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Photo Courtesy of Utah Division of Wildlife Resources
Wilson's Phalarope
Phalaropus tricolor
NatureServe conservation status
Global (G-rank): G5
State (S-rank): S2S3B
External links
General information
Wilson's phalarope, Phalaropus tricolor, breeds in Canada and the northern United States, and winters in southern and western South America. In Utah, it is common in summer and during migration, especially during southward migration in the late summer. As a breeding species in Utah, it occurs mainly in the northern part of the state, and in migration it forms enormous aggregations on the Great Salt Lake. Its breeding habitat is wetlands of interior North America, and its wintering habitat is mainly mudflats and open water of high Andean salt lakes. This species eats small aquatic invertebrates, such as brine shrimp and brine flies, as well as some terrestrial invertebrates and seeds of aquatic plants.
The nest is on damp ground within 100 meters of water. The four eggs are incubated by the male parent alone and hatch in eighteen to twenty-seven days. The nestlings are precocial, leaving the nest cup and capable of swimming within twenty-four hours of hatching; they are not fed by their parents, but feed themselves. They are tended solely by the male parent.
As in the other two species of phalaropes, the usual sex roles are reversed in this species, females being the larger and more colorful gender and males incubating the eggs and tending the young. Females also are occasionally sequentially polyandrous, mating with more than one male.
Species range
BREEDING: coastal British Columbia, southern Yukon, northern Alberta, central Saskatchewan, central Manitoba, southern Ontario, southern Quebec, northeastern New York, and New Brunswick, south to east-central California, central Nevada, central Utah, eastern Arizona, northern New Mexico, northern Texas, central Kansas, western Nebraska, eastern South Dakota, northern Iowa, northern Illinois, northern Indiana, and northern Ohio. Nonbreeders recorded in summer north to central Alaska, central Mackenzie, northern Saskatchewan, and Nova Scotia (McAlpine et al. 1988, AOU 1998). NON-BREEDING: mainly in saline lakes of highlands of western and southern South America, from Peru, Bolivia, Paraguay, and Uruguay south through Chile and Argentina, casually north to central California, Utah, central New Mexico, southern Texas, southwestern Louisiana, and Florida (Colwell and Jehl 1994, AOU 1998).
Migration
Migrates northward through U.S. (mostly over interior prairies west of Mississippi River, uncommon along east coast) mainly April-May (Terres 1980). Migrates regularly through Middle America (September-October and mid-April to late May in Costa Rica), Colombia and Ecuador. Southward migration begins in mid-June (mostly females). The Great Salt Lake (Utah) has the world's largest concentration in fall (500,000-700,000 individuals) (Paton et al. 1992).
Habitat
BREEDING: Shallow freshwater and saline ponds, marshes and wet meadows (AOU 1998). Nests on the ground in wet meadows, grassy marshes, and along edges of shallow inland waters. The nest is a well-concealed scrape, lined with grass. Uses both fresh and alkali wetlands with three characteristics: open water, emergent vegetation, and open shoreline (Saunders 1914, Hohn 1967, Stewart 1975, Prescott et al. 1995, Naugle 1997). Nesting habitat varies widely, including wetlands, wet meadows, upland grasslands, and road rights-of -way (Bent 1927, Roberts 1932, Hohn 1967, Stewart 1975, Murray 1983, Bomberger 1984, Colwell 1987, Colwell and Oring 1990, Einemann 1991, Faanes and Lingle 1995, Dinsmore and Schuster 1997). Occasionally occur in Conservation Reserve Program (CRP) fields and dense nesting cover (Johnson and Schwartz 1993; Prescott et al. 1993; D.H. Johnson, unpubl. data). In North Dakota, densities were highest in undifferentiated tillage wetlands (wetlands with frequently tilled soils), followed by temporary, seasonal, semipermanent, fen, alkali, and permanent wetlands (Kantrud and Stewart 1984). Often occupied the peripheral low prairie and wet-meadow areas of most classes of wetlands in North Dakota. In South Dakota, occurrence was associated positively with the presence of seasonal and semipermanent wetlands, stock ponds, and intermittent streams; area of alfalfa (MEDICAGO SATIVA) hayland; area of surface water; and the percentage of grazed shoreline (Weber 1978, Weber et al. 1982). In eastern South Dakota, the probability of occurrence in semipermanent wetlands was related positively to the proportion of untilled uplands and the number of emergent hydrophyte species (e.g., willow [SALIX spp.]) composing > 10% of the vegetated wetland area; were associated negatively with wetlands dominated by thick-stemmed plants (e.g., cattail [TYPHA spp.] and river bulrush [SCIRPUS FLUVIATILIS]) (Naugle 1997). Within seasonal wetlands, the probability of occurrence was related negatively to wetlands dominated by thick-stemmed plants (Naugle 1997). Nest site selection varies seasonally. Nests in upland vegetation early in the breeding season and wet-meadow vegetation later in the season (Colwell and Oring 1990). Usually nests less than 100 meters from shoreline (Hohn 1967, Hatch 1971, Colwell and Oring 1990, Eldridge in prep.). Nest sites in Nebraska were in wet sedge (CAREX) meadows (Faanes and Lingle 1995). In North Dakota and Iowa, nested in wetlands associated with river floodplains (Murray 1983, Koenig 1984). In Alberta, Saskatchewan, and North Dakota nested in grasses of various heights on islands or in wet-meadow zones around lakes and wetlands; in Saskatchewan, brood rearing occurred in patches of foxtail barley (HORDEUM JUBATUM) (Bent 1927, Hohn 1967, Kagarise 1979, Colwell 1987). In Saskatchewan, Colwell and Oring (1990) found that nest sites had taller, denser, and more homogeneous vegetation and less bare ground than randomly selected sites. However, in the Nebraska sandhills, nest sites had shorter vegetation than random sites (Bomberger 1984). NON-BREEDING: on lake shores, mudflats, salt marshes, freshwater marshes, alkaline ponds; rarely along seacoasts; stages on salt lakes (Colwell and Jehl 1994, AOU 1998). Also at sewage ponds; rarely reported at sea.
Food habits
Eats insects (larvae and adults), especially mosquitoes and crane flies. On salt flats may feed on alkali flies, brine shrimps, seeds of aquatic plants. Feeds as it walks along muddy shores, wades in shallow water, or swims in whirls.
Ecology
Reproductive success varies greatly (17-56%); most clutch failures result from predation (Colwell 1992). Exhibits annual variation in nest site selection, moving to deeper, more permanent wetlands in dry years (Hohn 1967, Colwell 1991).
Reproductive characteristics
In the central and northern Great Plains (Minnesota, Nebraska, and North Dakota), arrives on the breeding grounds from mid-April to early May and departs from mid-August to early September (Roberts 1932, Howe 1972, Johnsgard 1980, Murray 1983). In Alberta, Manitoba, and Saskatchewan, arrives on breeding grounds from late April to early May and is observed until early September (Hohn 1967; Maher 1974; Reynolds et al. 1986; Colwell 1987; Colwell and Oring 1988a,b). Females arrive on the breeding grounds earlier than males (Reynolds et al. 1986, Colwell 1987), and commonly depart from breeding areas earlier than males, usually from early June to early July (Hohn 1967; Howe 1972; Colwell 1987; Colwell and Oring 1988a,b). May renest after nest failure, and females are capable of laying multiple clutches (Colwell and Jehl 1994). Polyandry was first documented in Saskatchewan, where a color-banded female laid two clutches with two individual males (Colwell 1986a, Colwell 1987). Philopatry is uncommon, although males return to breeding areas in successive years more often than females (Colwell 1987, Colwell and Oring 1988b). Of 154 adult male phalaropes banded over four years in Saskatchewan, 16 percent returned to their previous breeding area in successive years, whereas only 2 percent of 69 banded adult females returned (Colwell 1987).
Threats or limiting factors
Declined in some areas due to loss and degradation of wetlands. An accidental and unsuitable host of the Brown-headed Cowbird (MOLOTHRUS ATER), an obligate brood parasite (Friedmann 1963, Hatch 1971).
References
- Colwell, M. A., and J. R. Jehl, Jr. 1994. Wilson’s phalarope. Birds of North America 83: 1–18.
- Behle, W. H., E. D. Sorensen, and C. M. White. 1985. Utah birds: a revised checklist. Utah Museum of Natural History, University of Utah, Salt Lake City. vi + 108 pp.
- Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1988. The birder’s handbook[:] a field guide to the natural history of North American birds. Simon & Schuster, New York. xxx + 785 pp.
