American Crow
Corvus brachyrhynchos
Summary 5
The American Crow (Corvus brachyrhynchos) is a large passerine bird species of the family Corvidae. It is a common bird found throughout much of North America. In the interior of the continent south of the Arctic, it is referred to as simply the "crow".
Habitat and ecology 6
Systems
- Terrestrial
Associations 7
American crows do not have significant, unique roles in particular ecosystems. They probably serve as seed dispersers as they eat fruit and cache nuts. They scavenge on carcasses which speeds their decomposition.
Ecosystem Impact: disperses seeds; biodegradation
Ecology 8
In southwestern Manitoba, spring-summer home range averaged 2.6 sq km; foraging flights from nest averaged 382 m, with infrequent flights longer than 700 m (Sullivan and Dinsmore 1992).
Behaviour 9
American Crows are highly vocal birds. Unlike most other songbirds, males and females have the same songs. They have a complex system of loud, harsh caws that are often uttered in repetitive rhythmic series. Shorter and sharper caws called "kos" are probably alarm or alert calls. Slightly longer caws are probably used in territorial defense, and patterns of repetition may be matched in what may be considered "countersinging," or exchanges between territorial neighbors. "Double caws," short caws repeated in stereotyped doublets, may serve as a call-to-arms vocalization, alerting family members to territorial intruders. Sometimes pairs or family members coordinate their cawing in a duet or chorus. Harsher cawing is used while mobbing potential predators.
People are less familiar with the large variety of softer calls crows can make. Melodic, highly variable coos accompanied by bowing postures are used among family members, possibly as greetings or other bonding signals. Coos of cage-mates become similar over time; this vocalization may therefore be the basis of the mimicry ability shown by pet crows. Crows also give several kinds of rattles.
Young crows make gargling sounds that eventually turn into adult vocalizations. Yearling crows also "ramble" or run through long sequences of different patterns and rhythms of cawing.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
Sources and Credits
- (c) Anita Gould, some rights reserved (CC BY-NC), uploaded by Anita Gould, http://www.flickr.com/photos/61897811@N00/2470003522
- (c) Walter Siegmund, some rights reserved (CC BY), https://upload.wikimedia.org/wikipedia/commons/2/20/Corvus_brachyrhynchos_30157.JPG
- (c) Walter Siegmund, some rights reserved (CC BY-SA), https://upload.wikimedia.org/wikipedia/commons/c/c2/Corvus_brachyrhynchos_30186.JPG
- (c) DickDaniels (http://carolinabirds.org/), some rights reserved (CC BY-SA), https://upload.wikimedia.org/wikipedia/commons/f/fd/American_Crow_SanDiego_RWD.jpg
- (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Corvus_brachyrhynchos
- (c) International Union for Conservation of Nature and Natural Resources, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/34398037
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/31387601
- (c) NatureServe, some rights reserved (CC BY-NC), http://eol.org/data_objects/28846804
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/31387598
