This species has a large geographic range size (extent of occurrence >9 million km² in both the breeding and non-breeding seasons), and so does not approach Criterion B thresholds. It also has a large estimated population size (1,500,000 mature individuals; Partners in Flight 2023), and so does not approach Criteria C or D thresholds. Considering its population trend over three generations (c. 10 years), the data presented in Smith et al. (2023) indicate a small increase of c. 6%, albeit with wide confidence intervals. This is broadly consistent with the c. 14% increase recorded by the Breeding Bird Survey (Ziolkowski et al. 2022). Data from Partners in Flight (2023) suggest that the population may have declined by c. 4%, again with wide confidence intervals. Since the 1980s, declines have been noted at some of the salt lakes where this species congregates on passage, probably associated with drought, but evidence for overall population decrease is inconclusive (Colwell and Jehl 2020). As there is no evidence that the population is declining, it does not approach or meet the thresholds for listing under Criterion A. The species is therefore listed as Least Concern.

Wilson’s Phalarope breeds in wetlands across the western provinces and states of North America (USA and Canada). Isolated nesting has been recorded in areas outside this usual range, including central and south-east Alaska, James Bay, Ontario, New Brunswick, central California, Arizona, New Mexico, Texas, Ohio and Massachusetts (Colwell and Jehl 2020).

The species winters widely but locally in suitable habitats across western and southern South America. Large populations are found in highly saline lakes in the central Andes highlands, from Peru, Chile, and Bolivia to north-west Argentina. Smaller numbers winter in wetlands of north-east and east-central Argentina, and in coastal and interior sites from Peru and Uruguay south to Tierra del Fuego (Colwell and Jehl 2020).

The species has a large estimated population size of 1,500,000 mature individuals (Partners in Flight 2023).

Breeds in interior wetlands including marshes, boggy uplands and coastal marshes. On passage utilises a range of wetland habitats, with the largest congregations observed on large hypersaline lakes of western Canada. Similarly, in the non-breeding season, favours the high salt lakes of the Andes, but also freshwater and alkaline marshes and ponds.

The main threats to this species include the conversion of large areas of North American prairie and wetlands to agricultural land, as well as the degradation of staging and wintering sites. For instance, up to 50% of the population congregates at Great Salt Lake, Utah, where water extraction for agriculture and water quality degradation pose significant threats. The majority of the population winters in the saline lakes of the altiplano in Argentina, Bolivia, and Peru, where mining activities degrade these habitats. Additionally, large concentrations winter in the saline lakes of the Argentine Pampas and Central Chaco, where expanding agriculture and increasing drought severity are concerns. However, given the species' global population trend is considered stable, these threats are not thought to be driving acute population declines.

Conservation Actions Underway
Occurs in numerous protected areas.

Conservation Actions Proposed
Continue to monitor populations. Ensure protection of suitable habitats throughout the breeding and non-breeding ranges, considering potential climate change impacts and planning for habitat corridors for expansion. Advocate for responsible agricultural practices that balance economic viability, environmental sustainability, and social equality. Support the development of agricultural certification for livestock and crops that promote conservation of Wilson’s Phalarope and other wetland and grassland species. Promote integrated water management to maintain water quality and availability at critical breeding, staging, and wintering areas, ensuring natural water levels during peak usage periods (Lesterhuis and Clay 2010).