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American crow

January 26, 2023

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. American crows are the New World counterpart to the carrion crow of Europe and the hooded crow of Eurasia; they all occupy the same ecological niche. Although the American crow and the hooded crow are very similar in size, structure and behavior, their calls and visual appearance are different.

American crow
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Corvidae
Genus: Corvus
Species:
C. brachyrhynchos
Binomial name
Corvus brachyrhynchos
Brehm, 1822
Global range
Pair of crows chasing away a red-tailed hawk from their nest

From beak to tail, an American crow measures 40–50 cm (16–20 in), almost half of which is tail. Mass varies from about 300 to 600 g (11 to 21 oz), with males tending to be larger than females. Plumage is all black, with iridescent feathers. It looks much like other all-black corvids. They are very intelligent, and adaptable to human environments. The most usual call is CaaW!-CaaW!-CaaW!. They can be distinguished from the common raven (C. corax) because American crows are smaller and the beak is slightly less pronounced; from the fish crow (C. ossifragus) because American crows do not hunch and fluff their throat feathers when they call; and from the carrion crow (C. corone) by size, as the carrion crow is larger and of a stockier build.

American crows are common, widespread, and susceptible to the West Nile virus, making them useful as a bioindicator to track the virus's spread. Direct transmission of the virus from crows to humans is impossible. They are considered an agricultural pest, and are subject to hunting and management.

Taxonomy and systematics

The American crow was described by German ornithologist Christian Ludwig Brehm in 1822.[2] Its scientific name means literally 'short-billed crow', from Ancient Greek βραχυ- brachy- ('short-') and ρυνχος rhynchos ('billed').[3]

A 2012 genetic analysis of the genus Corvus by Knud A Jønsson and colleagues using nuclear and mitochondrial DNA calculated that the American crow diverged from a lineage that gave rise to the collared, carrion and hooded crows around 5 million years ago.[4]

"American crow" has been designated the official name by the International Ornithologists' Union (IOC).[5]

Subspecies

 
Northwestern crow range map

The number of subspecies varies by authority, ranging between three and five. The unclear taxonomy of the northwestern crow, previously its own species, has complicated subspecies determinations. Subspecies differ in bill proportion and form a rough NE–SW clinal in size across North America. Birds are smallest in the far west and on the southern coast.[6][2]

  • C. b. brachyrhynchos (Brehm, 1822) – eastern crow: northeastern United States, eastern Canada and surroundings. The nominate subspecies, and largest.
  • C. b. hesperis (Ridgway, 1887) – western crow: western North America except the Arctic north, the Pacific Northwest and the extreme south. Smaller overall with a proportionally more slender bill[7] and low-pitched voice.
  • C. b. caurinus (Baird, 1858) – northwestern crow: of the Pacific temperate rain forests was formerly considered a distinct species as C. caurinus, averaging smaller in size than other American crows with a distinctly hoarser call.[8] It forms a hybrid swarm with American crow (sensu stricto) in coastal Washington and British Columbia.[9] The American Ornithological Society lumped the northwestern crow with the American crow in 2020.[10] It is now considered a geographic variation within C. b. hesperis.[11]
  • C. b. pascuus (Coues, 1899) – Florida crow: Florida. Mid-sized, short-winged, but decidedly long bill and legs.[7]
  • C. b. paulus (Howell, 1913) – southern crow: southern United States. Smaller overall, bill also small.[12]

Description

An American crow making its distinctive call.
 
American crow - Brooklyn, NY
 
The skull of an American crow

The American crow is a large, distinctive bird with iridescent black feathers all over. Its legs, feet and bill are also black. They measure 40–53 cm (16–21 in) in length, of which the tail makes up about 40%. The wing chord is 24.5 to 33 cm (9.6 to 13.0 in), with the wingspan ranging from 85 to 100 cm (33 to 39 in). The bill length can be from 3 to 5.5 cm (1.2 to 2.2 in), varying strongly according to location. The tarsus is 5.5 to 6.5 cm (2.2 to 2.6 in) and the tail is 13.5 to 19 cm (5.3 to 7.5 in).[6] The body mass can vary from 316 to 620 g (11.1 to 21.9 oz). Males tend to be larger than females.[13][14]

 
Brooklyn Museum - American crow - John J. Audubon

The most usual call is a loud, short, and rapid caaw-caaw-caaw. Usually, the birds thrust their heads up and down as they utter this call. American crows can also produce a wide variety of sounds and sometimes mimic noises made by other animals, including other birds such as barred owls.[15]

Visual differentiation from the fish crow (C. ossifragus) is extremely difficult and often inaccurate. Nonetheless, differences apart from size do exist. Fish crows tend to have more slender bills and feet. There may also be a small sharp hook at the end of the fish crow's upper bill. Fish crows also appear as if they have shorter legs when walking. More dramatically, when calling, fish crows tend to hunch and fluff their throat feathers.[citation needed]

If seen flying at a distance from where size estimates are unreliable, the distinctly larger common ravens (C. corax) can be distinguished by their almost lozenge-shaped tail and their larger-looking heads. They also fluff their throat feathers when calling — like fish crows, only more so. Ravens also soar for extended periods, unlike crows, which rarely fly more than a few seconds without flapping their wings.[citation needed]

Crows have been noted to be intelligent. They have the same brain-weight-to-body ratio as humans. This has led to some studies that have identified that crows are self-aware and that young crows take time to learn from tolerant parents. While a human has a neocortex, the crow has a different area in their brain that is equally complex.[16][17]

 
A fledgling, of the Northwestern subtype

The average lifespan of the American crow in the wild is 7–8 years. Captive birds are known to have lived up to 30 years.[18]

Distribution and habitat

The range of the American crow now extends from the Pacific Ocean to the Atlantic Ocean in Canada, on the French islands of Saint-Pierre and Miquelon, south through the United States, and into northern Mexico.[1] The increase in trees throughout the Great Plains during the past century due to fire suppression and tree planting facilitated range expansions of the American crow[19] as well as range expansions of many other species of birds.[20][21][22] Virtually all types of country from wilderness, farmland, parks, open woodland to towns and major cities are inhabited; it is absent only from tundra habitat, where it is replaced by the common raven. This crow is a permanent resident in most of the US, but most Canadian birds migrate some distances southward in winter. Outside of the nesting season these birds often gather in large (thousands or even millions[23]) communal roosts at night.[citation needed]

The American crow was recorded in Bermuda from 1876 onwards.[24]

Behavior and ecology

Studying the behavior of American crows is laborious due to the difficulty in catching them to band them, let alone catching them again. Thus much of their behavior, including daily routine, migration, molting, survivorship, age of first breeding, nestling development, nature of nesting helpers, and more remains poorly studied.[2]

 
American crow
American crow call.
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Diet

 
American crow skeleton (Museum of Osteology)

The American crow is omnivorous. It will feed on invertebrates of all types, carrion, scraps of human food, fruits,[25] nuts such as walnuts and almonds, seeds, eggs and nestlings, stranded fish on the shore and various grains. American crows are active hunters and will prey on mice, young rabbits,[26] frogs, and other small animals. In the winter and autumn, the diet of American crows is more dependent on nuts and acorns. Occasionally, they will visit bird feeders.[27] The American crow is one of only a few species of bird that has been observed modifying and using tools to obtain food.[28]

Like most crows, they will scavenge at landfills, scattering garbage in the process. Where available, corn, wheat and other crops are a favorite food. These habits have historically caused the American crow to be considered a nuisance. However, it is suspected that the harm to crops is offset by the service the American crow provides by eating insect pests.[27]

Reproduction

 
An American crow egg, in the collection of the Children's Museum of Indianapolis

American crows are socially monogamous cooperative breeding birds. Mated pairs form large families of up to 15 individuals from several breeding seasons that remain together for many years.[29] Offspring from a previous nesting season will usually remain with the family to assist in rearing new nestlings. American crows do not reach breeding age for at least two years.[30] Most do not leave the nest to breed for four to five years.[29]

The nesting season starts early, with some birds incubating eggs by early April.[31] American crows build bulky stick nests, nearly always in trees but sometimes also in large bushes and, very rarely, on the ground. They will nest in a wide variety of trees, including large conifers, although oaks are most often used. Three to six eggs are laid and incubated for 18 days. The young are usually fledged by about 36 days after hatching. Predation primarily occurs at the nest site and eggs and nestlings are frequently eaten by snakes, raccoons, ravens and domestic cats. Adults are less frequently predated, but face potential attack from great horned owls, red-tailed hawks, peregrine falcons and eagles. They may be attacked by predators such as coyotes or bobcats at carrion when incautious, although this is even rarer.[27][32]

West Nile virus

American crows succumb easily to West Nile virus infection. This was originally a mosquito-borne African virus causing encephalitis in humans and livestock since about 1000 AD, and was accidentally introduced to North America in 1999, apparently by an infected air traveller who got bitten by a mosquito after arrival. It is estimated that the American crow population has dropped by up to 45% since 1999.[33] Despite this decline, the crow is considered a species of least concern.[34] The disease runs most rampant in the subtropical conditions which encourage reproduction of its mosquito vectors among which Culex tarsalis is most significant. Mortality rates appear to be higher than those in other birds, causing local population losses of up to 72% in a single season.[30][35] Because of this, American crows are a sentinel species indicating the presence of West Nile virus in an area. Crows cannot transmit the virus to humans directly.[18]

Intelligence

American crows, like other corvids, are highly cunning and inquisitive. They are able to steal food from other species, often in creative ways. One example shows a group of crows stealing a fish from a Northern river otter: one bird pecked the otter's tail to distract it while other birds swooped in and stole the fish.[2] They are able to use and modify tools.[36]

Relationship with humans

Crows are a motif in human culture, often associated with death, thieves, graveyards, bad luck, and other negative connotations.[37]

Status and management

The intelligence and adaptability of the American crow has insulated it from threats, and it is instead considered an agricultural pest.[2] In 2012, BirdLife International estimated the American crow population to be around 31 million. The large population and vast range result in the least concern status for the American crow, meaning that the species is not threatened with extinction.[1]

Crows have been killed in large numbers by humans, both for recreation and as part of organized campaigns of extermination.[38] In Canada, American crows have no protections, aside from Quebec which bans their hunting during the nesting season.[2] Laws on their hunting vary throughout the United States. New Jersey allows for a limited hunting season, unless if they are agricultural pests in which case they may be killed. Oklahoma allows hunting even during the nesting season. In the first half of the 20th century, state sponsored campaigns dynamited roosting areas, taking large numbers of crows. A campaign in Oklahoma from 1934 to 1945 dynamited 3.8 million birds. The effect on populations was negligible and damage to agricultural crops did not decrease, and thus the campaign was halted as ineffective. In a study taking data from 1917 to 1999, intentional killings were the overwhelming cause of death for crows, accounting for 68% of all recovered bird bands.[2]

Non-deadly methods of managing crows are varied but usually limited in their effectiveness. High value crops may be netted, but this is cost prohibitive for most other crops. Frightening may be used to disperse crows, including loud noises from guns, fake hawks flown from balloons, fake owls that move with the wind, strips of reflective tape on fences, or recordings of crow distress calls. Poisoned baits are of limited effectiveness, as only the most toxic baits work, and those are generally unacceptable for use. Crows quickly learn to avoid the less-toxic baits, as the baits make crows sick. The actual effect of crows on agriculture has been poorly studied.[2] There is some suggestion that they may be a benefit to farmers, by eating insect pests and chasing off livestock predators like hawks.[37]

References

  1. ^ a b c BirdLife International (2018). "Corvus brachyrhynchos". IUCN Red List of Threatened Species. 2018: e.T22705990A131945410. doi:10.2305/IUCN.UK.2018-2.RLTS.T22705990A131945410.en. Retrieved 19 November 2021.
  2. ^ a b c d e f g h Verbeek, N. A.; Caffrey, Carolee (August 2021). Poole, A. F.; Gill, F. B. (eds.). "American Crow (Corvus brachyrhynchos) version 1.1". Birds of the World. Cornell Lab of Ornithology. doi:10.2173/bow.amecro.01.1. S2CID 241865621.
  3. ^ Liddell, Henry George; Scott, Robert; Stuart-Jones, Henry and McKenzie, Roderick: (1980): A Greek-English Lexicon (abridged ed.). Oxford University Press, Oxford, UK. ISBN 0-19-910207-4.
  4. ^ Jønsson, Knud A.; Fabre, Pierre-Henri; Irestedt, Martin (2012). "Brains, tools, innovation and biogeography in crows and ravens". BMC Evolutionary Biology. 12: 72. doi:10.1186/1471-2148-12-72. PMC 3480872. PMID 22642364.
  5. ^ Gill, Frank; Donsker, David, eds. (2021). "Crows, mudnesters, melampittas, Ifrit, birds-of-paradise". World Bird List Version 11.2. International Ornithologists' Union. Retrieved 26 October 2021.
  6. ^ a b Madge, Steve & Burn, Hilary (1994): Crows and jays: a guide to the crows, jays and magpies of the world. A&C Black, London. ISBN 0-7136-3999-7.
  7. ^ a b Goodwin & Gillmor (1976): p. 87
  8. ^ Dick, Gary Owen (2007): American Crow. Whatbird.com – Field Guide to Birds of North America. identify.whatbird.com/obj/103/_/American_Crow.aspx Retrieved 2007-October-18.
  9. ^ 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. PMID 32034818. S2CID 211064373.
  10. ^ 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.
  11. ^ "Corvus brachyrhynchos hesperis (caurinus or occidentalis) (American Crow (caurinus or occidentalis)) - Avibase". avibase.bsc-eoc.org. Retrieved 2021-10-19.
  12. ^ Goodwin & Gillmor (1976) p. 88.
  13. ^ Kilham, Lawrence. The American Crow and the Common Raven. p. 52
  14. ^ American Crow, Life History, All About Birds – Cornell Lab of Ornithology. Allaboutbirds.org. Retrieved on 2013-03-06.
  15. ^ Lawrence Kilham (October 1990). The American Crow and the Common Raven. Texas A&M University Press. pp. 62–. ISBN 978-0-89096-466-8.
  16. ^ Amanda Heidt. "Like humans, these big-brained birds may owe their smarts to long childhoods".
  17. ^ Chris Baraniuk. "Crows have long been considered cunning. But their intelligence may be far more advanced than we ever thought possible".
  18. ^ a b Connecticut Department of Environmental Protection (2001): American Crow Fact Sheet November 5, 2006, at the Wayback Machine. Version of 2001. Retrieved 2006-October-25.
  19. ^ Houston S. 1977. Changing patterns of Corvidae on the prairies. Blue Jay 35:149–155.
  20. ^ Livezey KB. 2009a. Range expansion of Barred Owls, part I: chronology and distribution. American Midland Naturalist 161:49–56.
  21. ^ Livezey KB. 2009b. Range expansion of Barred Owls, part 2: facilitating ecological changes. American Midland Naturalist 161:323–349.
  22. ^ Livezey KB. 2010. Killing barred owls to help spotted owls II: implications for many other range-expanding species. Northwestern Naturalist 91:251–270.
  23. ^ Di Dilvestro, Roger. "Something To Crow About". National Wildlife Federation.
  24. ^ Long, John L. (1981). Introduced Birds of the World: The worldwide history, distribution and influence of birds introduced to new environments. Terrey Hills, Sydney: Reed. p. 354. ISBN 0-589-50260-3.
  25. ^ "Corvus brachyrhynchos (American crow)".
  26. ^ "Corvus brachyrhynchos (American crow)".
  27. ^ a b c C. Parr (2005). "Corvus brachyrhynchos". Animal Diversity Web. Retrieved 13 September 2015.
  28. ^ Caffrey, Carolee (2000). "Tool Modification and Use by an American Crow". Wilson Bull. 112 (2): 283–284. doi:10.1676/0043-5643(2000)112[0283:TMAUBA]2.0.CO;2. S2CID 86124230.
  29. ^ a b Roger Segelken: Tree-climbing researcher knows exactly how far the crow flies September 16, 2006, at the Wayback Machine Cornell Chronicle. Retrieved 2006-October-25,
  30. ^ a b Cornell Lab of Ornithology (2002): Bird Guide – American Crow. Retrieved 2006-October-24.
  31. ^ Henninger, W.F. (1906). "A preliminary list of the birds of Seneca County, Ohio" (PDF). Wilson Bulletin. 18 (2): 47–60.
  32. ^ Johnson, Ron American Crows 2017-07-16 at the Wayback Machine. Internet Center for Wildlife Damage Management
  33. ^ LaDeau, Shannon L.; Kilpatrick, A. Marm; Marra, Peter P. (2007). "West Nile virus emergence and large-scale declines of North American bird populations". Nature. 447 (7145): 710–713. Bibcode:2007Natur.447..710L. doi:10.1038/nature05829. PMID 17507930. S2CID 4337661.
  34. ^ Deen, David (December 12, 2012). "The crow – a sociable bird with a long memory". The Chronicle. Barton, Vermont. p. 34.
  35. ^ Caffrey, Carolee; Smith, Shauna C.R.; Weston, Tiffany J. (2005). "West Nile Virus Devastates an American Crow Population". Condor. 107 (1): 128–132. doi:10.1650/7646. S2CID 85419982.
  36. ^ Caffrey, Carolee (June 2000). "Tool Modification and Use by an American Crow". The Wilson Bulletin. 112 (2): 283–284. doi:10.1676/0043-5643(2000)112[0283:TMAUBA]2.0.CO;2. ISSN 0043-5643. S2CID 86124230.
  37. ^ a b Sullivan, Emily. "The Glorious American Crow - Romanticism at SU". from the original on 2020-09-28. Retrieved 2021-10-23.
  38. ^ Campbell, Robert Wayne & Canadian Wildlife Service (1997). "American Crow". The Birds of British Columbia: Passerines : flycatchers through vireos. UBC Press. p. 227. ISBN 978-0-7748-0572-8.

Bibliography

  • Goodwin, Derek & Gillmor, Robert (1976): Crows of the World (1st ed.). University of Washington Press, Seattle.

External links

 
Wikimedia Commons has media related to Corvus brachyrhynchos.
 
Wikispecies has information related to Corvus brachyrhynchos.

January 26, 2023
american, crow, corvus, brachyrhynchos, large, passerine, bird, species, family, corvidae, common, bird, found, throughout, much, north, america, world, counterpart, carrion, crow, europe, hooded, crow, eurasia, they, occupy, same, ecological, niche, although,. 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 American crows are the New World counterpart to the carrion crow of Europe and the hooded crow of Eurasia they all occupy the same ecological niche Although the American crow and the hooded crow are very similar in size structure and behavior their calls and visual appearance are different American crow source source Conservation statusLeast Concern IUCN 3 1 1 Scientific classificationKingdom AnimaliaPhylum ChordataClass AvesOrder PasseriformesFamily CorvidaeGenus CorvusSpecies C brachyrhynchosBinomial nameCorvus brachyrhynchosBrehm 1822Global rangePair of crows chasing away a red tailed hawk from their nest From beak to tail an American crow measures 40 50 cm 16 20 in almost half of which is tail Mass varies from about 300 to 600 g 11 to 21 oz with males tending to be larger than females Plumage is all black with iridescent feathers It looks much like other all black corvids They are very intelligent and adaptable to human environments The most usual call is CaaW CaaW CaaW They can be distinguished from the common raven C corax because American crows are smaller and the beak is slightly less pronounced from the fish crow C ossifragus because American crows do not hunch and fluff their throat feathers when they call and from the carrion crow C corone by size as the carrion crow is larger and of a stockier build American crows are common widespread and susceptible to the West Nile virus making them useful as a bioindicator to track the virus s spread Direct transmission of the virus from crows to humans is impossible They are considered an agricultural pest and are subject to hunting and management Contents 1 Taxonomy and systematics 1 1 Subspecies 2 Description 3 Distribution and habitat 4 Behavior and ecology 4 1 Diet 4 2 Reproduction 4 3 West Nile virus 4 4 Intelligence 5 Relationship with humans 6 Status and management 7 References 8 Bibliography 9 External linksTaxonomy and systematics EditThe American crow was described by German ornithologist Christian Ludwig Brehm in 1822 2 Its scientific name means literally short billed crow from Ancient Greek braxy brachy short and rynxos rhynchos billed 3 A 2012 genetic analysis of the genus Corvus by Knud A Jonsson and colleagues using nuclear and mitochondrial DNA calculated that the American crow diverged from a lineage that gave rise to the collared carrion and hooded crows around 5 million years ago 4 American crow has been designated the official name by the International Ornithologists Union IOC 5 Subspecies Edit Northwestern crow range map The number of subspecies varies by authority ranging between three and five The unclear taxonomy of the northwestern crow previously its own species has complicated subspecies determinations Subspecies differ in bill proportion and form a rough NE SW clinal in size across North America Birds are smallest in the far west and on the southern coast 6 2 C b brachyrhynchos Brehm 1822 eastern crow northeastern United States eastern Canada and surroundings The nominate subspecies and largest C b hesperis Ridgway 1887 western crow western North America except the Arctic north the Pacific Northwest and the extreme south Smaller overall with a proportionally more slender bill 7 and low pitched voice C b caurinus Baird 1858 northwestern crow of the Pacific temperate rain forests was formerly considered a distinct species as C caurinus averaging smaller in size than other American crows with a distinctly hoarser call 8 It forms a hybrid swarm with American crow sensu stricto in coastal Washington and British Columbia 9 The American Ornithological Society lumped the northwestern crow with the American crow in 2020 10 It is now considered a geographic variation within C b hesperis 11 C b pascuus Coues 1899 Florida crow Florida Mid sized short winged but decidedly long bill and legs 7 C b paulus Howell 1913 southern crow southern United States Smaller overall bill also small 12 Description Edit source source source source source source source source source source source source source source An American crow making its distinctive call American crow Brooklyn NY The skull of an American crow The American crow is a large distinctive bird with iridescent black feathers all over Its legs feet and bill are also black They measure 40 53 cm 16 21 in in length of which the tail makes up about 40 The wing chord is 24 5 to 33 cm 9 6 to 13 0 in with the wingspan ranging from 85 to 100 cm 33 to 39 in The bill length can be from 3 to 5 5 cm 1 2 to 2 2 in varying strongly according to location The tarsus is 5 5 to 6 5 cm 2 2 to 2 6 in and the tail is 13 5 to 19 cm 5 3 to 7 5 in 6 The body mass can vary from 316 to 620 g 11 1 to 21 9 oz Males tend to be larger than females 13 14 Brooklyn Museum American crow John J Audubon The most usual call is a loud short and rapid caaw caaw caaw Usually the birds thrust their heads up and down as they utter this call American crows can also produce a wide variety of sounds and sometimes mimic noises made by other animals including other birds such as barred owls 15 Visual differentiation from the fish crow C ossifragus is extremely difficult and often inaccurate Nonetheless differences apart from size do exist Fish crows tend to have more slender bills and feet There may also be a small sharp hook at the end of the fish crow s upper bill Fish crows also appear as if they have shorter legs when walking More dramatically when calling fish crows tend to hunch and fluff their throat feathers citation needed If seen flying at a distance from where size estimates are unreliable the distinctly larger common ravens C corax can be distinguished by their almost lozenge shaped tail and their larger looking heads They also fluff their throat feathers when calling like fish crows only more so Ravens also soar for extended periods unlike crows which rarely fly more than a few seconds without flapping their wings citation needed Crows have been noted to be intelligent They have the same brain weight to body ratio as humans This has led to some studies that have identified that crows are self aware and that young crows take time to learn from tolerant parents While a human has a neocortex the crow has a different area in their brain that is equally complex 16 17 A fledgling of the Northwestern subtype The average lifespan of the American crow in the wild is 7 8 years Captive birds are known to have lived up to 30 years 18 Distribution and habitat EditThe range of the American crow now extends from the Pacific Ocean to the Atlantic Ocean in Canada on the French islands of Saint Pierre and Miquelon south through the United States and into northern Mexico 1 The increase in trees throughout the Great Plains during the past century due to fire suppression and tree planting facilitated range expansions of the American crow 19 as well as range expansions of many other species of birds 20 21 22 Virtually all types of country from wilderness farmland parks open woodland to towns and major cities are inhabited it is absent only from tundra habitat where it is replaced by the common raven This crow is a permanent resident in most of the US but most Canadian birds migrate some distances southward in winter Outside of the nesting season these birds often gather in large thousands or even millions 23 communal roosts at night citation needed The American crow was recorded in Bermuda from 1876 onwards 24 Behavior and ecology EditStudying the behavior of American crows is laborious due to the difficulty in catching them to band them let alone catching them again Thus much of their behavior including daily routine migration molting survivorship age of first breeding nestling development nature of nesting helpers and more remains poorly studied 2 American crow source source American crow call Problems playing this file See media help Diet Edit American crow skeleton Museum of Osteology The American crow is omnivorous It will feed on invertebrates of all types carrion scraps of human food fruits 25 nuts such as walnuts and almonds seeds eggs and nestlings stranded fish on the shore and various grains American crows are active hunters and will prey on mice young rabbits 26 frogs and other small animals In the winter and autumn the diet of American crows is more dependent on nuts and acorns Occasionally they will visit bird feeders 27 The American crow is one of only a few species of bird that has been observed modifying and using tools to obtain food 28 Like most crows they will scavenge at landfills scattering garbage in the process Where available corn wheat and other crops are a favorite food These habits have historically caused the American crow to be considered a nuisance However it is suspected that the harm to crops is offset by the service the American crow provides by eating insect pests 27 Reproduction Edit An American crow egg in the collection of the Children s Museum of Indianapolis American crows are socially monogamous cooperative breeding birds Mated pairs form large families of up to 15 individuals from several breeding seasons that remain together for many years 29 Offspring from a previous nesting season will usually remain with the family to assist in rearing new nestlings American crows do not reach breeding age for at least two years 30 Most do not leave the nest to breed for four to five years 29 The nesting season starts early with some birds incubating eggs by early April 31 American crows build bulky stick nests nearly always in trees but sometimes also in large bushes and very rarely on the ground They will nest in a wide variety of trees including large conifers although oaks are most often used Three to six eggs are laid and incubated for 18 days The young are usually fledged by about 36 days after hatching Predation primarily occurs at the nest site and eggs and nestlings are frequently eaten by snakes raccoons ravens and domestic cats Adults are less frequently predated but face potential attack from great horned owls red tailed hawks peregrine falcons and eagles They may be attacked by predators such as coyotes or bobcats at carrion when incautious although this is even rarer 27 32 West Nile virus Edit American crows succumb easily to West Nile virus infection This was originally a mosquito borne African virus causing encephalitis in humans and livestock since about 1000 AD and was accidentally introduced to North America in 1999 apparently by an infected air traveller who got bitten by a mosquito after arrival It is estimated that the American crow population has dropped by up to 45 since 1999 33 Despite this decline the crow is considered a species of least concern 34 The disease runs most rampant in the subtropical conditions which encourage reproduction of its mosquito vectors among which Culex tarsalis is most significant Mortality rates appear to be higher than those in other birds causing local population losses of up to 72 in a single season 30 35 Because of this American crows are a sentinel species indicating the presence of West Nile virus in an area Crows cannot transmit the virus to humans directly 18 Intelligence Edit American crows like other corvids are highly cunning and inquisitive They are able to steal food from other species often in creative ways One example shows a group of crows stealing a fish from a Northern river otter one bird pecked the otter s tail to distract it while other birds swooped in and stole the fish 2 They are able to use and modify tools 36 Relationship with humans EditCrows are a motif in human culture often associated with death thieves graveyards bad luck and other negative connotations 37 Status and management EditThe intelligence and adaptability of the American crow has insulated it from threats and it is instead considered an agricultural pest 2 In 2012 BirdLife International estimated the American crow population to be around 31 million The large population and vast range result in the least concern status for the American crow meaning that the species is not threatened with extinction 1 Crows have been killed in large numbers by humans both for recreation and as part of organized campaigns of extermination 38 In Canada American crows have no protections aside from Quebec which bans their hunting during the nesting season 2 Laws on their hunting vary throughout the United States New Jersey allows for a limited hunting season unless if they are agricultural pests in which case they may be killed Oklahoma allows hunting even during the nesting season In the first half of the 20th century state sponsored campaigns dynamited roosting areas taking large numbers of crows A campaign in Oklahoma from 1934 to 1945 dynamited 3 8 million birds The effect on populations was negligible and damage to agricultural crops did not decrease and thus the campaign was halted as ineffective In a study taking data from 1917 to 1999 intentional killings were the overwhelming cause of death for crows accounting for 68 of all recovered bird bands 2 Non deadly methods of managing crows are varied but usually limited in their effectiveness High value crops may be netted but this is cost prohibitive for most other crops Frightening may be used to disperse crows including loud noises from guns fake hawks flown from balloons fake owls that move with the wind strips of reflective tape on fences or recordings of crow distress calls Poisoned baits are of limited effectiveness as only the most toxic baits work and those are generally unacceptable for use Crows quickly learn to avoid the less toxic baits as the baits make crows sick The actual effect of crows on agriculture has been poorly studied 2 There is some suggestion that they may be a benefit to farmers by eating insect pests and chasing off livestock predators like hawks 37 References Edit a b c BirdLife International 2018 Corvus brachyrhynchos IUCN Red List of Threatened Species 2018 e T22705990A131945410 doi 10 2305 IUCN UK 2018 2 RLTS T22705990A131945410 en Retrieved 19 November 2021 a b c d e f g h Verbeek N A Caffrey Carolee August 2021 Poole A F Gill F B eds American Crow Corvus brachyrhynchos version 1 1 Birds of the World Cornell Lab of Ornithology doi 10 2173 bow amecro 01 1 S2CID 241865621 Liddell Henry George Scott Robert Stuart Jones Henry and McKenzie Roderick 1980 A Greek English Lexicon abridged ed Oxford University Press Oxford UK ISBN 0 19 910207 4 Jonsson Knud A Fabre Pierre Henri Irestedt Martin 2012 Brains tools innovation and biogeography in crows and ravens BMC Evolutionary Biology 12 72 doi 10 1186 1471 2148 12 72 PMC 3480872 PMID 22642364 Gill Frank Donsker David eds 2021 Crows mudnesters melampittas Ifrit birds of paradise World Bird List Version 11 2 International Ornithologists Union Retrieved 26 October 2021 a b Madge Steve amp Burn Hilary 1994 Crows and jays a guide to the crows jays and magpies of the world A amp C Black London ISBN 0 7136 3999 7 a b Goodwin amp Gillmor 1976 p 87 Dick Gary Owen 2007 American Crow Whatbird com Field Guide to Birds of North America identify whatbird com obj 103 American Crow aspx Retrieved 2007 October 18 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 PMID 32034818 S2CID 211064373 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 Corvus brachyrhynchos hesperis caurinus or occidentalis American Crow caurinus or occidentalis Avibase avibase bsc eoc org Retrieved 2021 10 19 Goodwin amp Gillmor 1976 p 88 Kilham Lawrence The American Crow and the Common Raven p 52 American Crow Life History All About Birds Cornell Lab of Ornithology Allaboutbirds org Retrieved on 2013 03 06 Lawrence Kilham October 1990 The American Crow and the Common Raven Texas A amp M University Press pp 62 ISBN 978 0 89096 466 8 Amanda Heidt Like humans these big brained birds may owe their smarts to long childhoods Chris Baraniuk Crows have long been considered cunning But their intelligence may be far more advanced than we ever thought possible a b Connecticut Department of Environmental Protection 2001 American Crow Fact Sheet Archived November 5 2006 at the Wayback Machine Version of 2001 Retrieved 2006 October 25 Houston S 1977 Changing patterns of Corvidae on the prairies Blue Jay 35 149 155 Livezey KB 2009a Range expansion of Barred Owls part I chronology and distribution American Midland Naturalist 161 49 56 Livezey KB 2009b Range expansion of Barred Owls part 2 facilitating ecological changes American Midland Naturalist 161 323 349 Livezey KB 2010 Killing barred owls to help spotted owls II implications for many other range expanding species Northwestern Naturalist 91 251 270 Di Dilvestro Roger Something To Crow About National Wildlife Federation Long John L 1981 Introduced Birds of the World The worldwide history distribution and influence of birds introduced to new environments Terrey Hills Sydney Reed p 354 ISBN 0 589 50260 3 Corvus brachyrhynchos American crow Corvus brachyrhynchos American crow a b c C Parr 2005 Corvus brachyrhynchos Animal Diversity Web Retrieved 13 September 2015 Caffrey Carolee 2000 Tool Modification and Use by an American Crow Wilson Bull 112 2 283 284 doi 10 1676 0043 5643 2000 112 0283 TMAUBA 2 0 CO 2 S2CID 86124230 a b Roger Segelken Tree climbing researcher knows exactly how far the crow flies Archived September 16 2006 at the Wayback Machine Cornell Chronicle Retrieved 2006 October 25 a b Cornell Lab of Ornithology 2002 Bird Guide American Crow Retrieved 2006 October 24 Henninger W F 1906 A preliminary list of the birds of Seneca County Ohio PDF Wilson Bulletin 18 2 47 60 Johnson Ron American Crows Archived 2017 07 16 at the Wayback Machine Internet Center for Wildlife Damage Management LaDeau Shannon L Kilpatrick A Marm Marra Peter P 2007 West Nile virus emergence and large scale declines of North American bird populations Nature 447 7145 710 713 Bibcode 2007Natur 447 710L doi 10 1038 nature05829 PMID 17507930 S2CID 4337661 Deen David December 12 2012 The crow a sociable bird with a long memory The Chronicle Barton Vermont p 34 Caffrey Carolee Smith Shauna C R Weston Tiffany J 2005 West Nile Virus Devastates an American Crow Population Condor 107 1 128 132 doi 10 1650 7646 S2CID 85419982 Caffrey Carolee June 2000 Tool Modification and Use by an American Crow The Wilson Bulletin 112 2 283 284 doi 10 1676 0043 5643 2000 112 0283 TMAUBA 2 0 CO 2 ISSN 0043 5643 S2CID 86124230 a b Sullivan Emily The Glorious American Crow Romanticism at SU Archived from the original on 2020 09 28 Retrieved 2021 10 23 Campbell Robert Wayne amp Canadian Wildlife Service 1997 American Crow The Birds of British Columbia Passerines flycatchers through vireos UBC Press p 227 ISBN 978 0 7748 0572 8 Bibliography EditGoodwin Derek amp Gillmor Robert 1976 Crows of the World 1st ed University of Washington Press Seattle External links Edit Wikimedia Commons has media related to Corvus brachyrhynchos Wikispecies has information related to Corvus brachyrhynchos Skull of American Crow Pictures of American Crow on Birds of the World at Flickr American Crow media Internet Bird Collection American crow at the Encyclopedia of Life American Crow call American Crow photo gallery at VIREO Drexel University Northwestern Crow call two birds Retrieved from https en wikipedia org w index php title American crow amp oldid 1123285230, wikipedia, wiki, 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