Nature Of Migration In The Species
Relative to other Scolopacidae and Numenius breeding in North America, Long-billed Curlew is a short-distance migrant. No data available, however, relating populations in specific parts of breeding range to specific wintering areas; thus, some individuals may migrate less than 2,400 km between a northern breeding area and southern wintering area. Compared to some shorebirds whose entire population uses a few stopover areas, Long-billed Curlew migration is characterized as broadly to moderately dispersed, defined as 60% of species occurring about 10 sites .
Timing And Routes Of Migration
Migration patterns poorly understood. Very rare in southeast Saskatchewan in late summer; in contrast, flocks common in southeast Alberta during this same period, leading Renaud (1980) to infer few migrate southeast from Saskatchewan. Birds banded in Idaho reported from both Long Beach, California, and Haiti. Elsewhere on Great Plains outside of breeding range, reported east to southwest Minnesota, central Kansas, and east Oklahoma (e.g., Wagoner County). Sightings in southwest and east-central Arkansas may be individuals wintering in Louisiana or small number that winter farther southeast. Largest numbers in summer/fall reported from Playa Lakes region, Texas. During 2 years, 1,407 and 3,829 counted, making up 10-22% of all shorebirds in the region. From Playa Lakes, movement unclear; may travel southeast to Gulf Coast, continue south into Big Bend region of Texas or central Mexico, or head southwest to Mexico coast.
In spring, noticeably absent from Playa wetlands; 22 and 10 recorded during 2 years. Additional work needed to determine if seasonal difference in abundance is caused by changes in habitat use (e.g., shift from wetland to terrestrial habitats between seasons) or seasonal differences in migration routes. A survey of the Colorado River delta (n = 1 yr) counted 1,248 in fall, 214 in winter, and 2,478 in spring, suggesting the region may be an important stopover area between U.S. and coastal Mexico.
Departs breeding grounds relatively early. Arrives Humboldt Bay, California, by mid-June, all territory holders present by mid-July. In Utah, abundance of breeders on areas around Great Salt Lake declined dramatically after first week of June. In Saskatchewan, groups noticed by mid-July, with most departing from northern parts of range by mid-August and from all parts of breeding range in Saskatchewan and British Columbia by late August. Latest record for Saskatchewan 12 September; the only September record. Small aggregations of postbreeders (30-50) observed as early as third week of July in South Dakota; early August believed to be peak of migration; latest record 25 October. Commonly seen during fall in Kansas, most from 21 August to 25 September. First arrives in Playa Lakes region, Texas, between 28 July and 13 August; numbers peak through September and gone by end of October. Most gone from Great Salt Lake region, Utah, by early September and from east Oregon by October, although reported as late as November in east Oregon. In Sonora, Mexico, migration begins mid-July, but most pass August-September. In Florida, fall migrants arrive beginning in July. In southern-most portion of winter range, has been recorded beginning mid- December in Costa Rica.
Has been recorded in Costa Rica through mid-April. In Sonora, Mexico, migration occurs March through early May. Early-spring arrival dates include 17 February for Texas and 7 February in Nevada; 15 March in southwest Idaho, last week in March for Kansas, South Dakota, Utah, and Oregon; first week in April for British Columbia; 8 April for Saskatchewan; and 16 April for Alberta. Spring peak occurs mid-March in Texas and mid-April in Utah. In British Columbia, arrives earlier than all other shorebirds except Killdeer (Charadrius vociferus); major influxes on interior breeding areas occur late March to early April; most individuals have arrived by late April. Peak arrival mid- to late April in Saskatchewan and Alberta.
No detailed study of behavior during migration. Heard vocalizing in flight during early evening (19:30-20:30) over Humboldt Bay, California, but only during spring; similar behavior recorded during spring in Texas. Large flocks rare. Arrives on breeding areas in small, heterosexual groups. In Saskatchewan, flocks average 2 or 3, with largest flock 7; flocks of 50 reported in British Columbia. Some reports indicated birds arrived paired. Some nonbreeders summer on coastal wintering areas (Colwell and Mathis in press); sex and age unknown. Small flocks of apparent nonbreeders observed on breeding areas in southeast Washington and British Columbia.
In British Columbia, no real evidence of fall staging, rather periodically departs in small flocks; seems typical throughout range. During late summer and migration, flocks of 10-50 common, sometimes 100, with highs of 250 reported in south Washington and 500 in north-central Oregon. Larger groups noted in Sonora, Mexico, where as many as 300 observed at various locations in March, July, October, and December. Composition of small migratory flocks in Utah during fall contained 1 or 2 adults and 2-4 juveniles, leading Paton and Dalton (1994) to suggest that family groups sometimes migrate together.
Thanks to Dugger, Bruce D. and Katie M. Dugger. 2002. Long-billed Curlew (Numenius americanus), The Birds of North America Online (A. Poole, Ed.). species no.628