LC
Whimbrel Numenius phaeopus



Justification

Justification of Red List Category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Population justification
The global population is estimated to number c.1,000,000-2,300,000 individuals (Wetlands International 2015). National population estimates include: c.1,000-10,000 individuals on migration and c.50-1,000 wintering individuals in China; c.1,000-10,000 individuals on migration and c.50-1,000 wintering individuals in Taiwan; c.1,000-10,000 individuals on migration and c.50-1,000 wintering individuals in Japan and c.10,000-100,000 breeding pairs and > c.10,000 individuals on migration in Russia (Brazil 2009). The European population is estimated at 343,000-402,000 pairs, which equates to 687,000-805,000 mature individuals (BirdLife International 2015).

Trend justification
The overall population trend is decreasing, although some populations may be stable and others have unknown trends (Wetlands International 2015). This species has undergone a large and statistically significant decrease over the last 40 years in North America (-84.7% decline over 40 years, equating to a -37.5% decline per decade; data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007) Note, however, that these surveys cover less than 50% of the species's range in North America. In Europe the population size is estimated to be stable (BirdLife International 2015).

Ecology

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).

Threats

The species is susceptible to avian influenza so may be threatened by future outbreaks of the virus (Melville and Shortridge 2006).

Conservation actions

Conservation Actions Underway
The species is listed on Annex II (B) of the EU Birds Directive.

Conservation Actions Proposed
The following information refers to the species's European range only: A study in the Shetland Islands, U.K. 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).

Acknowledgements

Text account compilers
Ashpole, J, Butchart, S., Ekstrom, J., Malpas, L.


Recommended citation
BirdLife International (2017) Species factsheet: Numenius phaeopus. Downloaded from http://www.birdlife.org on 19/10/2017. Recommended citation for factsheets for more than one species: BirdLife International (2017) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/10/2017.