EPOW - Ecology Picture of the Week

Kingfisher with Stork Bill

Stork-billed Kingfisher (Peargopsis [prev. Halcyon] capensis capensis), Family Alcedinidae
Royal Chitwan National Park, Nepal

Explanation:  Kingfishers generally have large bills relative to the width of their heads.  But why does this species, shown here in the mixed sal forests of southern Nepal alongside streams and rivers, have such an oversized bill?

I found no specific studies of this species' bills-size adaptations per se, but I will venture here a hypothesis.

Studies of other species of kingfishers in sympatry (that is, whose distribution ranges overlap) suggest that differences in their bill sizes may have arisen to reduce competition for food.  Whether this explains the large "stork bill" of this species is to be determined, but there are a number of other species of kingfishers within the range of the large Stork-billed Kingfisher.  

Information:
     Borah, J., M. Ghosh, A. Harihar, B. Pandav, and G.V. Gopi.  2012.  Food-niche partitioning among sympatric kingfishers in Bhitarkanika mangroves, Odisha.  Journal of the Bombay Natural History Society 109(1&2):72-77.
     Kasahara, S., K. Katoh.  2008.  Food-niche differentiation in sympatric species of kingfishers, the Common Kingfisher Alcedo atthis and the Greater Pied Kingfisher Ceryle lugubris.  Ornithological Science 7(2):123-134.
     O'Connell, D.P., D.J. Kelly, N. Lawless, A. Karya, K. Analuddin, N.M. Marples.  2018.  Diversification of a ‘great speciator’ in the Wallacea region: differing responses of closely related resident and migratory kingfisher species (Aves: Alcedinidae: Todiramphus).  Ibis 161(4):806-823.