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 very 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.
Continental populations were thought to be declining by 2% per year between 1980 and 1996 (equivalent to 16% in ten years) (AOU 1998, Hill 1998); however data from the North American Breeding Bird Survey indicate that these figures were incorrect and in fact annual declines at a rate of 0.6% between 1980 and 2006 are more realistic (Morrison et al. 2006). This equates to a decline of just 5.8% over a ten year period. However, it appears that there are considerably more Long-billed Curlews than previously thought, with a likely global population in the order of 50,000-123,000, based on recent assessments, expert opinion and statistically based surveys (Wetlands International 2006).
This species has undergone a small or statistically insignificant decrease over the last 40 years in North America (data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007).
This species was once an abundant breeder over most of the prairie regions of the USA and Canada. Populations have declined throughout this range since the beginning of the 20th century as a result of over-hunting and habitat loss (owing to fragmentation, conversion to croplands, and urban development). It is now extirpated as a breeding bird in Kansas, Michigan, Iowa, Minnesota, Wisconsin, eastern Nebraska, Illinois, Manitoba and south-east Saskatchewan. It migrates to winter in the southern USA and Mexico, with birds occurring irregularly in Guatemala, Honduras, El Salvador and Costa Rica (AOU 1998, Hill 1998).
Breeding habitat is short-grass or mixed-grass native prairie, but varies from moist meadows to very dry grasslands. It generally prefers to nest in large open expanses of relatively low vegetation, and is late maturing, long-lived and has a low reproductive output. In winter it favours intertidal habitats but will feed in adjacent pastures (Leeman and Colwell 2005).
Sea-level rise may reduce the amount of available intertidal wintering habitat in future (Colwell and Mathis 2001). The loss and conversion of large areas of short grass prairie into agricultural land within its range has presumably had a major impact upon the species and is likely to the most important threat at present. Long-billed Curlew are facing increasing threats in the grasslands and prairies of North America, both on their breeding and wintering grounds. In addition, Long-billed Curlew range contractions on the eastern edge of their range continue to cause concerns.
Conservation Actions Underway
CMS Appendix II. The American bird Conservancy has worked to increase awareness of the species as a flagship for grassland conservation in the Northern Rockies (Anon 2006/2007). Population surveys have been conducted and global population estimates generated. It occurs within a number of protected areas and areas of short grass prairie are being conserved for it and other species's benefit.
Text account compilers
Butchart, S., Benstead, P., Bird, J., Mahood, S.
BirdLife International (2023) Species factsheet: Numenius americanus. Downloaded from http://datazone.birdlife.org/species/factsheet/long-billed-curlew-numenius-americanus on 28/05/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 28/05/2023.