STUDIES ON BEHAVIOUR OF HOUSE CROW

STUDIES ON BEHAVIOUR OF HOUSE CROW AT KARNAMADHAVPUR, RAHARA

Author : Tanmoy Bhaduri

Department of Zoology, RKMVC College, Rahara, Kolkata-700118.

Abstract: The House Crow (Corvus splendens ; Aves, Passeriformes, Corvidae) also known as the Colombo Crow, is a common bird of the Crow family, that is of Asian origin but now found in many parts of the world, where they arrived assisted by shipping. It is between the Jackdaw and the Carrion Crow in size (40 cm in length) but is relatively slimmer than either. Due to a human population explosion in the areas it inhabits, this species has also proportionately multiplied. Being an opportunistic omnivorous scavanger has enabled it to thrive in such circumstances. The invasive potential for the species is great all over the tropics. It can travel more than 15 km for feeding. Large trees with big crowns are preferred for nesting. House Crow’s nest is always situated near habitations, in fork close to a tall tree-top, or on outer branches, often in banyan or mango trees. Female builds the nest. During the breeding season, it is seen in pairs, but it usually lives in groups of up to 50 birds. It may become aggressive against raptors. Courtship displays consist of mutual preening and bill-rubbing, occasionally followed by rapid copulation. This behaviour occurs in trees. Breeding season is generally from March to July. During breeding season female crow lays 3-5 eggs, of variable size and colour. Its nest is regularly brood-parasitized by Asian Koel. Four subspecies: C. s. splendens, C. s. zugmayeri ( southern Jammu & Kashmir,Punjab and Rajasthan ), C. s. protegatus (coastal areas, Kerala, Sri Lanka and nearby islets) and C. s. maledivicus  (Maldives islands).

Systematic Position:

Phylum : Chordata

          Class : Aves

                   Subclass : Ornithurae

                             Infra class : Neornithes

                                      Super order : Neognathae           

                                                

                                                  Order : Passeriformes

                                                          Family : Corvidae

                                                                   Specimen : Corvus splendens

Four subspecies: C. s. splendens, C. s. zugmayri (southern Jammu & Kashmir, Punjab and Rajasthan), C. s. portegatus (coastal areas, Kerala, Srilanka and nearby islets), C. s. maledivicus (Maldives islands).

·        The House Crow (Corvus splendens), also known as the Colombo Crow, is a common bird of the crow family, that is of Asian origin but now found in many parts of the world, where they arrived assisted by shipping.

·        It is between the Jackdaw and the Carrion Crow in size 40cm in length, but is relatively slimmer than either. The forehead, crown, throat and upper breast of the birds are richly glossed black, while the neck and breast are lighter grey-brown in colour. The wings, tail and legs are black.

·        There are regional variations in the thickness of the bill and the depth of colour in areas of plumage.

·        House Crow has a widespread distribution in southern Asia, being native to Nepal, Bangladesh, India, Pakistan, Sri Lanka, Maldives and Laccadive Islands, South West Thailand and coastal southern Iran. It has been introduced to East Africa around Zanzibar (around 1897) and Port Sudan, and arrived in Australia via ship but has up to now been exterminated. Recently it has made its arrival in Europe, and has been breeding in the Hook of Holland since 1998. An individual of this species has been present in Cork Harbour on the south coast of Ireland since early September 2010. It is associated with human settlements in all of its range, from small villages to large cities. In Singapore, there was a density of 190 birds/km² in 2001 with efforts to suppress the population in planning.

·        It is as yet not established in the New World. This species is able to make use of resources with great flexibility and appears to be associated with humans, and no populations are known to exist independently of humans.

·        House Crow is well named “Scavenger Bird”. It feeds mainly on the ground, but also in trees or buildings. It is often seen near rubbish, slaughter-houses, markets and farmlands, beaches close to fisheries or near touristic complexes. It feeds largely on refuse around human habitations, small reptiles and other animals such as insects and other small invertebrates, bird’s eggs, nestlings, grain, fruits, seeds, nectar, berries, amphibians and fishes.

   ·        House Crow is very vocal. It often calls while flying, a typical monotonous, rather dry “kaaa-kaaa-kaaa”. But it also may utter numerous articulated and expressive nodes. It also has a couple of softer calls when resting or during courtship.

·        When in flight, we can see easily the long tail and the slender wings of the House Crow. It appears entirely dark, because the contrast between grey and black is difficult to see. 

·        It is suspected that paramyxoviruses, such as PMV 1, that causes Newcastle disease, that may be spread by Corvus splendens. Outbreaks in India of Newcastle disease were often preceded by mortality in crows. They have also been found to carry Cryptococcus neoformans, which can cause cryptococcosis in humans.