring and fall surveys for shorebirds, 1986–2019, archived by the Nevada Department of Wildlife. Over the 34 years of surveys, we documented 28 species, 19 of which occurred in ≥50% of the years surveyed. Annual counts of all shorebirds combined exceeded 100,000 in 24% of the survey years and 20,000 in 94%. Annual counts of the American Avocet (Recurvirostra americana) exceeded 10% (45,000 individuals) of the estimated global population in three years, and of the Long-billed Dowitcher (Limnodromus scolopaceus; 50,000 individuals) in two years. On the basis of their numbers and frequency of occurrence or status as species of national conservation concern, we identified these two species plus nine others as priorities for management. We recommend conducting more consistent surveys and identifying specific opportunities to manage water quantity and quality, vegetation, livestock grazing, or other factors to benefit shorebirds.

Identification of priority shorebird conservation areas in the Caribbean.

Despite being geographically central to the Atlantic Americas Flyway for migratory birds, the Caribbean is often overlooked or underappreciated when addressing the conservation of North American shorebirds. To our knowledge, this is the first Caribbean-wide assessment of shorebird use in the region. We analyzed 211,013 shorebird species observations in the insular Caribbean from 2010–2019, representing 78,794 eBird checklists and cumulative total of 2.1 million shorebirds of 45 species. We conclude that priority areas for shorebird conservation include Humedal Sur de Pinar del Río (Humedal Sur de Los Palacios) in Cuba, and Monte Cristi in the Dominican Republic as they each likely support more than 20,000 shorebirds annually, and they host large abundances of geographic populations for particular taxa. Specifically, the former site hosts >10% of Short-billed Dowitchers (Limnodromus griseus griseus/hendersoni), and >1% of Black-bellied Plovers (Pluvialis squatarola cynosurae) and Wilson’s Plovers (Charadrius wilsonia wilsonia), while the latter site supports large numbers of Black-necked Stilts (Himantopus mexicanus). We also identified at least 15 additional sites that likely cross the 1% population threshold for one or more shorebird taxa. These sites may qualify for special international designations such as Important Bird and Biodiversity Areas or as part of the Western Hemisphere Shorebird Reserve Network; 11 of the 17 sites we identified do not hold either of these titles. Data on subspecific or geographic distributions of three species, Snowy Plover (C. nivosus), Black-necked Stilt, and Killdeer (C. vociferous), are insufficient to reveal if the sites with the highest abundances were mostly comprised of Caribbean populations or migrants, but the limited information suggests that they also likely exceed 1% thresholds on several islands. Based on our results, we recommend more extensive systematic surveys of shorebirds in the Caribbean, including research on turnover rates and movements between islands, as well as assimilation of shorebird survey data not yet included in the eBird portal.

Waterbird Migration through a Saline Wetland in the Western Nevada Desert, USA

A great variety of waterbirds migrate across western Nevada, where places to rest or refuel are nearly non-existent. One exception is a little-known industrial pond complex at the Albemarle U.S., Inc. facility in Silver Peak. In this paper we analyzed 3 years (2014-2016) of near-daily counts to document the timing, abundance, and stopover biology of 73 species traversing one of the driest regions in North America. Average annual bird-use-days exceeded 350,000, of which 93% were contributed by species with affinities to highly saline habitats. Individuals of most species (total estimated 110,000-183,000) passed through within a day or so, although some Ruddy Ducks (Oxyura jamaicensis), Eared Grebes (Podiceps nigricollis) and American Avocets (Recurvirostra americana) made prolonged stays. We treat the most abundant species in detail and show that data from sites that can be monitored daily can complement studies from sites where daily censuses are not feasible. The Silver Peak ponds attract sufficient shorebirds to warrant consideration as a Site of Regional Importance in the Western Hemisphere Shorebird Reserve Network.

Florida's Strategic Position for Collaborative Automated Telemetry Tracking of Avian Movements Across the Americas

Florida's Strategic Position for Collaborative Automated Telemetry Tracking of Avian Movements Across the Americas

Annual and Seasonal Variation in Shorebird Abundance in the St. Lawrence River Estuary during Fall Migration

Many north American shorebird populations are declining. it is therefore urgent to identify major sites used during their annual cycle to achieve effective conservation measures. our objective was to expand some aspects of the knowledge base needed to assess the ecological value of the St. Lawrence River Estuary for shorebird conservation. Here, we present the results of the most intensive shorebird survey ever conducted in the St. Lawrence River Estuary during fall migration. Surveys were conducted between St-Jean-Port-Joli and St-Simon-sur-Mer, Quebec, Canada, in 2011 and 2012, from late June/early July through late november, corresponding to the migration period of all species potentially present in the study area. The Semipalmated Sandpiper (Calidris pusilla) was one of the two most abundant species during both years of our study (most abundant species, followed by Dunlin [Calidris alpina] and Black-bellied Plover [Pluvialis squatarola] in 2011; second to Blackbellied Plover in 2012). Considering the entire shorebird community, abundance of individuals peaked in early September. Peak abundance occurred earlier for adults than for juveniles. For most species, juveniles largely outnumbered adults. Juveniles were relatively less abundant in 2012 than in 2011. This reflected a general trend observed in northeastern north America between those years, suggesting a lower breeding success in 2012. Given its importance as a staging site for juvenile birds (study area used annually by up to a few hundred thousand shorebirds) and therein, its conservation value, we recommend that the St. Lawrence River Estuary should be included within the Western Hemisphere Shorebird Reserve network.

Metals from mine waste as potential cause of oxidative stress in burrowing crab Neohelice granulata from San Antonio bay

The Natural Protected Area San Antonio bay is of particular importance for its congregation of migratory shorebirds and it has been declared one of the Western Hemisphere Shorebird Reserve Network International site (WHSRN). Present study represents the first assessment of variation on oxidative stress biomarkers in male crab Neohelice granulata from San Antonio bay (Río Negro, Argentina) under field conditions, associated mainly to metal contamination coming from passive mining wastes. Three sites were sampled once every three months from November 2012 to August 2013 within this sea inlet (Pile, Fishery and Port) and a control site at the southeast of the bay (Punta Perdices). Accumulation of Ni, Zn, Cr and Al varied only with seasons although without a constant trend, meanwhile Cd, Cu and Pb also varied among sites being highest in Pile and Port. Biochemical results indicated that variations in catalase activity was only site specific being maximum in Pile; meanwhile lipid radical, α-tocopherol and metallothioneins were only seasonal specific being higher in autumn and winter. Seasonal variation was also found for total thioles, being the content higher in summer and autumn than in winter. Correlation analysis revealed that malondialdehyde and α-tocopherol have a positive association with Al and negative with Ni, meanwhile GST has a positive association with Fe. Crabs from the closest area to the waste pile did not exhibit a differentiated oxidative pressure despite the higher accumulation of metals. It is possible that crabs from contaminated areas have developed a tolerance to metals, indicating a strong ecotoxicological selective pressure. More studies are needed to assess whether there is a transfer of metals through the food chain.

Recent desiccation of Western Great Basin Saline Lakes: Lessons from Lake Abert, Oregon, U.S.A.

Although extremely important to migrating waterfowl and shorebirds, and highly threatened globally, most saline lakes are poorly monitored. Lake Abert in the western Great Basin, USA, is an example of this neglect. Designated a critical habitat under the Western Hemisphere Shorebird Reserve Network, the lake is at near record historic low levels and ultra-high salinities that have resulted in ecosystem collapse. Determination of the direct human effects and broader climate controls on Lake Abert illustrates the broader problem of saline lake desiccation and suggests future solutions for restoration of key habitat values. A 65-year time series of lake area was constructed from Landsat images and transformed to lake volume and salinity. “Natural” (without upstream withdrawals) conditions were calculated from climate and stream flow data, and compared to measured volume and salinity. Under natural conditions the lake would have higher volume and lower salinities because annual water withdrawals account for one-third of mean lake volume. Without withdrawals, the lake would have maintained annual mean salinities mostly within the optimal range of brine shrimp and alkali fly growth. Even during the last two years of major drought, the lake would have maintained salinities well below measured values. Change in climate alone would not produce the recent low lake volumes and high salinities that have destroyed the brine shrimp and alkali fly populations and depleted shorebird use at Lake Abert. Large scale withdrawal of water for direct human use has drastically increased the imbalance between natural runoff and evaporation during periods of drought in saline lakes worldwide but could be offset by establishing an “environmental water budget” to lay a foundation for the conservation of saline lake habitats under continued threats from development and climate change.

Shorebird Abundance and Distribution on the Coastal Plain of the Arctic National Wildlife Refuge

Abstract Abstract The coastal plain of the Arctic National Wildlife Refuge hosts seven species of migratory shorebirds listed as highly imperiled or high priority by the U.S. Shorebird Conservation Plan and five species listed as Birds of Conservation Concern by the U.S. Fish and Wildlife Service. During the first comprehensive shorebird survey of the 674 000 ha “1002 Area” on the coastal plain, we recorded 14 species of breeding shorebirds at 197 rapidly surveyed plots during June 2002 and 2004. We also estimated detection ratios with a double counting technique, using data collected at 37 intensively studied plots located on the North Slope of Alaska and northern Canada. We stratified the study area by major habitat types, including wetlands, moist areas, uplands, and riparian areas, using previously classified Landsat imagery. We developed population estimates with confidence limits by species, and estimated the total number of shorebirds in the study area to be 230 000 (95% CI: 104 000–363 000), which exceeds the biological criterion for classification as both a Western Hemisphere Shorebird Reserve Network Site of International Importance (100 000 birds) and a Ramsar Wetland of International Importance (20 000 birds), even when conservatively estimated. Species richness and the density of many species were highest in wetland or riparian habitats, which are clustered along the coast.

Unusually Sensitive Areas (USAs) for Ecological Resources: Maps and GIS Data for the United States

ABSTRACT The U.S. Department of Transportation, Research and Special Programs Administration (RSPA), Office of Pipeline Safety (OPS) is required to identify areas unusually sensitive to environmental damage in the event of a hazardous liquid pipeline accident. Pipeline segments where a release could impact an USA are subject to additional prevention, mitigation, and response measures than what has previously been implemented by pipeline operators. Ecological USAs have been identified and mapped for the entire United States using data and expertise from many different sources. The final mapping product was completed at Research Planning, Inc, Columbia, South Carolina and was sent to OPS for distribution to the pipeline operators. USAs are selected from a set of candidate resources that include federally threatened and endangered species, imperiled species (generally 20 or fewer known populations world-wide), depleted marine mammals, and high concentration areas for migratory waterbirds. Final USAs include all critically imperiled species (generally 5 or fewer known populations world-wide), multi-species assemblages (three or more overlapping candidate resource types), Ramsar sites (areas designated under the Convention on Wetlands of International Importance Especially as Waterfowl Habitat), Western Hemisphere Shorebird Reserve Network (WHSRN) sites, high quality candidate occurrences (condition or viability of a species occurrence as determined by the Natural Heritage Programs) and candidate species that are aquatic dependent or terrestrial with limited home range sizes. RSPA's Geographic Information System (GIS) model integrates state Natural Heritage Program data, Environmental Sensitivity Index (ESI) data, Ramsar and WHSRN data and maps, hydrography, and species habitat and range classifications assigned by project ecologists. A summary map of all ecological USAs is presented at a nation-wide scale. The map provides specific examples as given by OPS, of regions: Southern, Southwest, Central, Eastern, and Western. States with high concentrations of liquid pipelines are also presented. This project and its results are unique in that they represent one of the first nation-wide compilations of ecological data for the purposes of a standardized pipeline risk assessment.

Monitoring Species Richness and Abundance of Shorebirds in the Western Great Basin

Broad-scale avian surveys have been attempted within North America with mixed results. Arid regions, such as the Great Basin, are often poorly sampled because of the vastness of the region, inaccessibility of sites, and few ornithologists. In addition, extreme variability in wetland habitat conditions present special problems for conducting censuses of species inhabiting these areas. We examined these issues in assessing multi-scale shorebird (order: Charadriiformes) censuses conducted in the western Great Basin from 1992-1997. On ground surveys, we recorded 31 species of shorebirds, but were unable to accurately estimate population size. Conversely, on aerial surveys we were able to estimate regional abundance of some shorebirds, but were unable to determine species diversity. Aerial surveys of three large alkali lakes in Oregon (Goose, Summer, and Abert Lakes) revealed > 300,000 shorebirds in one year of this study, of which 67% were American Avocets (Recurvirostra americana) and 30% phalaropes (Phalaropus spp.). These lakes clearly meet Western Hemisphere Shorebird Reserve Network guidelines for designation as important shorebird sites. Based upon simulations of our monitoring effort and the magnitude and variation of numbers of American Avocets, detection of 5-10% negative declines in populations of these birds would take a minimum of 7-23 years of comparable effort. We conclude that a combination of ground and aerial surveys must be conducted at multiple sites and years and over a large region to obtain an accurate picture of the diversity, abundance, and trends of shorebirds in the western Great Basin.

The Importance of Subarctic Intertidal Habitats to Shorebirds: A Study of the Central Yukon-Kuskokwim Delta, Alaska

A 6-year study of shorebird use of intertidal habitats of the Yukon-Kuskokwim Delta revealed this area to be one of the premiere sites for shorebirds throughout the Holarctic and worthy of designation as a Hemispheric Shorebird Reserve in the Western Hemisphere Shorebird Reserve Network. The study area, which covered 10% (300 km2) of the delta's intertidal flats, regularly hosted 17 species of shorebirds between late April and mid-October. The greatest use was during the postbreeding period (late June-October), when Dunlins (Calidris alpina), Western Sandpipers (C. mauri), and Rock Sandpipers (C. ptilocnemis), each with large local nesting populations, accounted for 95% of the shorebirds recorded. Peak counts during autumn approached 300,000 birds. Considering the seasonal occurrence and turnover of populations, we estimate 1-2 million shorebirds use the central delta each year. The delta supports large fractions of the Pacific Rim or world populations of Bar-tailed Godwits (Limosa lapponica), Black Turnstones (Arenaria melanocephala), Red Knots (C. canutus), Western Sandpipers, Dunlins, and Rock Sandpipers. Densities of shorebirds using the central delta's four major bays and connecting coastal areas peaked at 950 shorebirds/km2 in early September. Hazen Bay frequently hosted more than 1,200 shorebirds/km2. Postbreeding shorebirds used intertidal habitats in three distinct patterns according to age class. For most species (n = 7), there was a period when adults appeared first, followed by a brief interval when adults and juveniles mixed, then by a prolonged period when only juveniles remained. In the second pattern (n = 3 species), adults moved onto the intertidal flats first, were later joined by juveniles for a prolonged staging period, then migrated with them. In the third pattern (n = 3 species), only juveniles used the delta's intertidal habitat. Temporal segregation among species and age groups may minimize competition for food and thereby allow the delta to support high diversity and numbers of shorebirds.