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COSEWIC Assessment and Status Report on the Yellow Rail in Canada
- Assessment Summary
- Executive Summary: from the 1999 Status Report
- COSEWIC Mandate, Membership and Definitions
- Lists of Figures and Tables
- Species Information
- Population Size and Trend
- Summary of Population Size, Number of Breeding Localities and Trends
- General Biology
- Limiting Factors
- Special Significance of the Species
- Evaluation and Proposed Status
- Technical Summary
- Acknowledgements, Biographical Summary of the Authors, and Literature Cited
from the 1999 Status Report
The Yellow Rail (Coturnicops noveboracensis) resembles a week-old chicken. Its minute size, buffy plumage with black and white markings, very short tail, light eyebrow, and small bill are reminiscent of a quail; hence its genus name Coturnicops, meaning “that looks like a quail”. It is one of the smallest rails in the world, weighing only 60 g (females weigh slightly less) and measuring 15-19 cm, only slightly longer than a House Sparrow (Passer domesticus). The tips of the secondary remiges are white, forming a white wing patch that is visible in flight. As in all rails, the body is laterally compressed, and the long toes are used to maneuver through the aquatic vegetation.
Adult and young Yellow Rails can sometimes be confused with Soras (Porzana carolina), and the two species’ breeding ranges overlap considerably in Canada. However, adult Soras have a black face and throat and a grey breast. Also, adults and young have longitudinal stripes on the back, in contrast to the Yellow Rail’s transversal stripes. In addition, the absence of a white wing patch in adult and young Soras is an excellent way of distinguishing the two species in flight.
Except for a very small area in Mexico where a few birds may still breed, the Yellow Rail breeds exclusively in Canada and the northern U.S. It winters near the east coast from North Carolina to eastern Texas. Its imperfectly known breeding distribution seems to be quite local and disjunct.
Population Size and Trends
According to the authors of the report, there might be roughly a few thousand pairs of Yellow Rails breeding in the Hudson/James Bay region, and another roughly 2000 pairs in the rest of Canada. The U.S. may have about 600-750 breeding pairs. Habitat has declined and is still declining throughout its southern breeding range, albeit more slowly than formerly. It may also be declining in certain parts of the Hudson/James Bay region as a result of habitat degradation by Snow Geese (Chen caerulescens). The relatively small wintering range is also declining.
Nesting Yellow Rails are typically associated with marshes dominated by sedges, true grasses, and rushes, where there is little or no standing water (generally 0-12 cm) and where the substrate remains saturated throughout the summer. They can be found in damp fields and meadows, on the floodplains of rivers and streams, in the herbaceous vegetation of bogs, and at the upper levels (drier margins) of estuarine and salt marshes. Nesting habitats usually have a dry mat of dead vegetation from previous growing seasons. A greater diversity of habitat types is used during migration and winter than during the breeding season. In winter, Yellow Rails are known to use coastal wetlands and rice fields.
Yellow Rails probably start breeding when they are a year old. Pair formation likely occurs on the breeding grounds. Males may breed successively with two or more females, at least in captivity. When several pairs breed in the same marsh, activity areas of nesting birds overlap somewhat.
Females have only one brood per season, although females that do not hatch their first clutch may renest. Both males and females share the first stage of nest building, making crude scrapes in the vegetation. The nest usually rests on the ground or just a few centimeters above it, and is typically covered with a concealing canopy of dead vegetation. The 7-10 eggs are laid a day apart. Incubation, carried out by the female alone, usually begins when laying is complete and continues for 17-18 days. Hatching is synchronous, and within a few hours the semiprecocial young can stand. Hatching success is likely very high. Two days after hatching, the entire brood follows the hen away from the nest. The chicks begin to feed themselves at about five days, are no longer brooded at three weeks, and fledge by 35 days. Age at independence is unknown.
During daylight hours the Yellow Rail usually walks or runs, but almost never flies unless disturbed. It is particularly difficult to see upon approach, because, like other rails of its genus it usually remains stationary in the vegetation rather than fleeing as do other rails. Males call much more often and regularly at night than during daytime. Yellow Rail adults eat invertebrates and seeds. The diet of chicks is unknown.
Wetland loss by agriculture and human development is unquestionably the greatest threat to the Yellow Rail, both in Canada and in the U.S., and there is no doubt that the population has been affected by habitat loss and degradation. Habitat loss is occurring even in the last pristine stronghold, the Hudson/James Bay region. However, it is unclear how much of a problem this currently poses to Yellow Rails, and there is uncertainty regarding the future dynamics of the enormous Snow Goose population.
Habitat loss is also a concern regarding the smaller U.S. breeding population. The status of habitat elsewhere in the U.S. is also important because the entire global population migrates through that country. However, the most important limiting factor for Yellow Rails, regardless of where they breed, is habitat loss on the wintering grounds, which has been so extensive that the wintering range may no longer be contiguous. In Texas and elsewhere in the U.S. wintering grounds, the species seems to be largely restricted to a narrow band of coastline, and coastal marshes throughout the Gulf states are threatened. The size of the known wintering range is no more than 7% the size of the breeding range.
The Yellow Rail has concern status in each of the six U.S. states in which it is known to breed. In addition, it is listed as a Migratory Nongame Bird of Special Management Concern, which identifies migratory non-game birds that, without additional conservation action, are likely to become candidates for listing under the U.S. Endangered Species Act.
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