Sora (bird)

Description

Adult soras are 19–30 cm (7.5–11.8 in) long, with dark-marked brown upperparts, a blue-grey face and underparts, and black and white barring on the flanks. They have a short thick yellow bill, with black markings on the face at the base of the bill and on the throat. Sexes are similar, but young soras lack the black facial markings and have a whitish face and buff breast. They weigh about 49–112 g (1.7–4.0 oz).

Habitat

The sora's breeding habitat is marshes throughout much of North America. They nest in a well-concealed location in dense vegetation. The female usually lays 10 to 12 eggs, sometimes as many as 18, in a cup built from marsh vegetation. The eggs do not all hatch together. Both parents incubate and feed the young, who leave the nest soon after they hatch and are able to fly within a month. Soras are commonly reported in plant communities dominated by cattails (Typha spp.), sedges (Carex spp.), bulrushes (Scirpus spp.), smartweeds (Polygonum spp.), rushes (Juncus spp.), rice cutgrass (Leersia oryzoides), and barnyard grasses (Echinochloa spp.).

Outside of wetlands, soras are most often reported in cultivated areas during migration or in the postbreeding period. For instance, a sora was observed 3 mi (4.8 km) from marshland in a cultivated field in Iowa in the middle of August. A male sora was observed less than 1,000 ft (300 m) from a large wetland in a soybean (Glycine max) field in northwestern Iowa during the postbreeding period. From early June to mid-July, soras were observed on farms in Saskatchewan sown mainly with wheat (Triticum aestivum).

Soras have also been reported in flooded wooded areas. In western New York, soras occurred during the breeding season on a study site where 26% of the area was categorized as "flooded timber," and 5% was classed as "scrub/shrub marsh". In eastern and central Maine, an average of 2.1 soras was observed in wooded swamps per 100 hours of observation during the breeding season. On a nonbreeding (August–April) site in southwestern Arizona, soras were found to use a "mixed shrub community" more than expected based on its availability. Soras were observed at low abundances on a site with douglas-fir (Pseudotsuga menziesii), ponderosa pine (Pinus ponderosa), and trembling aspen (Populus tremuloides) in British Columbia.

Soras use areas with a wide range of water depths. They are often observed in water less than 1 ft (30 cm) deep, although the average water depth of sora heavy-use areas in Arizona was 20 in (51 cm). In northwestern Iowa, average water depth in sora territories was 15 in (38 cm), which was significantly (p0.05) different from the height of vegetation in random plots.

In Arizona, both cover and height of vegetation used by soras varied with seasons. Conway suggested the differences likely reflected the varied diet of the sora. The availability of habitat in different seasons is another possible source of seasonal differences in sora habitat.

Extent of woody vegetation surrounding South Dakota wetlands was not significantly (p=0.6) associated with sora occurrence. However, in marshes of western New York, there was a significant (p=0.041) negative relationship between percent flooded timber on a site and sora relative abundance.

Soras may prefer some cover types. In Arizona, 65.3% of sora use was in southern cattail (Typha domingensis), although it comprised only 16.5% of the vegetation. Bulrushes and a mixed-shrub community were also used more than their availability, while saltcedar (Tamarix chinensis) and arrowweed (Pluchea sericea) were avoided. A literature review notes sora avoidance of purple loosestrife (Lythrum salicaria)-dominated sites. In east and central Maine, wetlands used by soras had significantly (p=0.05) more ericaceous vegetation, such as leatherleaves (Chamaedaphne spp.), sweetgales (Myrica spp.), and laurels (Kalmia spp.). In marshes of northwestern Iowa, broadleaf arrowhead (Sagittaria latifolia) occurred in sora territories significantly (p

Migration

They migrate to the southern United States, the Caribbean, and northern South America. Sora is a very rare vagrant to western Europe, where it can be confused with spotted crake. However, the latter species always has spotting on the breast. a streaked crown stripe, and a different wing pattern.

Soras forage while walking or swimming. They are omnivores, eating seeds, insects and snails. Although soras are more often heard than seen, they are sometimes seen walking near open water. They are fairly common, despite a decrease in suitable habitat in recent times. The call is a slow whistled ker-whee, or a descending whinny. The use of call broadcasts greatly increases the chances of hearing a sora. Call broadcasts can also increase the chances of seeing a sora, as they will often investigate the source of the call.

Distribution

Soras occur throughout most of North America. Soras breed from Nova Scotia northwest to southern Yukon and Northwest Territories, south to California, Arizona, and New Mexico and northeast to Pennsylvania and New England. Sora wintering grounds include the Caribbean, northern portions of South America, including Ecuador, Colombia, and Venezuela, north through Central America and Mexico to southern California in the West and coastal regions of the Southeast. From southern Kansas south to northern and eastern Texas and east through the inland areas of the southeastern United States, soras are typically only observed during migration in the spring and fall. In a few areas of the western United States, including central California and areas of Arizona and New Mexico, soras may occur year-round.

Migration

Sora's northern migration occurs in spring, primarily in April and May. For instance, in east-central Kansas significantly (p0.05).

Survival

Few data are available on the survival of soras. Radio-marked soras in Arizona had a nonbreeding survival probability of 0.308. The authors suggest the low survival rate may be due to increased mortality of radio-marked birds. Likely causes of mortality are predation and human-caused sources such as road kill.

Temperature

Temperature may also influence sora abundance. In Colorado, average April temperature was significantly (p

Food habits

Soras eat a wide range of foods. Animals that are commonly reported as sora food items include snails (Gastropoda), crustaceans (Crustacea), spiders (Araneae), and insects (Insecta), mainly beetles (Coleoptera), grasshoppers (Orthoptera), flies (Diptera), and dragonflies (Odonata). Soras often eat the seeds of plants, such as smartweeds, bulrushes, sedges, and barnyard grasses. Seeds of annual wildrice (Zizania aquatica) and rice cutgrass are eaten by soras in the eastern United States. A literature review lists crowngrass (Paspalum spp.) and rice (Oryza sativa) as relatively important food sources for soras in the Southeast. Plants comprising

Predators

Sora eggs are eaten by several species including American minks (Mustela vison), skunks (Mephitidae), coyotes (Canis latrans), grackles (Quiscalus spp.), crows (Corvus spp.), and herons (Ardeidae). Predation of adult soras by American minks, coyotes, hawks and owls have been reported.