Data Zone
Justification of Red List category
Although this species has a relatively small breeding range size (extent of occurrence c. 1,500,000 km2), this still far exceeds Criterion B thresholds. It also has a relatively small estimated population size (70,000 mature individuals; Partners in Flight 2023), but again this does not approach Criteria C or D thresholds. Considering its population trend over three generations (c. 18 years), data from the Christmas Bird Count (Meehan et al. 2022) indicate a decline of c. 23% (albeit with wide confidence intervals), although the underlying interannual trend data suggest the population has fluctuated over the last decade, following a long-term decline. Over the same period, Partners in Flight (2023) reports a decline of c. 11% (albeit with large confidence intervals), and eBird also indicates a decline (Fink et al. 2023). Although the population has declined and may still be declining, it does not currently appear to be declining at a rate approaching Criterion A thresholds. Hence, the species continues to warrant listing as Least Concern.
Population justification
It has a relatively small estimated population size (70,000 mature individuals; Partners in Flight 2023), but this does not approach Criteria C or D thresholds.
Trend justification
Considering its population trend over three generations (c. 18 years), data from the Christmas Bird Count (Meehan et al. 2022) indicate a decline of c. 23% (albeit with wide confidence intervals), although the underlying interannual trend data suggest the population has fluctuated over the last decade, following a long-term decline. Over the same period, Partners in Flight (2023) reports a decline of c. 11% (albeit with large confidence intervals), and eBird also indicates a decline (Fink et al. 2023). Although the population has declined and may still be declining, it does not currently appear to be declining at a rate approaching Criterion A thresholds.
Breeds in the high alpine tundra of Alaska and Yukon and winter in rocky intertidal habitats along the Pacific coast from Alaska to southern South America (Senner and McCaffery 2020).
Causes of suspected declines unknown. The species was scored a moderate oil vulnerability score of 54, with scores ≥ 60 being considered high concern. The 1989 Exxon Valdez oil spill affected areas close to important habitats but had limited direct impact on the species. Analysis of birds from the spill area showed higher phytane levels but no significant hydrocarbon contamination. Much of the alpine breeding habitat is secure within protected public lands. However, coastal migration and wintering habitats are vulnerable to oil pollution and increasing human development, particularly from Vancouver Island southwards, increasingly encroach on feeding and roosting areas (Senner and McCaffery 2020).
Text account compilers
Ekstrom, J., Everest, J., Chad, E., Butchart, S.
Recommended citation
BirdLife International (2024) Species factsheet: Surfbird Calidris virgata. Downloaded from
https://datazone.birdlife.org/species/factsheet/surfbird-calidris-virgata on 23/11/2024.
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 23/11/2024.