Sneha Vijayakumar and Priya Davidar observed an interesting pre-roosting behaviour of a pair of Malabar Pied Hornbills (Anthracoceros coronatus) during December 2006 to February 2007 in northern Karnataka, India.
During the pre-roosting period of 1600-1830 hours, the hornbills were vocalising loudly, preening, feeding and hopping from branch to branch. In addition, pairs of the same sex were seen locking bills, as in the two males in the above image by Sudhir Shivaram. However, pairs of different sexes touched bills gently. Such behaviour has also been reported by Reddy (1988).
When flying to the pre-roosting trees, there were pairs performing mid-air acrobatics, locking bills and free-falling to suddenly break free before flying to the roosting trees. The image below by Sachin Rai shows two males locking bills while in the air. This behaviour is believed to be simply a form of play chasing.
In Southern Ground Hornbill (Bucorvus leadbeateri), Kemp (2001) reported juveniles engaging in fast aerial chases with bill wrestling. Cranbrook & Kemp (1995) reported aerial “casque-butting” in Great Pied Hornbill (Buceros bicornis) and Helmeted Hornbill (Rhinoplax vigil). This behaviour was seen only between males of the species, possibly a sort of dominance display.
1. Cranbrook, E. & A. Kemp, 1995. Aerial casque-butting by hornbills (Bucerotidae): a correction and an expansion. Ibis 137: 588-589.
2. Kemp, A. C., 2001. Family Bucerotidae (Hornbills). In: del Hoyo, J., A. Elliott & J. Sargatal (eds.). Handbook of the birds of the world. Vol. 6. Mousebirds to Hornbills. Lynx Editions, Barcelona. Pp. 436-523.
3. Reddy, M. S., 1988. Some aspects of ecology and behaviour of hornbills, with special reference to Anthracoceros coronatus (Boddaert) from North Kanara district of Western Ghats. PhD. Thesis, Karnataka University.
4. Vijayakumar, S. & P. Davidar, 2007. Observations on possible social play in the Malabar Pied Hornbill Anthracoceros coronatus at Dandeli, northern Karnataka. Indian Birds 3(6): 228-230.