Eskimo Curlew (Numenius borealis)
Justification There have been no confirmed sightings of the species since the mid-1980s (approximately one generation), and it is considered biologically extinct by a number of authorities. If it is extant, the population must be tiny and it consequently qualifies as Critical.
Identification 29-34 cm. Small cinnamon-coloured curlew. Similar spp. Little Curlew N. minutus is similar, but N. borealis is larger, longer winged (extending beyond tip of tail), shorter legged, cinnamon not buffish below with heavily barred breast and shaped marks on flanks. Small size (25% smaller than Whimbrel N. phaeopus) eliminates all other species. Voice Flight call reportedly a rippling tr-tr-tr and a soft whistle bee bee.
Range & Population Numenius borealis bred at (and presumably between) the Bathurst peninsula and Point Lake in Northwest Territories, Canada. Birds migrated across Hudson Bay to Labrador (and New England, USA), and through the Caribbean to Argentina (especially the Pampas), and possibly Uruguay, southernmost Brazil and Chile south to Patagonia. The return migration was probably along the Pacific coast, through Central America, across the Gulf of Mexico to the Texas coast and northwards through the prairies. It probably numbered hundreds of thousands, but declined rapidly in the 1870s-1890s to become very rare in the 20th century. There are no confirmed recent records (none in South America since 1939), only several unconfirmed reports in 1987-1996. The population (if one persists) probably numbers no more than 25-100 individuals.
Ecology It bred (May-August) in treeless arctic tundra at 180-335 m, comprising grassy meadows with birch (Betula) and sedge (Carex). On autumn migration (July-October), it favoured ericaceous heath, crowberries Empetrum nigrum, pastures and intertidal flats. Winter habitat was possibly wet pampas grasslands, intertidal and semi-desert areas. On return migration (March-May), it favoured burnt areas in tall grass and mixed-grass prairies, and rocky mountain grasshopper Melanoplus spretus was a key food source. It was gregarious, with traditional autumn migration sites.
Threats Spring hunting in North America partially explains the species's near-extinction, but there was no recovery after hunting was outlawed and abandoned in c.1916. The main cause is almost certainly the near total loss of prairies to agriculture, compounded by the suppression of prairie wildfires and the extinction of M. spretus. The widespread conversion of the pampas began after the main decline, but has hindered any possible recovery.
Action CITES Appendix I. CMS Appendix I and II. It is protected in the USA, Canada, Argentina and Mexico. Its status has been fully documented, and identification details publicised. Breeding and wintering areas have been surveyed, and reported breeding sites investigated
