Data Zone
Justification of Red List category
This small shorebird has declined moderately rapidly according to recent monitoring. There is considerable uncertainty in the rate of the reduction, but it is estimated to fall between 20-29% over the past three generations and for the period projected to the near future. At present, the population size and range remain large. Due to the rate of population reduction, the species is assessed as Near Threatened.
Population justification
The population was estimated as 700,000 in 2012 (Andres et al. 2012) but was recently substantially revised upwards. Arctic PRISM surveys in the species' Canadian range identified a population of c.2.6 million birds, but these surveys covered only c.10% of the species' range (Bart et al. in prep.). This led the latter authors to precautionarily estimate a population size of c.5 million, but when accounting for the large area of suitable habitat in Alaska, this seems to be the minimum plausible population size. Here, an estimate of 5,000,000-15,000,000 breeding individuals is used.
Trend justification
Population trend previously estimated to be stable (data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007). However the majority of both the breeding and wintering range of the species are poorly covered by these surveys, and migration surveys are considered to cover a greater portion of the population and consequently generate more reliable trends. Smith et al. (2023) used updated migration count data on the Atlantic coast to estimate a population reduction equivalent to 36.2% over three generations, though with wide confidence intervals between a reduction of 61.58% and an increase of 1.5%. This data is also used in the Avian Conservation Assessment Database December 2023 update (Partners in Flight 2023). Other datasets also suggest declines in this species, albeit ones that are less alarming. On the Pacific coast the Migratory Shorebirds Project (unpublished data) has estimated rates of decline equivalent to 26% over three generations. Across North America, using eBird data between 2011 and 2021, Fink et al. (2023) estimated declines of a much slower rate equivalent to 5% over three generations.
To incorporate the range of uncertainty within these data, the rate of reduction is here estimated to fall within the wide band of 0-62%, with the best estimate between 20-29% over three generations.
Breeds chiefly in subarctic tundra and far northern boreal forest over much of North America (Canada and Alaska, USA). It then migrates on a broad front across North America, with eastern populations wintering in north-east South America. Western populations migrate through interior North America to the Gulf Coast and Central America, or down the Pacific Coast to north-west South America (Nebel and Cooper 2020).
Breeds in wetlands, wet meadows and uplands above the tree-line in wet sedge and grassy bogs (Nebel and Cooper 2020, Bart et al. in prep.). On staging and non-breeding grounds, it has a preference for grassy, muddy or sandy substrates (vs rocky).
The drivers of decline in this species are very poorly known but likely include dams and water management, loss of wetlands driven by urban, agriculture and aquaculture development, the impacts of domestic, industrial and agricultural pollution, and climate change (Nebel and Cooper 2020, Bart et al. in prep.). The latter has been identified as driving reduced breeding productivity by a number of mechanisms in other shorebirds worldwide (e.g. Meltofte et al. 2007, Eikelenboom 2016, Kubelka et al. 2018) but more research on its impacts on this species specifically is urgently needed.
On passage and in its non-breeding range, likely threats probably include habitat loss and degradation, human disturbance and perhaps locally hunting (Andres et al. 2022).
Conservation Actions Underway
No targeted actions are known, although the species is covered by PRISM survey monitoring in the Canadian Arctic.
Conservation Actions Proposed
Protect and preserve important staging and non-breeding areas. Research threats, particularly on the breeding grounds, to better understand the mechanisms of population declines. Continue regular monitoring to determine population trends.
Text account compilers
Butchart, S., Berryman, A., Ekstrom, J., Symes, A.
Recommended citation
BirdLife International (2024) Species factsheet: Least Sandpiper Calidris minutilla. Downloaded from
https://datazone.birdlife.org/species/factsheet/least-sandpiper-calidris-minutilla on 24/11/2024.
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 24/11/2024.