Data Zone
Justification of Red List category
This species has an extremely large range and large population size. Despite the fact that the population is suspected to have declined recently, the decline is not believed to be sufficiently rapid to approach threatened thresholds. The impact of hunting at key stopover sites during southbound migration may be driving slow declines, possibly in combination with loss of optimal non-breeding and northbound migration habitat, and the potential future impact of climate change on breeding habitat should be assessed though large-scale repeated population monitoring. The species is evaluated as Least Concern.
Population justification
The global population has been estimated at 6 million birds (Bart et al. in prep.), here placed in a band of 1,000,000-6,000,000 mature individuals. This value is based on an extrapolation from the final estimate from the Program for Regional and International Shorebird Monitoring (PRISM) surveys on the breeding grounds (Bart and Smith 2012, Smith et al. in prep.). The final estimate for Arctic Canada was 3,310,745 individuals (Smith et al. in prep.), with an additional c. 300,000 individuals for surveyed parts of northern Alaska (Andres et al. 2012). This surveyed area comprises roughly 60% of the breeding range, hence the final extrapolated estimate of 6 million birds (Bart et al. in prep.). These surveys target breeding pairs in suitable breeding habitat, hence the values derived are considered to relate to mature individuals. It has been noted that extrapolations based on habitat association may be misleading for this species as what appears suitable habitat may contain no birds (Johnson et al. 2021). Hence the extrapolated value here is also treated as a maximum.
Previously the population was estimated to number only c.500,000 individuals (Andres et al. 2012), but this was a value based on only the initial surveys and it was stated that this estimate would increase as the PRISM surveys were completed (Smith et al. in prep). Earlier the suggestion that the population could be 1.0 to 2.5 million pairs (Byrkjedal and Thompson 1998) was considered highly unlikely (Clay et al. 2010). Numbers in non-breeding areas suggest a large proportion of this very large breeding population are unaccounted for by surveys to date. Densities in the grazed pampas in Argentina are reported at 10+ birds per square kilometre (Johnson et al. 2021), which if applied to the whole area of suitable habitat would suggest more than a million individuals are present in this region. A recent approach generating population estimates using Bayesian models on simultaneous large-scale samples along the Atlantic coast between Brazil and Argentina reported a total of 36,038 (95% CI 14,365 to 57,653) individuals (Faria et al. in press), but these surveys did not cover non-coastal sites where most of this species’ population occurs. Large numbers are now thought to winter further north following deforestation increasing the area of suitable habitat, at least in Brazil (Sick 1997), and in native wet pastures in the Brazilian Pantanal it is one of the most numerous Nearctic migrants (A.P. Nunes in litt. 2024).
Trend justification
Data from the breeding areas suggest that a possible moderate to rapid decline has slowed or possibly reversed in the past decade. Trends are available for the Alaska Breeding Bird Survey that indicate a reduction of 36% over the full survey period from 1966-2021 (data from Ziolkowski Jr. et al. 2022). However, data for 2014-2021 suggest an increase equivalent to around 16% over three generations (16.3 years). A linear model of change covering the last three generations of data (2006-2021) gives a reduction of 16% (data from Ziolkowski Jr. et al. 2022). The PRISM surveys in the Arctic National Wildlife Refuge showed no significant trend between 2002/04 and 2019/22, but a slight increase in the point estimate derived (R. Lanctot in litt. 2024), suggesting stability at worse. R. Lanctot (in litt. 2024) also reports a slight increase in individuals detected for the Teshekpuk Lake Special Area, a smaller, well-covered site.
In contrast, surveys of migratory stopover locations throughout North America show a very rapid rate of reduction over the past three generations (Smith et al. 2023, Partners in Flight 2023, Bart et al. in prep.). The annual trend rate is equivalent to a reduction of 56% (95% confidence intervals of -20 to -79%) over three generations. However, there are several reasons that the sites monitored do not allow for adequate sampling of the population to place high confidence in this estimated rate of reduction. Monitoring for this survey takes place throughout the post-breeding migration period and does not sample northbound migration. Many birds undertake long-distance flights over the Atlantic, skipping over the most heavily surveyed areas. Hence only a small, and variable, proportion of the population are available to count at the migration sites each year. The revision of the global population size to greater than a million mature individuals supports the notion that only a very small fraction are detected during migration counts, where average numbers per survey are very low (Smith et al. 2023 [S.O.M Fig. S5]).
Evidence of current declines on the wintering areas is equivocal: flocks are highly mobile and switch favoured sites regularly hence are highly unpredictable and difficult to monitor (Johnson et al. 2021). Azpiroz et al. (2012) reported that the species was declining, but this cited Isacch and Martinez (2003) who reported similar abundance in their study area between 1996-2000 as found in equivalent work during the 1970s (Myers and Myers 1979). However, this site has remained unchanged while habitat conversion occurs elsewhere, hence reductions would be expected elsewhere before becoming evident here (Isacch and Martínez 2003).
There is a trend reported for Christmas Bird Count data (Meehan et al. 2022) equivalent to a 37% exponential reduction for 2006-2021 based on an annual trend derived from hierarchical models (methods in Soykan et al. 2016). However, this data does not cover the main wintering range of the species and cannot be used to infer population level trends.
Considering the breeding data to be the most informative, but noting that the migration count data does report very rapid declines, the population is suspected to have undergone a slow to moderate reduction over the past three generations. Given the very wide uncertainty, this is placed in a band between 0-49%, but with a best estimate of 10-19% reflecting the Alaska BBS data. As these data suggest any reduction is stabilising, and are very uncertain, no rate of reduction is applied for the current or future three generation periods.
The species breeds in the low arctic and subarctic tundra in northern Canada and Alaska (United States of America) (Johnson et al. 2021). It undertakes a long-distance migration to non-breeding areas in grassland and wetlands in interior South America, especially in northern Argentina, but also in Uruguay and southernmost coastal Brazil, and at high-elevation in Bolivia and Peru (Fink et al. 2023). Many also winter patchily along the Pacific coast from Chile to northern Peru and northern Brazil, Guyana, Venezuela and in small numbers in the Caribbean (Johnson et al. 2021, Fink et al. 2023). During spring passage most pass through the centre of the USA from Louisiana and Texas to North Dakota and Saskatchwan, while the majority undertake an initial long-distance post-breeding migration hop direct from north-east Canada to the Caribbean over the Atlantic. Consequently Caribbean islands are of considerable importance during the southbound migration. It has been widely recorded as a vagrant (Johnson et al. 2021, Fink et al. 2023).
Demographic studies indicate survival is the key determinant of population trend for the species (Weiser et al. 2020). Loss of non-breeding and stopover habitat due to conversion of grasslands to agricultural use that is less favourable to the species is suspected to be a major cause of increased mortality, and direct mortality through market hunting at moderately high levels in parts of the Caribbean (AFSI 2020) may be sufficient to cause some declines. Shifting and alteration of habitat due to climate change is also suspected to be affecting reproductive success but is not considered to be causing elevated mortality rates, hence other drivers are likely responsible for any ongoing population reduction.
Text account compilers
Martin, R.
Contributors
Lanctot, R., Apte, G., Ruiz-Guerra, C. & Nunes, A.P.
Recommended citation
BirdLife International (2024) Species factsheet: American Golden Plover Pluvialis dominica. Downloaded from
https://datazone.birdlife.org/species/factsheet/american-golden-plover-pluvialis-dominica on 21/12/2024.
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 21/12/2024.