LC
Indian Grey Hornbill Ocyceros birostris



Justification

Justification of Red List Category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Population justification
The global population size has not been quantified, but the species is reported to be widespread and often common (del Hoyo et al. 2001).

Trend justification
The population is suspected to be stable in the absence of evidence for any declines or substantial threats.

Distribution and population

The species is found almost throughout the entire Indian subcontinent. It occurs in India, except in the north-eastern part and higher up in the Himalaya, in north-eastern Pakistan, southern Nepal and north-western Bangladesh (Poonswad et al. 2013). The species is widely distributed in the Eastern Ghats of India (Balasubramanian et al. 2005). Important sites include Sathyamangalam Wildlife Sanctuary, Hogenakal, Sri Venkateswara National Park, Sri Lankamalleswara Wildlife Sanctuary,  Gundlabrameshwaram Wildlife Sanctuary, Nagarjuna sagar-Sri Sailam Tiger Reserve and Penusila Narasimha Wildlife Sanctuary (Balasubramanian et al. 2005). It is one of the most-reported hornbill species in India, with many sightings on the citizen science platform Hornbill Watch reported from outside of protected areas and in parks and gardens of many cities (Datta et al. 2018). The species was previously considered resident in village groves of western Rajshahi Division, Bangladesh (Siddique et al. 2008). However, recent evidence suggests that the species is only a visitor to the country (S. U. Chowdhury in litt. 2020).

Ecology

The species occupies a diverse array of habitats from savannah to dry deciduous forests and urban landscapes (P. Balasubramanian in litt. 2020). It shows a remarkable adaptability to urban environment and was recorded nesting in a hole in a concrete building (Gadikar 2017).

The breeding season in the Eastern Ghats, India, extends from December to April (Santhoshkumar and Balasubramanian 2010). Nests are located in huge trees along streams and rivers; the preferred nesting trees include Melia dubia. Nest hole competition with parakeets and mynas was observed in the riparian habitat (Santhoshkumar and Balasubramanian 2010). During the breeding season, males frequently visit habitations to collect cattle dung, probably for plastering the nest hole (P. Balasubramanian in litt. 2020). The nest is solely sealed by the female using excreta, mud pellets and bark pieces provided by the male (Charde et al. 2011). The female lays 2-5 eggs, and the incubation period is 21 days followed by a 45 day fledging period (Charde et al. 2011, Poonswad et al. 2013). In one study in central India, the date of female entry into the nest was between 9th March and 2nd April. The average length of incarceration of the female inside the nest was 65 days. The total nesting cycle lasted around 93 days with 1 to 3 chicks fledging (Charde et al. 2011).

In the Eastern Ghats, the diet includes fruits (Ficus spp, Diospyros montana and Vitex altissima) and insects (Santhoshkumar and Balasubramanian 2014). The main food items in central India are fruits of  Ficus religiosa and F. benghalensis, followed by F. glomerata and F. lacor (P. Balasubramanian in litt. 2020). Fruits of Pithecelobium dulce, Manilkara hexandra, Syzygium cumini, Zizyphus mauritiana and Thevetia nerifolia are also delivered by the male to the nest inmates (Charde et al. 2011). The species is an important seed disperser of tree flora in the dry deciduous forests of Eastern Ghats; seeds dispersed by the hornbills showed very high germination efficiency (Santhoshkumar and Balasubramanian 2011).

Threats

Dry deciduous forest and riverine habitats, which are important for the species in the Eastern Ghats, are under high anthropogenic stress. In disturbed habitats, 65% of hornbill food species were not found. Riverine habitats are subject to disturbances including agricultural practices by locals, livestock grazing, non-timber forest produce collection (Balasubramanian et al. 2011). Out of its total range, only 6% is optimal habitat (Kinnaird and O’Brien 2008).

Occasional hunting of the species has also been reported from certain parts of its range (A. Datta in litt. 2020).

Conservation actions

Conservation Actions Underway
The species occurs in many protected areas across India. A nursery for plants used by hornbills has been created in the Forest Department field station in Hasnur. Awareness campaigns among Forest Department personnel are carried out. In some areas in India, nest boxes have been installed to augment breeding, which are being used by the species (A. Datta in litt. 2020).

Acknowledgements

Text account compilers
Datta, A., Hermes, C.

Contributors
Balasubramanian, P., Butchart, S., Chowdhury, S.U., Ekstrom, J. & Patil, I.


Recommended citation
BirdLife International (2021) Species factsheet: Ocyceros birostris. Downloaded from http://www.birdlife.org on 24/10/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 24/10/2021.