WatchList Species Account for Eskimo Curlew (Numenius borealis)

Qualifies for the list as a Red List Species

Photo: USFWS

The Eskimo Curlew bred on the treeless tundra of the arctic and subarctic of Canada and Alaska and wintered in the grasslands of southern South America. With a population once presumed in the hundreds of thousands, it declined suddenly between the 1870s and 1890s; sightings of the species in the 20th Century have been very rare, with 4 birds reported from Argentina in 1990 and at least 4 apparently reliable reports since 1987 along the Texas coast.

Several causes have been put forth as theories to explain the species’ extremely rapid demise. Among them are unregulated and intense hunting pressure and loss of habitat due to suppression of fire and conversion to agriculture that destroyed the curlew’s stopover sites during spring migration; related to the latter is the rapid extinction of one of its main food sources, the Rocky Mountain grasshopper, which went from being a serious agricultural pest to extinction in only a hundred years. These factors were compounded by the curlew’s social system; it was long-lived, had a single 4-egg clutch subjected to changes in weather and predation on its arctic breeding grounds, it apparently relied on relatively few sites during migration, and it had one of the longest and most demanding migrations of any shorebird through a rapidly altered landscape.

It is postulated that the loss of a single stopover site can have great effects on some migratory species, and during the 19th Century it is likely that the curlew lost several. In that century there was also a marked climate change throughout the Arctic. A few may still exist, but with such low numbers it may be impossible for a curlew to locate a mate on its vast arctic breeding ground.