San Diego Management & Monitoring Program


Long-billed curlew
Numenius americanus


Kingdom Phylum Subphylum Class Order Suborder Family

Current distribution rangewide

Patchily distributed across their current breeding range, spanning 16 U.S states and 3 Canadian provinces [1]. Historical breeding distribution has contracted by about 30 percent [2]. Winter range along coastal and inland habitats primarily found in California, Texas, and Louisiana [1]. In California, found in the San Joaquin Valley, Imperial Valley, portions of the West Mojave, and coastal estuaries [3, cited in 4]. Also found along the Pacific coast from Sonora south to Colima, Mexico, and less numerous south to El Salvador [1].


Known Populations in San Diego County

Most consistent wintering sites in San Diego County are in south San Diego Bay and Tijuana River Estuary [5].


List status

None.


Habitat affinities

Birds of open habitats: upland shortgrass prairies, wet meadows, grasslands, and in winter, agricultural fields, saltwater marshes with tidal channels, intertidal mud flats, and coastal estuaries. At all seasons, flat or gently rolling terrain is characterisitic of curlew habitat [4]. Prefers tidal mudflats and open grassland in San Diego County [5]. Four essential requirements for nesting habitat: short grass (<30sm), bare ground, shade, and abundant invertebrate prey [6].


Taxonomy and genetics

Two recognized subspecies, N. a. americanus and N. a. parvus, occur in California [4] and were divided based on bill length [5].


Seasonal activity

Diurnal [1]. Spring migration begins as early as February in some places, but is generally considered to range from March to April. Most individuals have arrived on their breeding grounds by late April [7, cited in 8]. On breeding grounds, activity may begin about a half hour before dawn, ends at dark as birds arrive at roost site [9]. Leave breeding grounds as early as mid-June, up until late August [1]. Fall migrants arrive in July with numbers peaking in August and September in San Diego County [5].


Life history/ reproduction

Predominantly solitary [4;8]. Seasonally monogamous [1;9;10]. Age at first reproduction is 2 to 3 years for females and 3 to 4 years for males, where they presumably breed every year after they reach breeding age [11]. Nest building begins within 1 week of pairing where both sexes scrape a shallow depression on the ground and the female then lines the nest bowl with small pebbles, bark, grass, and other materials [7;9;12]. Breeding begins mid-April to early May [1]. Clutch size ranges from 3 to 5 eggs [1;13] and laid over 4 to 7 days [Redmond and Jenni 1986]. Both adults incubate and incubation period is 27-30 days [1;11]. Young are precocial and fledge at 38-45 days [9;11;12, cited in 8]. Average life span is 8 to 10 years [11].


Diet and foraging

Diet consists mostly of invertebrates [13;14] with crab or shrimp as the most common prey [14;15]. Fairly opportunistic [13] and will supplement with small vertebrates such as bird eggs and nestlings [16;17,18, both cited in 8]. Use 3 methods to obtain prey: the burrow-probe used primarily in emerged areas, the pause-probe method used only in submerged areas, and the peck method used more infrequently and only on the substrate surface. Often washed muddy prey before consuming [14]


Dispersal

No information.


Threats

Rangewide threats include the loss and degradation of habitat due to urban development, changes in the natural fire regime, and exotic invasive plants [6;19;20;21, cited in 2]. In California, 90% of wetlands in Central Valley have been drained with grasslands either lost to urban growth or converted for agricultural purposes. About 80% of intertidal habitats in San Francisco Bay are gone and existing coastal habitats have changed due to altered hydrology [1].


Long-billed curlew sources