The American Crow ( Corvus brachyrhynchos )

1. The American Crow(Corvus brachyrhynchos) PatriciaPongratz

2. Classification Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Aves Order: Passeriformes Family: Corvidae Genus: Corvus Species: Corvus brachyrhynchos (Parr, 2005)

3. Evolution • Earliest corvid fossils date back to the mid-Miocene (~17 MYA) in central Asia • Radiated to other continents, including N. America, where the American crow evolved <0.5 MYA (Verbeek & Caffrey, 2002) • Was not common in most of its current range until the introduction of agriculture(Good, 1952; Marzluff, et al., 2001) (Barker et al., 2004)

4. Physical Characteristics • Adults: • All black, glossy feathers • Albino and partly white birds rare • Brown eyes • Not sexually dimorphic • Juveniles: • Grayish-brown • Less glossy feathers • Blue-grey eyes • Pink gape (Verbeek, N. A. & C. Caffrey, 2002)

5. Physical Characteristics • Size: • “Medium-sized” • 43 - 53 cm long (17 - 21”) • 316 – 575 g (~0.7 - 1.3 lbs) • Often confused with the raven (Corvus corax) (Verbeek & Caffrey, 2002)

6. Source: naturemappingfoundation.org/natmap/facts/crow_vs_raven.html Crows vs. Ravens gerritvynphoto.com kennanward.com, 2002 • Larger; similar to hawk • Long, pointed wings • Shaggy throat “hackles” • Wedge-shaped tail • Bigger, curved bill • Soar in flight • Deep croaking • Mostly solitary • Smaller; similar to pigeon • Blunt wing tips • Smooth throat • Fan-shaped tail • Shorter, straighter bill • Silent wing flapping • High pitched “caw” • Rarely found alone

7. Ecosystem & Economic Roles • Negative • Crop damage • Game bird nest predation • Noise & mess during roosting (Parr, 2005) • Positive • Feed on agricultural pests • Game species • Seed dispersal • Carcass decomposition • Sentinel species for indicating West Nile Virus (Good, 1952)

8. Distribution • Common throughout the continental US • Absent in parts of Washington and in dry areas of the west • Common through most of S. Canada • Many migrate south to US during the winter • Colonized Bermuda between 1840-1843 • Likely introduced by man (Verbeek&Caffrey, 2002)

9. Habitat • Wide range of habitats • Prefers open areas with nearby trees and water • Generally avoids large forested areas, though common along forest edges • Uses natural and manmade habitats • Farmland, dumps, parks, golf courses, cemeteries, vacant lots, and along highways and shorelines • Thrive in urban and suburban areas (Verbeek & Caffrey, 2002; Parr, C. 2005)

10. Diet • Opportunistic scavengers • Feed on whatever is most readily available • Plant Matter – majority of diet • Corn, buckwheat, seeds, nuts, grain, fruit • Animal Matter • Insects, larvae, amphibians, reptiles, fish, shellfish, eggs, nestlings, rodents, carrion • Garbage • Pet food (Hering, 1934)

11. Feeding • Foraging • Occurs on the ground • Food often carried off for consumption (Cristol, 2005) • Caching • Less-preferred foods cached • Usually hidden in open fields away from foraging site • Covered with grass, leaves or dirt (Waite, 2009)

12. Reproduction • Pairing • Do not mate until at least 2 years of age • Monogamous • Exceptions: Incapacitation, death, clutch failure • Polygamy may occur • Exhibit little courtship behavior • Allopreening seen in established pairs (Kilham, 1991) • Cooperative breeders • Offspring remain on or return to natal territory to assist parents with nest building and rearing of young • Can stay with family group for 4+ years • Increased fledging success when helpers present (Good, 1952; Chamberlain-Auger et al. 1990)

13. Life Expectancy • Most do not survive past the first year • Survival rates greater in urban environments • Oldest recorded wild crow lived 29.5 years • This record is disputed • Wild crows of 17 years are not unheard of • Oldest captive crow lived 59 years • Average lifespan is 6 - 10 years in wild (Link, 2004) (McGowan, 2010)

14. Observations • Observations taken at two separate graveyards • Time of Day • Observations taken mostly in afternoon and early evening • Techniques • Watched from car or from on foot • Both often ineffective • Distance • Often within a few yards • Some crows more tolerant than others • Conditions • Crows rarely observed while raining or snowing

15. Holy Cross Cemetery • Located on Wright St in Marquette • Setting • Open land bordered by trees • Scattered trees and buildings throughout • Other Species • Squirrels • Deer

16. Park Cemetery • Located on Seventh St in Marquette • Setting • Open land bordered by trees • Scattered trees and buildings throughout • Ponds scattered throughout • Other Species • Geese • Ducks • Squirrels

17. Behavior Patterns • Sweeping • Bill moves back and forth in a sweeping motion • Stabbing • Food items are held beneath one or both feet and pounded with the tip of the bill • Bill Swiping • Each side of the bill is rubbed against a perch • Sentinel Behavior • Visually scanning area while perched above others; certain calls by this bird elicit behavior from the foraging group

18. Sweeping

19. Sweeping • Occurs during foraging • Proximate Cause • Increases food intake and variety • Ultimate Cause • Acquisition of resources for survival

20. Stabbing

21. Stabbing • Occurs when hard or shelled food item is found • Can occur on the ground or on a perch • Proximate Cause • Removal of tough outer layer of food; increases intake of valuable food resource while minimizing the ingestion of the less-valuable shells (Eugene, 1952). Also increases variety of food choices available • Ultimate Cause • Acquisition of resources for survival

22. Bill Swiping Source: http://www.youtube.com/watch?v=OLgtGO-ieG8

23. Bill Swiping • Occurs after foraging • Proximate Cause • Cleaning, shaping & sharpening of bill for resource acquisition (Cuthill, Witter & Clarke, 1990) • May also serve as a displacement behavior (Kilham, 1991) • Ultimate Cause • Survival

24. Sentinel Behavior

25. Sentinel Behavior • Argued that sentinel behavior is not intentional (Kilham, 1991) • Proximate Cause • Protection of group from predators; better use of foraging time • Ultimate Cause • Survival and reproduction

26. Resources • Barker, F. K., A. Cibois, P. Schikler, J. Feinstein & J. Cracraft. (2004). Phylogeny and diversification of the largest avian radiation. PNAS 101(30):11040-11045. Retrieved from http://www.pnas.org/content/101/30/11040. • Chamberlain-Auger, J. A., P. J. Auger & E. G. Strauss. (1990). Breeding biology of American crows. Wilson Bulletin 102(4):615-622. • Cristol, D. A. (2005). Walnut-caching behavior of American crows. Journal of Field Ornithology 76(1):27-32. • Cuthill, I, M. Witter & L. Clarke. (1992). The function of bill-wiping. Animal Behavior 43(1):103-115. • Good, E. E. (1952). The life history of the American crow Corvis brachyrhynchos brehm. (Doctoral dissertation). Retrieved from Ohio State University. • Hering, P. E. (1934). The food of the American crow in central New York state. The Auk 51(4):470-476. • Kilham, L. (1989). The American crow and the common raven. Texas: A & M University Press.

27. Resources • Link, R. (2004). Living with wildlife in the pacific northwest. Washington: University of Washington Press. • Marzluff, J. M., R. Bowman & R. Donnelly. (2001). Avian ecology and conservation in an urbanizing world. Norwell, Massachusetts: Kluwer Academic Publishers. • McGowan, K. J. (2010). Frequently asked questions about crows. Cornell University Laboratory of Ornithology. Retrieved from http://www.birds.cornell.edu/crows. • Parr, C. (2005). "Corvus brachyrhynchos" (On-line), Animal Diversity Web. Accessed November 29, 2011 http://animaldiversity.ummz.umich.edu/site/accounts/information/Corvus_brachyrhynchos.html. • Verbeek, N. A. and C. Caffrey. (2002). American Crow (Corvus brachyrhynchos), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/647. • Waite, R. K. (1985). Food caching and recovery by farmland corvids. Bird Study 32(1):45-49.