Northwestern Crow
Encyclopedia
The Northwestern Crow is an all-black passerine
bird
of the crow genus native to the northwest of North America
. It is very similar to the more western forms of the widespread American Crow
(Corvus brachyrhynchos), but it averages slightly smaller (33-41 cm in length) with proportionately smaller feet and a slightly more slender bill. This taxon
is reliably identified by range only.
in 1858. The American Ornithologists' Union
considers it closely related to the American Crow
, and it may be conspecific. Hybrids with American Crow have been reported but not confirmed.
protuberance (male) or by brood patch
(female). Younger birds may not attain breeding condition as they assist at the nest.
, south through British Columbia
to Washington state. Beaches and shorelines are the principal forage areas. It can often be seen in and around urban areas.
; the Northwestern Crow eats stranded fish
, shellfish, crab
s and mussel
s, 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 insect
s, other invertebrate
s, and various fruits (especially berries). It raids other birds' nests to eat eggs and hatchlings. It takes handouts and remembers anyone who discards food. It is known to soak pieces of bread
in water
.
. The crows often gather in large groups to mob these predators.
Sound links
Video links
Passerine
A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...
bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
of the crow genus native to the northwest of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. It is very similar to the more western forms of the widespread American Crow
American Crow
The American Crow is a large passerine bird species of the family Corvidae. It is a common bird found throughout much of North America...
(Corvus brachyrhynchos), but it averages slightly smaller (33-41 cm in length) with proportionately smaller feet and a slightly more slender bill. This taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
is reliably identified by range only.
Taxonomy
This species was described by Spencer Fullerton BairdSpencer Fullerton Baird
Spencer Fullerton Baird was an American ornithologist, ichthyologist and herpetologist. Starting in 1850 he was assistant-secretary and later secretary of the Smithsonian Institution in Washington, D.C...
in 1858. The American Ornithologists' Union
American Ornithologists' Union
The American Ornithologists' Union is an ornithological organization in the USA. Unlike the National Audubon Society, its members are primarily professional ornithologists rather than amateur birders...
considers it closely related to the American Crow
American Crow
The American Crow is a large passerine bird species of the family Corvidae. It is a common bird found throughout much of North America...
, and it may be conspecific. Hybrids with American Crow have been reported but not confirmed.
Description
This species plumage is virtually identical to American Crow. A percentage may be distinguished by in-hand criteria such as smaller wing chord and tail length, shorter tarsus, and smaller bill. Percentages increase when sex of animal is known. Like the American Crow, the sexes look the same. Older birds in breeding condition may be reliably sexed by in-hand criteria such as cloacalCloaca
In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...
protuberance (male) or by brood patch
Brood patch
thumb|250px|Brood patch of [[Sand Martin]]A brood patch is a patch of featherless skin that is visible on the underside of birds during the nesting season. This patch of skin is well supplied with blood vessels at the surface making it possible for the birds to transfer heat to their eggs when...
(female). Younger birds may not attain breeding condition as they assist at the nest.
Distribution and habitat
This species occurs in coastal regions and offshore islands of southern AlaskaAlaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
, south through British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
to Washington state. Beaches and shorelines are the principal forage areas. It can often be seen in and around urban areas.
Diet
Very similar to that of the Fish CrowFish Crow
The Fish Crow is a species of crow that is associated with wetland habitats in the eastern and southeastern United States.-Taxonomy:The Fish Crow was first described by Alexander Wilson in 1812...
; the Northwestern Crow eats stranded fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, shellfish, crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s and mussel
Mussel
The common name mussel is used for members of several families of clams or bivalvia mollusca, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.The...
s, 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 insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s, other invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s, and various fruits (especially berries). It raids other birds' nests to eat eggs and hatchlings. It takes handouts and remembers anyone who discards food. It is known to soak pieces of bread
Bread
Bread is a staple food prepared by cooking a dough of flour and water and often additional ingredients. Doughs are usually baked, but in some cuisines breads are steamed , fried , or baked on an unoiled frying pan . It may be leavened or unleavened...
in water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
.
Predators
An incomplete list includes cats, raccoons, raptors and ravensCommon Raven
The Common Raven , also known as the Northern Raven, is a large, all-black passerine bird. Found across the northern hemisphere, it is the most widely distributed of all corvids...
. The crows often gather in large groups to mob these predators.
Nesting
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.Voice
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.External links
Image links- Walking on the ground
- Perching on a rail
- Urban bird walking on pavement
- Skull of Northwestern Crow
- Northwestern Crow photo gallery
Sound links
Video links
- Corvus caurinus videos on the Internet Bird Collection