Data Zone
Justification of Red List category
Although uncertain, data from both the non-breeding range and from migration sites indicate that the population has been declining at a moderately rapid to rapid rate of at least 20% over the past three generations. The population size and range remain large. The drivers of these declines are uncertain and require investigation, though actions to secure the availability of favoured temporary shallow wetlands at key points in the annual cycle are expected to benefit the species. As rates of population reduction approach threatened thresholds, Long-billed Dowitcher is assessed as Near Threatened.
Population justification
The breeding population size in Alaska and Canada has been estimated at 674,327 from the Program for Regional and International Shorebird Monitoring (PRISM) (Bart and Smith 2012, Smith et al. in prep.). In addition, an uncertain but large number breed in eastern Siberia in Russia. Comments in Partners in Flight (2023) on population size suggest the Russian population is at least 130,000 (B. Andres 2020, cited in PiF 2023), suggesting the population size is around 800,000 mature individuals. The previous estimate of 500,000 (Andres et al. 2012) appears to have been an underestimate. Elsewhere there is the suggestion that the total population size could be as high as a million birds (Bart et al. in prep.), which is used here as a maximum value.
Trend justification
Analysis of migration count data from a large network of sites across the United States estimates a rate of reduction of 34% over three generations using data from 1980 to 2019 (Smith et al. 2023, also these values are used in Partners in Flight 2023). This data is highly uncertain, with a lower 90% credible interval (LCI 90) of -70% and an upper 90% CI (UCI 90) of +33%. But a rapid recent reduction is supported by data from Audubon’s Christmas Bird Count (CBC), which estimates a 2009-2021 mean annual trend of -5.86% (-18.96 to +1.92) (Meehan et al. 2022), equivalent to -49% (-90 to +23%) over three generations. This data is somewhat skewed by a very high abundance recorded in 2012, but rapid to very rapid declines are evident in California, all around the Gulf states and along the southern eastern seaboard (Meehan et al. 2022). Trend data generated from eBird data in the non-breeding season also indicate a decline, but within rather narrower bounds of -19% (-23 to -14%) over three generations (Fink et al. 2023). In the breeding areas in Alaska, Program for Regional and International Shorebird Monitoring (PRISM) surveys indicated a decline between 2002/2004 (6,848 +/- 3,190) and 2019/2022 (3,190 +/- 1,493) (R. Lanctoc in litt. 2024).
Overall, while there is much uncertainty, moderately rapid to rapid declines appear to apply over the most recent three generation period. Given the level of uncertainty in the migration count data, with credible intervals overlapping zero, the rate of reduction is suspected to fall between 20-29% over the past three generations. This rate is suspected to continue to approach threatened thresholds for several years, at least one generation length into the future (to 2028). However, the slowing of the trend in the migration data (Smith et al. 2023) means that rates over the future three generations are uncertain.
Breeds from the southwestern Taimyr Peninsula eastwards through Siberia, on Wrangel Island, and south to Kamchatka, Russia, western and northern Alaska, United States of America (USA), and northwestern Canada (Takekawa and Warnock 2020). This species winters further north than Short-billed Dowitcher and many other migratory shorebirds in the Americas, with the bulk of the population remaining within the United States and Mexico around the Gulf Coast and Mississippi River valley, as well as in the Central Valley in California and south to the Salton Sea and Gulf of Santa Clara. Birds occur south along the Pacific coast to Panama and along the Caribbean south to Nicaragua (Fink et al. 2023). Very few are considered to regularly winter in South America (Takekawa and Warnock 2020, Fink et al. 2023). The majority of birds fitted with satellite tags in the Alaskan breeding range followed a migration route through the central flyway to winter around the Gulf coast, with some using the Pacific flyway to winter in central California (Kwon and Kempenaers 2023). The Prairie Potholes region is especially important as a staging site during the pre-breeding migration (Skagen and Thompson 2013).
The species breeds in wet, freshwater grass or sedge meadows in the tundra (Takekawa and Warnock 2020). Occurs in a variety of wetland habitats including saline or brackish lagoons on passage and in the non-breeding season (Takekawa and Warnock 2020), but in Mexico noted to move to intertidal flats by the end of the period (Engilis 1998).
Fully migratory, with most birds crossing North America along the central flyway but some passing along the Pacific flyway (Kwon and Kempenaers 2023).
With little clear information on drivers of decline, and little evidence of obvious habitat loss, it is suspected but not clear that there is a reduction in at least the quality of the species' habitat. More research is required to understand if habitat area or extent is declining, and if it is the limiting factor for the species.
The threats causing the recorded population reductions are uncertain. A high proportion of the population relies on wetlands, including flooded agricultural fields during the non-breeding season and along the migratory route, where loss of wetland habitat has been severe throughout the past century, but rates of loss are now at lower levels. During migration, this species relies heavily on temporarily inundated wetlands, which are often individually small areas that may be poorly monitored (Albanese and Davies 2013). The extent of availability of this habitat is dependent on precipitation, such that the average drier conditions under a changing climate in this region could already be reducing availability of a key resource in the pre-breeding season. More research in this area is required. The species is already breeding to the northernmost extent of the landmass. Available breeding habitat based on predicted distribution under future climate change scenarios is predicted to reduce by between 64% (RCP 4.5) and 71% (RCP 8.5) by 2070 (Wauchope et al. 2017).
Using agricultural habitats exposes the species to agricultural chemicals such as DDE that may accumulate to harmful levels, noted in individuals examined in south Texas (White et al. 1983), although data from this study is now 45 years old.
In the past market hunting is thought to have severely impacted the species' population. Currently there seems to be only a very low level of hunting occurring, with small numbers shot when mistaken for snipe around the Gulf Coast (G. Apte in litt. 2024) and perhaps small numbers opportunistically taken by subsistence hunters in Alaska (Naves et al. 2019). Watts et al. (2015) generated a Potential Biological Removal level of 52,420 ± 13,717: current levels of hunting are not thought to be anywhere near this mean level.
Conservation Actions In Place
Protected under the Migratory Birds Act (1927). This species' non-breeding population is part-covered by the Christmas Bird Count (Meehan et al. 2022); it is covered by the International Shorebird Survey during migration (Brown et al. 2001, Smith et al. 2023); and partly covered by the International Waterbird Census during the non-breeding season (Wetlands International 2023).
Conservation Actions Needed
More research is needed to establish drivers of population reductions. Habitat shifts due to climate change may already be affecting the species. Targeted monitoring in non-breeding and migration areas is needed to improve the precision of trend estimates. To support this and other shorebird species during their crucial pre-breeding migrations region-wide wetland management plans are needed to ensure landscape level availability of a mosaic of wetland habitats (Albanese and Davies 2013).
Text account compilers
Martin, R.
Contributors
Lanctot, R. & Apte, G.
Recommended citation
BirdLife International (2024) Species factsheet: Long-billed Dowitcher Limnodromus scolopaceus. Downloaded from
https://datazone.birdlife.org/species/factsheet/long-billed-dowitcher-limnodromus-scolopaceus on 23/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/12/2024.