Data Zone
Justification of Red List category
This species has an extremely large geographic range size (extent of occurrence >30 million km2 in both the breeding and non-breeding seasons), and so does not approach Criterion B thresholds. It also has a very large estimated population size (1,800,000 to 2,650,000 individuals; Wetlands International 2023), and so does not approach Criteria C or D thresholds. Considering its population trend in North America over three generations (c. 22 years), the data presented in Smith et al. (2023) indicate a rapid decline of c. 70%. This is much steeper than the c. 23% decline reported by the Breeding Bird Survey (Ziolkowski et al. 2022), while numbers recorded by the Christmas Bird Count have remained broadly stable (Meehan et al. 2022). However, all of these North American sources relate to just two of the nine flyway populations globally, and together represent <5% of the global total (Wetlands International 2023). Elsewhere, the three large flyway populations that breed in Iceland, N Europe and W Siberia and winter in Africa are all considered to be stable (van Roomen et al. 2022; Wetlands International 2023). As these three populations together represent c. 90% of the global total, there is no evidence that the population is declining at a rate approaching Criterion A thresholds. Hence, the species continues to warrant listing as Least Concern.
Population justification
The estimated population size of this species is quite large, ranging between 1,800,000 to 2,650,000 individuals (Wetlands International 2023).
Trend justification
Considering its population trend in North America over three generations (c. 22 years), the data presented in Smith et al. (2023) indicate a rapid decline of c. 70% along Atlantic coastline migration sites. Similarly, data from the North American Pacific coast suggest an annual population change of -3.7% (-8.4 to +1%) (Migratory Shorebirds Project, unpubl. data). Both of these sources suggest declines much steeper than the c. 23% decline reported by the Breeding Bird Survey (Ziolkowski et al. 2022), while numbers recorded by the Christmas Bird Count have remained broadly stable (Meehan et al. 2022). However, these North American sources relate to just two of the nine flyway populations globally, and together represent <5% of the global total (Wetlands International 2023). Elsewhere, the three large flyway populations that breed in Iceland, northern Europe and western Siberia and winter in Africa are all considered to be stable (van Roomen et al. 2022, Wetlands International 2023). Together these populations represent c. 90% of the global total, and therefore while a global decline is precautionarily suspected, it is probably occurring at only a very slow rate.
The species has a Holarctic breeding range with two disjunct populations. The western population breeds along coastal Alaska, Yukon Territory, and southwestern Alaska and Yukon. The eastern population breeds west and south of Hudson Bay, extending from northern Manitoba to northern Ontario. During summer, they are found sporadically along the Atlantic coast of the United States, from South Carolina to Florida, and along the Pacific coast from British Columbia to southern Chile and the Falkland Islands. In winter, they irregularly occur along the Pacific coast from southern Vancouver Island to Baja California, and along the Atlantic coast from South Carolina to Florida. They also winter in Central and South America, the Caribbean, and extend across the Old World from Europe to Australia, including various islands in between (Skeel and Mallory 2020).
Behaviour This species is fully migratory and travels over land on a broad front utilising few staging areas on route (in autumn no known concentrated staging occurs) (del Hoyo et al. 1996, Snow and Perrins 1998). It breeds from May to August (Hayman et al. 1986) either in well-dispersed (Johnsgard 1981) solitary pairs (del Hoyo et al. 1996) or in loose groups depending on the topography of the land (Snow and Perrins 1998). The autumn migration occurs from July onwards (Hayman et al. 1986) with the return passage to the breeding grounds occurring chiefly between March and May (Hayman et al. 1986) (non-breeders may also remain on the wintering grounds all year round) (del Hoyo et al. 1996). When not breeding the species usually forages singly or in small groups (del Hoyo et al. 1996), flying in small parties (Johnsgard 1981) or larger flocks on migration (Flint et al. 1984, Snow and Perrins 1998)and roosting communally at night in mangrove trees or in shallow water (del Hoyo et al. 1996). Habitat Breeding The species breeds on dry scrub heathland (Snow and Perrins 1998), moss and lichen tundra with stunted bushes (Johnsgard 1981), sedge meadows (Johnsgard 1981), wet moorland (del Hoyo et al. 1996, Snow and Perrins 1998) and mossy hummock bogs (Johnsgard 1981, Flint et al. 1984) in open areas, river valleys (del Hoyo et al. 1996), along the shores of tundra lakes (Flint et al. 1984), in birch forest near the Arctic treeline (del Hoyo et al. 1996), burned areas of forest (Flint et al. 1984) and open montane forest (del Hoyo et al. 1996) in the boreal, subarctic and subalpine zones (Johnsgard 1981, del Hoyo et al. 1996). It generally avoids extremes of cold and wet, steep slopes, bare rock and gravel expanses or tall dense vegetation (e.g. dense forest) (Snow and Perrins 1998). Non-breeding On passage in the autumn and spring the species frequents wetlands, tidal flats (del Hoyo et al. 1996), short-sward wet and dry grasslands (Hayman et al. 1986, del Hoyo et al. 1996), farmland (Hayman et al. 1986) and heathland with Empetrum spp., generally occupying coastal habitats in the winter such as muddy, rocky or sandy beaches (del Hoyo et al. 1996), coral shores (Urban et al. 1986), exposed reefs, tidal mudflats (del Hoyo et al. 1996), sandflats (Urban et al. 1986), mangrove swamps (del Hoyo et al. 1996), tidal marshes (Johnsgard 1981) and lagoons (Urban et al. 1986). Diet When inland on migration and during the breeding season its diet consists of adult and larval insects (Johnsgard 1981, del Hoyo et al. 1996) (e.g. Coleoptera, Orthoptera and cranefly larvae), spiders, millipedes, earthworms, snails, slugs, seeds, leaves and berries (del Hoyo et al. 1996) (e.g. of ericaceous plants) (Johnsgard 1981). On the coast during the winter the species takes crustaceans (e.g. crabs), molluscs, large polychaete worms and occasionally fish, reptiles or young birds (del Hoyo et al. 1996). Breeding site The nest is a shallow depression (del Hoyo et al. 1996, Snow and Perrins 1998) often positioned on hummocks or in short heather or grass (Johnsgard 1981, Flint et al. 1984) in dry exposed locations (Johnsgard 1981, Flint et al. 1984, del Hoyo et al. 1996) sometimes far from water (Johnsgard 1981, Flint et al. 1984). When the breeding habitat (e.g. tundra or heathland) is flat and open the species nests in solitary pairs, but where irregular features such as hummocks and tall vegetation patches give more visual isolation the species may nest in loose groups (Snow and Perrins 1998). Management information A study in the Shetland Islands, UK found that when trying to enhance the grazing quality of heathlands by re-seeding (e.g. with high quality grass-seed mixtures) it is better to apply lime, grass-seed and inorganic fertiliser directly to the surface of the ground rather than ploughing and harrowing the ground first, as the latter maintains more natural vegetation hummocks and heather used by the species for nesting (Grant 1992). Re-seeding of heathland with prior ploughing and harrowing may improve feeding conditions for pre-breeding adults however (Grant et al. 1992).
Text account compilers
Ekstrom, J., Ashpole, J, Butchart, S., Chad, E., Malpas, L.
Recommended citation
BirdLife International (2024) Species factsheet: Whimbrel Numenius phaeopus. Downloaded from
https://datazone.birdlife.org/species/factsheet/whimbrel-numenius-phaeopus 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.