The Long-billed Curlew (Numenius americanus) is the largest shorebird, and the most southerly breeding curlew, in North America. Once abundant over most of the prairie regions of the United States and Canada, populations of the Long-billed Curlew have declined throughout most of the species' breeding range since the early 1900s as a result of both overhunting and habitat loss. Long-billed Curlews are currently on the Blue List of species that may be at risk of declining to nonviable population levels in Alberta in the event of further reductions in population, habitat, and/or provincial distribution.
The breeding habitat of Long-billed Curlews is typically described as shortgrass or mixedgrass native prairie but varies from moist meadows to very dry grasslands. Within certain parameters, curlews appear to be somewhat flexible in their breeding habitat preferences. In general, Long-billed Curlews prefer to nest in areas with large open expanses of relatively low vegetation. Curlew foraging efforts are hampered in years in which weather conditions resulted in abundant thick, standing-dead vegetation.
Long-billed Curlews are a late-maturing, long-lived species with low reproductive output. Females lay only one clutch each breeding season and only one case of a re-nesting attempt following nest failure has been recorded.
Young Long-billed Curlews are precocial (able to walk and feed themselves shortly after hatch) and hatch at the same time. Adults lead their chicks to areas of dense vegetative cover shortly after hatching where invertebrates, such as grasshoppers, constitute the majority of the diet for both adults and young. Adult curlews may also feed upon small amphibians. Major predators on curlew eggs include: Coyotes, Black-billed Magpies, Bullsnakes, Common Ravens, and Badgers. In addition to these predators, curlew chicks are also vulnerable to predation by Ferruginous Hawks, Swainson's Hawks, and Great Horned Owls.
Long-billed Curlews rely upon the cryptic colouration of their plumage and eggs to avoid predation and will crouch low on the nest in the presence of potential avian predators. The effectiveness of this crypsis may be enhanced when breeding territories are located within large tracts of unfragmented habitat. Adult curlews actively defend their eggs and young by feigning injury to lead predators away, and by calling and diving at predators. Non-incubating curlews often assist neighbours in attempts to drive predators away. Curlew breeding territories are frequently clumped in loose aggregations and it has been suggested that this aids in predator defense.
Like many species in which both parents incubate the eggs, the female Long-billed Curlew often abandons the brood 2 to 3 weeks after hatching. Thereafter, the male cares for the young until they are old enough to survive on their own -- generally 41 to 45 days after hatching. In July and August, adults and juveniles join post breeding flocks prior to migration and, by the end of August, Long-billed Curlews leave Alberta.