omnivorous

Hallmarks of a CORVID

| bindyamc
house crow painting

Corvids can move considerable distances in response to temporal and spatial variation in food availability.4 .They are mainly omnivorous. The increase in available anthropogenic food sources is contributing to population increase in some corvid species.5Some corvids are predators of other birds.During the wintering months corvids typically form foraging flocks.24 Some crows eat agricultural pests- cutworms, wireforms, grasshoppers, harmful weeds.6.Caching, or hiding, food items for later consumption is widespread among birds and mammals7 , and in the corvid family in particular8 . They feed largely on refuse around human habitations, small reptiles and mammals9 . Some birds, including tits Paridae and crows Corvidae, are known to store food such as seeds and acorns for later consumption10 Crows also store man-made foods such as bread, meat and fried eggs 11 .

THE TRUTH BEHIND FABLES– Corvids have often featured in tales. Aesop’s fable ‘the crow and the pitcher’ more fact than fiction.  In Aesop’s fable ‘The crow and the pitcher’ a thirsty crow uses stones to raise the level of water in a pitcher to quench its thirst. The scientists recently published their results in PLOS One.

Project Gutenberg etext 19994, http://www.gutenberg.org/etext/19994 / Public domain

They display remarkable intelligence for animals of their size and are among the most intelligent birds thus far studied.12 Their total brain- to – body mass ratio is equal to that of non human great Apes and cetaceans, and only slightly lower than that of humans .13 Young ravens, Corvus corax, have a predisposition to move objects around with their beaks, press them visibly towards large objects and then also to insert them into crevices and ultimately to cover them.14 Because of their extraordinary cognitive abilities, they are often associated with heavenly bodies and divinities, i.e. the Raven (Corvus corax) being the bird of Apollo and Odin. In many cultures, corvids and their shiny plumage are symbols for the sun and happiness 15 . One carrion crow was documented to crack nuts by placing them on a cross walk, letting the passing cars crack the shell, waiting for the light to turn red, and then safely retrieving the contents16 .

Self Recognition Ability in Crows: ” A circular colored mark was inconspicuously placed on the throat under the bill where crows could see it only from its mirror-reflected image; a similar black mark placed at identical location which was difficult to be seen served as the control condition. Crows exhibited greater preference in response to the mark when in front of the mirror, compared to they were in front of the non-reflective black cardboard. The majority (4/6) crows responded to the mirror-reflected self-image, as evidenced by attempts to remove the coloured mark by using beak or claws; no such response was found in control condition. These results suggest self-recognition by Indian house crows.” (Buniyaadi, A., Taufique, S.K.T. & Kumar, V.)17

Crows can recognize People’s faces– It was demonstrated by the scientists experimentally that a cognitively advanced, social bird, the American crow, Corvus brachyrhynchos, quickly and accurately learns to recognize the face of a dangerous person and continues to do so for at least 2.7 years.18 Wildlife experts John Marzluff and Tony Angell expose crow intelligence in their 2012 book, Gifts of the Crows, writing “Corvids assume characteristics that were once ascribed only to humans, including self-recognition, insight, revenge, tool use, mental time travel, deceit, murder, language, play, calculated risk taking, social learning, and traditions. We are different, but by a degree.” Marzluff also led research which found crows can even recognize human faces.19

An Indian man has been attacked every day for the past three years by crows ‘bent on vengeance’ after one of their chicks died in his hands.Shiva Kewat, from Madhya Pradesh, India, said he tried to save the baby bird after it got stuck in iron netting but the chick didn’t make it.The daily wager, who has been repeatedly scratched and pecked, now has to take a stick with him every time he leaves the house in case the birds decide to launch an attack, reports the Times of India.

SOCIAL LIFE -Like most birds, corvids are monogamous, and the core unit is therefore the mated pair. This pair bond is typically for life, and the pair remains together throughout the year. For example, rooks and ravens find a partner during the autumn months, taking part in impressive aerobatic displays and food sharing which may be to assess the quality of a potential mate. Once juvenile rooks and ravens pair, they engage in extensive mutual preening and bill twining (bill holding) and support one another in fights. 21

Roosting– A typical bird behaviour where a group of individuals congregate in an area for a few hours effected by environmental signals and return to the same site with the reappearance of these signals. Larger trees with greater canopy, nearby human habitation which provide them shelter and safety along with anthropogenic feeding opportunities and moderate vegetation patches near the roosting places were the characteristics preferred for roosting purpose by house crows.20 Roosting together allows sharing of information, such as the location of food sources (Marzluff et al. 1996). This is how it looks when crows roost on a tree.

house crow

A House Crow(Corvus splendens)
By J.M.Garg – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=3002441(grooming behaviour)
By J.M.Garg – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2878206 (crows nest)

By J.M.Garg – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2878247 (crow hatchlings)

The Indian crow (Corvus splendens) is black, with a ring of grey feathers around the neck. The beak is arched. The adult bird is about 17 inches long, and the male and female are similar. The Indian crow may be distinguished from the local crow species by the ring of grey feathers around the neck, a more arched beak, and its slightly smaller size. It also has a different call.

Also known as the House crow, Colombo crow and Ceylon crow, the Indian crow Corvus splendens is distributed from southern Iran through India, the Himalayas, Sikkim, Bhutan, East and West Pakistan, Baluchistan, Nepal, Assam, Burma and Ceylon to southern China, and also the Laccadive and Maldive Islands. It has been introduced and established in Malaya and a number of places in eastern and north-eastern Africa, such as Zanzibar and Pemba Islands, Mombasa, Port Sudan and also at Muscat and Aden.23

C. splendens nests mainly in large trees close to human habitation. It pairs for life and is a more or less solitary nester, so several nests may be located in one large tree (Madge and Burn, 1994; Allen and Davies, 2005). The breeding season varies somewhat over the range but usually peaks in March/April to July/August, although in some areas most activity occurs in Oct/Dec. Four to five pale blue-green, brown-speckled eggs are laid in a typical corvid nest of twigs lined with fine material, though wire may be used where twigs are lacking (Ryall, 1990). The Asian koel Eudynamys scolopacea (or E. scolopaceus) is a frequent brood parasite in the native range and Malaysia (Ali and Ripley, 1972; Wells, 2007). Where introduced, C. splendens usually causes local declines of native avifauna as its population builds up, through intensive nest predation of small bird species (especially colonial nesters) and harassment of larger species, and probably through direct competition with other scavengers (Ryall, 1992a). https://www.cabi.org/isc/datasheet/15463

PILFERER– Being omnivorous, it pilfers anything edible, entering houses, hotel rooms and other buildings, in search of food……..In India, it raids crops such as wheat and maize, causes severe damage to fruit in orchards, is a robber of eggs, persecutor of young wild birds and occasionally takes young poultry. 25

Naturalist Candace Savage in her book “Bird Brains” has regarded this expression as obsolete in the light of new research on the family of Corvids

And while the law of competition may be sometimes hard for the individual, it is best for the race, because it ensures the survival of the fittest in every department.

Andrew Carnegie

There’s one more variety of crow seen widely in India- Indian Jungle Crow(Corvus culminatus) about which I will share in my next post. Happy Blogging!

CITATIONS:-

  1. Perrins, Christopher(2003) The New Encyclopedia of Birds, Oxford University Press: Oxford)
  2. Robertson, Don(30 Jan 2000): Bird families of the World:Corvida)
  3. Droege, G., Töpfer, T. The Corvids Literature Database—500 years of ornithological research from a crow’s perspective. Database (2016) Vol. 2016: article ID bav122; doi:10.1093/database/bav122
  4. Marzluff and Neatherlin 2006
  5. Marzluff, John M; Neatherlin, Eric(2006).
  6. Shades of Night: The Aviary Archived, 15 April, 2006,way back Machine
  7. Vander Wall 1990
  8. de Kort & Clayton 2006,“Corvid Response to human settlements and camp grounds: Causes, consequences and challenges for conservation.”Biological Conservation.
  9. Mikula,P; Morelli,F; Lucan, R.K; Jones, D.N; Tryjanowski,P.(2016). “Bats as prey of diurnal birds: a global perspective” Mammal Review. 46(3)
  10. Vander Wall, 1990; Krebs, 1990; Bugnyar & Kotrschal, 2002).
  11. Higuchi & Morishita, 1997; National Science Museum Nature Education Garden, 2002)
  12. Prior,  Helmut;Schwarz,Ariane;Gunturkun,Onur(2008).DeWaal,Frans(ed).”Mirror induced Behaviour in Magpie(Pica pica ).Evidence of self recognition”PLOS Biology.6(8). e 202
  13. Birding in India and South Asia: Corvidae. Blount, WP(1949)
  14. Bugnyar T., Stowe M., Heinrich B.2007aThe ontogeny of caching in ravens, Corvus corax. Anim. Behav. 74, 757–767,(doi:10.1016/j.anbehav.2006.08.019) [Google Scholar] [Ref list]
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  16. Attenborough- Crows in the city” youtube.com.12/2/2007
  17. Self-recognition in corvids: Evidence from the mirror-mark test in Indian house crows (Corvus splendens). J Ornithol 161, 341–350 (2020). https://doi.org/10.1007/s10336-019-01730-2)
  18. Marzluff, John & Walls, Jeff & Cornell, Heather & Withey, John & Craig, David. (2009). Lasting Recognition of Threatening People by Wild American Crows. Animal Behaviour. 699-707. 10.1016/j.anbehav.2009.12.022.
  19. Marzluff John and Tony Angell. 2012. Gifts of the Crow: How Perception, Emotion, and Thought Allow Smart Birds to Behave Like Humans Hardcover. New York. Atria Books.
  20. Shabnam Saiyad, VC Soni and Bhupat Radadia- Roosting site selection by Indian House Crow(Corvus splendens). International Journal of Fauna and Biological Studies, 2017
  21. Current Biology Vol 17 No 16 R652 The social life of corvids Nicola S. Clayton1 and Nathan J. Eme
  22. Nesting site selection of the house crow(Corvus splendens)- Soh MCK,NS Sodhi,RKH Seoh, BW Brook(2002)
  23. Long, John L. (1967) “The Indian crow,” Journal of the Department of Agriculture, Western Australia, Series 4: Vol. 8 : No. 4 , Article 8. Available at: https://researchlibrary.agric.wa.gov.au/journal_agriculture4/vol8/iss4/8
  24. .Robertson, Don(30 Jan 2000): Bird Families of the world.Corvidae.
  25. Long, John L. (1967) “The Indian crow,” Journal of the Department of Agriculture, Western Australia, Series 4:Vol. 8 : No. 4 , Article 8.Available at:  https://researchlibrary.agric.wa.gov.au/journal_agriculture4/vol8/iss4/8
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