Ridgwayralle

Bestimmung

Ridgway's rail (Rallus obsoletus) is a species of bird found principally along the Pacific coast of North America from the San Francisco Bay Area to southern Baja California, as well as in some regions of the Gulf of California. A member of the rail family, Rallidae, it is a large cinnamon-brown rail that lives in brackish tidal marshes and rarely flies. Its name commemorates American ornithologist Robert Ridgway. This species is closely related to the clapper rail, and until recently was considered a subspecies. It has a long, downward curving bill and is grayish brown with a pale chestnut breast and conspicuous whitish rump patch. It is most active nocturnally and crepuscularly.

Taxonomie

Gattung: Rallus; Familie: Rallidae; Ordnung: Gruiformes.

Wissenschaftlicher Name

Rallus obsoletus

Autorität

Ridgway, 1874

Ordnung

Gruiformes

Familie

Rallidae

Gattung

Rallen

Verbreitung und Lebensraum

Ridgway's rail forages along the ecotone between mudflat and higher vegetated zones and in tidal sloughs. Mussels, clams, arthropods, snails, worms and small fish are its preferred foods, which it retrieves by probing and scavenging the surface while walking. The bird will only forage on mudflats or very shallow water where there is taller plant material nearby to provide protection at high tide. At such high tides it may also prey upon mice, and has been known to scavenge dead fish.<p>One of the largest populations of Ridgway's rails is in San Francisco Bay, where a total of about 1100 are resident. In the past, however, its geographic range spanned more than 90% of the range of the San Francisco Bay. Other frequent sightings of this species around the San Francisco Bay include the Napa Sonoma Marsh, Bothin Marsh in Mill Valley, Gallinas Creek in San Rafael, Arrowhead Marsh and Damon Marsh in Oakland, the Palo Alto baylands, Charleston Slough in Mountain View, Seal Slough in San Mateo and Belmont Slough.<p>For cover, Ridgway's rail seeks out emergent wetland dominated by pickleweed and cordgrass, or brackish emergent wetland with those two plants plus bulrush. It is not clear whether it requires any source of fresh water. Although not migratory in coastal wetlands, this species disperses juveniles into freshwater wetlands in late August through October. Ridgway's rail has been observed to forage in or near relatively disturbed areas, leading one to deduce the importance of protecting even numeral marsh areas; for example this species was seen foraging in a small mudflat area within Seal Slough in San Mateo, three miles from the nearest known breeding area in Belmont.

Zugverhalten

Standvogel

Verhalten

Zugverhalten: Standvogel.

Schutzstatus

Bestandstrend: rückläufig.

Bestandstrend

rückläufig