The Indian gray hornbill (Ocyceros birostris) is a common hornbill found on the Indian subcontinent. It is mostly arboreal and is commonly sighted in pairs. It has grey feathers all over the body with a light grey or dull white belly. The horn is black or dark grey with a casque extending to the point of curvature of the horn. It is one of the few hornbill species found in urban areas in many cities where they are able to make use of large trees in avenues.

Description

The Indian grey hornbill is a medium-sized hornbill, measuring around in length.

The male has a larger casque on a dark bill, and the culmen and lower mandible are yellowish. The bare skin around the eye is dark in the male, but sometimes pale reddish in females. The female has a more yellowish bill with black on the basal half and on the casque.

The juveniles lack the casque, and the bare skin around the eye is dull orange.

Distribution

The species is found mainly on the plains up to about . It is found from the foothills of the Himalayas southwards, bounded to the west by the Indus system and to the east by the Ganges Delta. It may make local movements in the drier western region. It is found even in cities that have old avenue trees.

Behaviour and ecology

The call is a squealing call somewhat like that of a black kite. The flight is heavy and involves flapping interspersed with glides. They are found in pairs or small groups. While inside the nest, the female moults her flight feathers and incubates the eggs. The male provides the nest inmates with a steady supply of bark pieces to ensure that the excreta is removed from the nest by absorption and adsorption and to help maintain the micro-climate within the nest cavity. The regrowth of the female's feathers coincides with the maturity of the chicks, at which point the nest is broken open.

A study at a nest near Mumbai noted that the key fruiting trees on which the hornbills fed were Streblus asper, Cansjera rheedii, Carissa carandas, Grewia tiliaefolia, Lannea coromandelica, Ficus spp., Sterculia urens and Securinega leucopyrus. They are also known to take molluscs, scorpions, insects, small birds (they have been recorded removing and possibly preying on rose-ringed parakeet chicks) and reptiles in their diet They are known to feed on the fruits of Thevetia peruviana, which are known to be toxic to many vertebrates.

They are almost completely arboreal, but very rarely descend to the ground to pick up fallen fruits, to dust bathe, or to pick up mud pellets to seal the nest cavity during the nesting period. They indulge in various social activities, including bill-grappling and aerial jousting.

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Indian Grey Hornbill I2 IMG 9029.jpg|Individual with a shorter casque, either a juvenile or female

Indian Grey Hornbill I IMG 9017.jpg|At Uttarakhand, India

Indian grey hornbill foraging.jpg|In Janakpur, Nepal

Indian GreyHornbill.JPG|A pair (female right and male at left) at Mohali, Punjab, northern India

Indian Grey Hornbill at twilight.jpg|Indian Grey Hornbill in Pune. Note the casque, and the distinctive tail feathers.

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References

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Kasambe, R., & Pimplapure, A. (2007): Communal foraging of Indian Grey Hornbill Ocyceros birostris on leaves of Ailanthus excelsa tree. Zoos' Print Journal22(12): 2939

Kasambe, R., Charde, P., Tarar, J.L. (2010): Rescue and rehabilitation of Indian Grey Hornbill (Ocyceros birostris) fledgling at Nagpur. Newsletter for Birdwatchers . 50(5):71-71</ref>

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