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CROWS
AND RAVENS Corvus spp: Aves, Passeriformes, Corvidae |
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These are large passerine birds in the genus Corvus of
the family Corvidae. Two major groups of birds in Corvus: are crows and ravens, with ravens being
larger. However this depends in which
geographic area the birds are found, and McGowan (2002) noted several ways
whereby ravens and crows are commonly distinguished. Ravens are the larger birds, and normally
have shaggy throat feathers and a larger bill, than the smaller crows. Ravens also are found to soar more than
crows and may do somersaults in flight. In
America ravens have wedged tails whereas crows do not show this form
clearly. In other geographic areas
the term "crow" may refer to other species of Corvus.
The family Corvidae is believed to
have evolved in Australasia, from which it radiated out to North America,
Africa, Europe and Australia. (Barker et al.
2004). Then crows are thought to have left Australasia and
began developing in Asia.
However, the Corvus genus
has within modern times re-entered Australia and produced five species with
one recognized sub-species.
Both crows and ravens are scavengers but may also seek invertebrates
and small vertebrates for food (Goodwin & Gillmor 1977). They are notorious pests of agriculture
when they attack grain fields or repening fruit in orchards. For that reason, farmers have erected
"scare crows" made to appear as humans to frighten them away. Crows demonstrate complex behavioral
characteristics, such as giving a variety of calls or vocalizations. They may also respond to calls of other bird species as well. Crows also show a remarkable intelligence,
they engage in mid air jousting to establish a pecking order, and they can
make tools to search for food (Rincon 2005, von Bayern et al. 2018). Crows have modest linguistic capabilities
and the ability to relay information over long distances, live in complex,
hierarchic societies involving hundreds of individuals with various
"occupations," and have an intense rivalry with the area's less
socially advanced ravens. Wild hooded
crows in Israel have learned to use bread crumbs for bait-fishing (Hasson
2007). The fossil record of crows is poor in
Europe, and the relationship among most prehistoric species is not
clear. Crow and raven-sized forms
existed long ago. Crows were
regularly hunted by humans up to the Iron Age, documenting the evolution of
the modern taxa. American crows are
not well-documented either A surprisingly high number of species
have become extinct after human colonization; the loss of one
prehistoric Caribbean crow could also have been related to the climate
changes in the last Ice Age (Gill 2003). REFERENCES Alexander, G., T. Mann, C. J. Mulhearn, I. C. R. Rowley,
D. Williams & D. Winn. 1967. Activities of foxes and crows in a flock
of lambing ewes. Australian Journal of Experimental Agriculture. 7 (27): 329. Barker, F. K., A. Cibois, P. Schikler,
J. Feinstein & J. Cracraft. 2004. Phylogeny and diversification of the largest avian
radiation. Proceedings of the National Academy of
Sciences. 101 (30): 11040– Blum, C. R.. W. T. Fitch & T. Bugnyar. 2020. Memorial University Libraries
- Proxy Login. Frontiers in Psychology. 11: 581794. Brook, B. W., N. S. Sodhi, M. C. K. Soh & H. C. Lim.
2003. Abundance and Projected Control of Invasive House Crows in
Singapore. Journal of Wildlife Management. 67 (4): 808. Gill, B. J. 2003. Osteometry and
systematics of the extinct New Zealand Ravens (Aves: Corvidae: Corvus).
Journal of Systematic Palaeontology. 1(1): 43-58. Goodwin, D. & R. Gillmor.
1977. Crows of The World.
St. Lucia, Queensland. University of
Queensland Press 1977. Hasson, Oren. 2007.
Bait-fishing in crows. Orenhasson.com,
March 4, 2021. Heinrich, B.
1988. Winter foraging at carcasses
by three sympatric corvids, with emphasis on recruitment by the
raven, Corvus corax. Behavioral Ecology and
Sociobiology. 23 (3):
141–156. Higuchi, Hiroyoshi.
2019. Carrion Crow manipulating water taps for drinking and
bathing. British Birds 112:
167–169. Lim, H. C., N. S. Sodhi, B. W. Brook & M. C. K.
Soh. 2003. Factors determining
the distribution of three invasive bird species in Singapore. Journal
of Tropical Ecology. 19 (6):
685–695. Linnäe, Carl von, & Alwyne Wheeler. 1766. Caroli a Linné
... Systema naturae per regna tria naturae, secundum classes, ordines,
genera, species, cum characteribus, differentiis, synonymis, locis. Tome I. Holmiae: impensis
direct. Laurentii Salvii 1766. McGowan, K. J. 2002.
Frequently asked questions about crows. What is the difference between a crow and a raven?. Kevin J. McGowan home page: Cornell Laboratory of Ornithology
March 4, 2021. Rincon, P. 2005. Crows
and jays top bird IQ scale. British Broadcasting Co. News 2005. Simpson, D. P. 1979. Cassell's
Latin-English, English-Latin dictionary. London: Cassell
1979. Stahler, Daniel; Berund Heinrich &
Douglas Smith. 2002. Common ravens, Corvus corax, preferentially
associate with grey wolves, Canis lupus, as a foraging strategy in winter.
Animal
Behaviour. 64 (2):
283–290. von Bayern, A. M. P., S. Danel, A. M.
I. Auersperg, B. Mioduszewska, & A. Kacelnik. 2018. Compound tool construction by New Caledonian crows. Scientific
Reports, 8(1). Vucetich, John A., Rolf
Peterson & Thomas A. Waite.
2004. Raven scavenging favours group foraging in wolves.
Animal Behaviour. 67 (6):
1117–1126. Winkler, Robert.
2002. Crow Makes Wire Hook to Get Food. National
Geographic Mag. August 2002. Worthy, T. H., & Richard N. Holdaway. 2002. The Lost World
of the Moa: Prehistoric Life of New Zealand. Life of the
past. Bloomington: Indiana University
Press 2002. |
