C. b. caurinus
|Corvus brachyrhynchos caurinus|
|Northwestern crow range|
The northwestern crow (Corvus brachyrhynchos caurinus) is an all-black passerine bird of the crow genus native to the northwest of North America. It is a clinal variant or subspecies of the American crow (Corvus brachyrhynchos), but it averages slightly smaller (33–41 cm in length) than other subspecies. With the exception of calls, this taxon is almost impossible to identify in the field, and is largely identified by range.
This taxon was described by Spencer Fullerton Baird in 1858. The American Ornithologists' Union considers it a subspecies of the American crow. It forms a hybrid swarm with American crow (sensu stricto) in coastal Washington and British Columbia.
“Northwestern Crows were originally described based on size, being smaller than the American Crow, and behavior, but over the years the people who’ve looked at specimens or observed birds in the field have mostly come to the conclusion that the differences are inconsistent. Now the genomic data have indicated that this is really variation within a species, rather than two distinct species.” - Terry Chesser, chair of the American Ornithological Society North American Checklist Committee.
This subspecies' plumage is virtually identical to that of the American crow (sensu stricto), but averages smaller in size. Like the American crow (sensu stricto), the sexes look the same. Older birds in breeding condition may be reliably sexed by in-hand criteria such as cloacal protuberance (male) or by brood patch (female). Younger birds may not attain breeding condition as they assist at the nest.
Distribution and habitat
This subspecies occurs in coastal regions and offshore islands of southern Alaska, south through British Columbia to Washington. Beaches and shorelines are the principal forage areas. It can often be seen in and around urban areas.
Very similar to that of the fish crow; the northwestern crow eats stranded fish, shellfish, crabs and mussels, and also searches through refuse containers for suitable food items. It has been seen to fly into the air with mussels and drop them onto hard surfaces to break them open. It also regularly eats insects, other invertebrates, and various fruits (especially berries). It raids other birds' nests to eat eggs and hatchlings.
Generally solitary, but sometimes built in association with a few other individuals in small, loose colonies in trees or sometimes large bushes. Very rarely, it will nest on cliffs in a recess or even on the ground in a remote area if overhung by a rock for shelter. It is a typical crow nest with 4-5 eggs usually laid.
The voice is very varied, and many types of call are made, but the most common are usually described as a high pitched "caw" and the sound of a cork coming out of a bottle. A "wok-wok-wok" is given by a bird in flight if straggling behind the group, and various clicks and mechanical sounding rattles are also heard.
Advisory sign during nesting season of Northwestern Crow, Sidney, British Columbia
- BirdLife International (2012). "Corvus caurinus". IUCN Red List of Threatened Species. 2012. Retrieved 26 November 2013.old-form url
- American Ornithologists' Union. (1983) Check-list of North American Birds. 7th Edition.
- Chesser, R Terry; Billerman, Shawn M; Burns, Kevin J; Cicero, Carla; Dunn, Jon L; Kratter, Andrew W; Lovette, Irby J; Mason, Nicholas A; Rasmussen, Pamela C; Remsen, J V; Stotz, Douglas F (2020-07-24). "Sixty-first Supplement to the American Ornithological Society's Check-list of North American Birds". The Auk. 137 (3): ukaa030. doi:10.1093/auk/ukaa030. ISSN 0004-8038.
- Slager, David L.; Epperly, Kevin L.; Ha, Renee R.; Rohwer, Sievert; Wood, Chris; Hemert, Caroline; Klicka, John (2020). "Cryptic and extensive hybridization between ancient lineages of American crows". Molecular Ecology. 29 (5): 956–969. doi:10.1111/mec.15377. ISSN 0962-1083.
- "Goodbye Northwestern Crow, Hello Mexican Duck". American Ornithological Society. 2020-06-30. Retrieved 2020-09-08.
- National Geographic Society. 1983. Field Guide to the birds of North America.
- Walking on the ground
- Perching on a rail
- Urban bird walking on pavement
- Skull of Northwestern Crow
- Northwestern Crow photo gallery
- Corvus caurinus videos on the Internet Bird Collection