Journal of Threatened Taxa | www.threatenedtaxa.org | 26
November 2019 | 11(14): 14891–14894
Vertebrate prey handling in the Indian
Grey Hornbill Ocyceros birostris
(Aves: Bucerotiformes: Bucerotidae)
James A. Fitzsimons
The Nature Conservancy, PO Box 57, Carlton South,
Victoria 3053, Australia; and School of Life and Environmental Sciences, Deakin
University, 221 Burwood Highway, Burwood, Victoria 3125, Australia.
jfitzsimons@tnc.org
doi: https://doi.org/10.11609/jott.5272.11.14.14891-14894
Editor: Anonymity
requested. Date of publication:
26 November 2019 (online & print)
Manuscript details: #5272 | Received 25 July 2019 |
Finally accepted 27 October 2019
Citation: Fitzsimons, J.A. (2019). Vertebrate prey handling in the Indian Grey Hornbill Ocyceros birostris (Aves:
Bucerotiformes: Bucerotidae). Journal of Threatened Taxa 11(14): 14891–14894. https://doi.org/10.11609/jott.5272.11.14.14891-14894
Copyright: © Fitzsimons 2019. Creative Commons Attribution 4.0 International
License. JoTT
allows unrestricted use, reproduction, and distribution of this article in any
medium by adequate credit to the author(s) and the source of publication.
Funding: The Nature Conservancy.
Competing interests: The author declares no competing
interests.
Acknowledgements: The author was in India courtesy of a Coda Fellowship through The Nature
Conservancy.
Most hornbills (Bucerotidae)
are omnivorous, but the proportions of different types of food in the diet vary
during the year; mostly frugivorous species include more animal protein in
their diet when nesting (Kemp 1995, 2001; Kinnaird & O’Brien 2007; Poonswad et al. 2013).
Besides the larger ground-hornbills of Africa (Bucorvidae),
there are few specific records of how vertebrate prey are handled by Bucerotidae hornbills, particularly in Asia. This is likely to be due to dietary studies
in the breeding season (when most vertebrate prey is taken) focusing on
delivery to the female and young in the nest (e.g., Santhoshkumar
& Balasubramanian 2014). Santhoshkumar & Balasubramanian (2014) consider
information published on the Indian Grey Hornbill Ocyceros
birostris (one of the most common species in the
Indian subcontinent) to be inadequate.
This paper presents an observation of vertebrate prey handling in the
Indian Grey Hornbill Ocyceros birostris and compares this with other accounts for
this species and other hornbill species.
Three Indian Grey Hornbills (including an adult male
and female) were located in a large tree in the Lodhi Gardens, New Delhi,
India, at approximately 10.00h on 30 June 2018.
The hornbills were observed for approximately seven minutes and photos
and video were taken.
The adult male hornbill had a Garden Lizard Calotes versicolor in its bill by the neck
with the head on one side and rest of the body on the other. The lizard was clearly dead at this stage and
photographs show the head of the lizard had been crushed. The male hornbill rubbed the lizard’s head on
the branch 3–4 times at intervals of approximately 20 seconds (Image 1). After a few minutes, the male gave the lizard
to the female perched next to the male (Image 2–4) who moved the prey in the
bill while perched together, with the male calling. Further, the female ‘wiped’ the sides of the
Garden Lizard on the branch (Image 5), before the pair flew off out of
sight. It could not be determined if
further manipulation of the lizard took place before consumption.
Asian hornbills are generally frugivorous but turn
omnivorous in the breeding season (Poonswad et al.
1998), and this is true for the Indian Grey Hornbill (Santhoshkumar
& Balasubramanian 2010, 2014; Kasambe 2011). The
Garden Lizard is a common lizard in India (Das & Das 2018), and the Indian
Grey Hornbill a known predator, but the proportion (and importance) of Garden
Lizards in Indian Grey Hornbill diets during the breeding season varies between
published studies. For example, Kasambe (2011) suggests Garden Lizards are an important
source of protein for female and nestling Indian Grey Hornbills in the breeding
season and both male and female hornbills hunt them. Lowther (1942) recorded Garden Lizard in
their diet but Patel et al. (1997) did not.
Charde et al. (2011a) observed one instance of
a female bringing a Garden Lizard to the nest but Charde
et al. (2011b) observed many instances of this. Santhoshkumar &
Balasubramanian (2014) found Garden Lizards constituted 0.06–0.10% of food
items in the breeding season. These
differences may represent differences in survey techniques, differences in
availability of Garden Lizards or differences in feeding preferences between
individuals or populations of Indian Grey Hornbills. Garden Lizard and other Calotes
species are also consumed as part of the diet of congenerics,
i.e., the Malabar Grey Hornbill Ocyceros
griseus (Mudappa 2000; Paleri
2007; pers. obs. 2018) and Sri Lanka Grey Hornbill O. gingalensis
(Wijerathne & Wickramasinghe
2018).
Most dietary studies for Indian hornbills more
generally document food types being brought to the nest (e.g., Santhoshkumar & Balasubramanian 2010, 2014; Charde 2011a,b) and not the capture, killing or handling of
prey which mostly occurs away from the nest.
An exception is Kasambe (2011) who stated the
Indian Grey Hornbill “severely crushes and kills the Garden Lizard before it is
swallowed”.
My observations, in late June and likely at the end of
the breeding season, suggest the Garden Lizards may be further ‘processed’, after
being killed and before consumption.
This is supported by a 20-second video by Patil
(2014) which shows an Indian Grey Hornbill undertaking very similar behaviour
to my observations, but in that instance the lizard was still alive. The hornbill wiped the sides of the lizard on
a branch but was clearly not trying to kill it with that motion.
Descriptions of other hornbill species using tree
branches to process lizards before consumption clearly focus on killing or
incapacitating the prey. Kannan &
James (1997) noted “Larger prey [including Agamid lizards] were thrashed
against the bough [by Great Hornbill Buceros
bicornis] to incapacitate them”. Li (2016) observed an Oriental Pied Hornbill Anthracoceros albirostris
preying on Calotes versicolor: “flicked
the animal against a branch, perhaps to knock it unconscious” before consuming
it head first. Hong (2014) similarly
described Oriental Pied Hornbill preying on C. versicolor: “The lizard
was swiped against the branch until it was dead”. These descriptions suggest a different, more
forceful technique to purposefully kill large lizards, and are not consistent
with the branch-rubbing behaviour observed in my observations or the video by Patil (2014).
An explanation for the observations described in this
paper may lie in the techniques used by hornbills to process other food
types. For hornbills, most food items
are swallowed whole (Poonswad et al. 2013; Sivakumaran 2019) but Kemp (2001; repeated in Poonswad et al. 2013) stated that “Large items … may be
broken up, separated into edible and inedible parts, as by removing fruit husks
or insect wings, and then crushed or softened in the bill. Certain distasteful foods, such as sticky
fruits or hairy caterpillars, or slimy items, may be wiped on a branch or the
ground before being swallowed”. Kemp
(1995) provided further details: “Others are softened before swallowing, the
hornbill passing them through and crushing them in the bill, which is serrated
in many species, or cleaned of unwanted coverings by being wiped back and forth
over a perch or along the ground, as in the case of hairy caterpillars, slimy
toads, or juicy fruits”.
Garden Lizards do have spines (particularly around the
neck) and elongated scales in places (Zug et al. 2006). Constant wiping of the
head and both sides of the Garden Lizard on a branch could serve to remove
spines, or make them less rigid, before the lizard is consumed whole and head
first. It may also serve to further the
‘softening’ process, through breaking or dislodging bones, prior to
consumption.
This observation and those of Gadikar
(2017) suggest we still have more to learn on the ecology of Ocyceros hornbills in India.
References
Charde, P., R. Kasambe & J.L. Tarar (2011a).
Breeding behaviour of Indian Grey Hornbill in central India. Raffles
Bulletin of Zoology 24(Suppl.): 59–64.
Charde, P., R. Kasambe, A. Pimplapure & J.L. Tarar
(2011b). Nest sanitation in Indian Grey
Hornbill in central India. Raffles Bulletin of Zoology 24(Suppl.):
65–67.
Das, I. & A. Das (2018). A Naturalist’s Guide to the Reptiles of India.
JB Publishing, Shipham, United Kingdom, 176pp.
Gadikar, A. (2017). Adaptations of the Indian Grey Hornbill Ocyceros birostris
in an urban environment. Indian Birds 13: 167–168.
Hong, C.B. (2014). The Oriental Pied Hornbill and the Changeable
Lizard. Bird Ecology Study Group, Singapore. Electronic version accessed 21
January 2019. https://www.besgroup.org/2014/12/13/the-oriental-pied-hornbill-and-the-changeable-lizard/
Kasambe, R. (2011). Indian Grey Hornbill: Study of the Ecology and
Breeding Behaviour Indian Grey Hornbill Ocyceros birostris in central India. Lambert
Academic Publishing, Saarbrücken, Germany, 172pp.
Kannan, R. & D.A. James (1997). Breeding biology of the Great Pied Hornbill (Buceros bicornis) in
the Anaimalai Hills of southern India. Journal
of the Bombay Natural History Society 94: 451–465.
Kemp, A. (1995). The Hornbills: Bucerotiformes.
Oxford University Press, Oxford, UK, 302pp.
Kemp, A.C. (2001). Family Bucerotidae
(Hornbills), pp. 436–523. In: del Hoyo, J., A.
Elliott & J. Sargatal (eds.). Handbook of the
Birds of the World. Volume 6: Mousebirds to Hornbills.
Lynx Editions, Barcelona, 589pp.
Kinnaird, M.F. & T.G. O’Brien
(2007). The Ecology and Conservation of Asian Hornbills:
Farmers of the Forest. University of Chicago Press, Chicago, 352pp.
Li, S.S. (2016). Oriental pied hornbill preying on changeable lizard. Singapore
Biodiversity Records 2016: 88–89.
Lowther, E.H.N. (1942). Notes on some Indian birds. 7. Hornbills Journal
of the Bombay Natural History Society 43: 389–401.
Mudappa, D. (2000). Breeding biology of the Malabar Grey Hornbill Ocyceros griseus in southern Western Ghats,
India. Journal of the Bombay Natural History Society 97: 15–24.
Paleri, A. (2007). Malabar Grey Hornbill Ocyceros
griseus nesting near human habitation. Indian Birds 3: 152–153.
Patel, N., N. Chaturvedi & V.
Hegde (1997). Food of Common Grey Hornbill Tockus birostris (Scopoli). Journal of the Bombay Natural History Society
94: 408–411.
Patil, B. (2014). Grey Hornbill hunting a lizard. Youtube
video. Available: https://www.youtube.com/watch?v=Ygvohf7eJ68. Electronic
version accessed 21 January 2019.
Poonswad, P., A. Tsuji, N. Jirawatkavi
& V. Chimchome (1998). Some aspects of food and feeding ecology of sympatric
hornbill species in Khao Yai National Park, Thailand,
pp. 137–157. In: P. Poonswad (ed.). The Asian
Hornbills: Ecology and Conservation. BIOTEC–NSTDA, Bangkok, 325pp.
Poonswad, P., A. Kemp & M. Strange (2013). Hornbills of the World: A Photographic Guide. Draco Publishing and Distribution, Hornbill Research
Foundation, Singapore and Bangkok, 212pp.
Santhoshkumar, E. & P. Balasubramanian (2010). Breeding behaviour and nest tree use by Indian Grey
Hornbill Ocyceros birostris
in the Eastern Ghats, India. Forktail 26:
82–85.
Santhoshkumar, E. & P. Balasubramanian (2014). Food habits of Indian Grey Hornbill Ocyceros birostris
in Sathyamangalam forest Division, Eastern Ghats,
India. Journal of the Bombay Natural History Society 111: 90–97.
Sivakumaran, M.S. (2019). Predation of swiftlet Aerodramus
sp. by Bushy-crested Hornbill Anorrhinus galeritus in Bornean Malaysia. BirdingAsia
31: 41–42.
Wijerathne, I. & S. Wickramasinghe
(2018). Behavioral
pattern of endemic Sri Lanka Grey Hornbill (Ocyceros
gingalensis) within the breeding and
nonbreeding seasons. International Journal of Biodiversity 2018:
9509785.
Zug, G.R., H.H.K. Brown, J.A.
Schulte II & J.V. Vindum (2006). Systematics of the Garden Lizards, Calotes versicolor Group (Reptilia,
Squamata, Agamidae), in Myanmar: Central dry zone
populations. Proceedings of the California Academy of Science 57(2): 35–68.