LINKED PAPER
Hornbill abundance and breeding incidence in relation to habitat modification and fig fruit availability. Pawar, P. Y., Mudappa, D., & Raman, T. S. 2021. IBIS. DOI: 10.1111/ibi.12895. VIEW
Across the tropics, large sections of pristine forest are turned into farmland and plantations. The result is a complex patchwork of protected areas and human-dominated habitats (Bregman et al. 2014). The dwindling size of forest fragments poses a problem to large-bodied bird species that rely on expansive home ranges. In Asia, for example, several species of hornbill have difficulty finding nesting sites and food resources in an increasingly fragmented landscape. A recent study focused on the Great Hornbill (Ocyceros bicornis) and the Malabar Grey Hornbill (Ocyceros griseus) in India. How do these species cope with the development of plantations on the Valparai Plateau?
Gradient
Between January 2017 and April 2018, a team of Indian ornithologists estimated the number of Great Hornbill and Malabar Grey Hornbill across a gradient of tropical rainforest and plantations. For both species, the counts revealed more hornbills living and breeding in the protected area (i.e. the Anamalai Tiger Reserve) compared to the forest sections fragmented by plantations. The researchers attributed this difference to the higher food availability in the rainforest and the lower numbers of large nesting trees in the plantations.
Figure 1. Great Hornbills were observed more often in the protected area (PA) than in the plantations, both when nesting and outside the breeding season. Similar patterns emerged for the Malabar Grey Hornbill.
Conservation
However, despite the lower habitat quality of the plantations, hornbills were still observed year-round in these areas. This observation contradicts the idea that the large-bodied hornbills require continuous stretches of pristine rainforest to survive (Kannan & James 1999). In contrast, the researchers noted that “hornbills can persist in human-modified habitats such as shade-coffee plantations in fragmented landscapes throughout the year because of availability of fruiting trees and traditional nest-sites.” Plantations might thus be able to sustain a breeding population of hornbills and will need to be taken into account when formulating proper conservation strategies (Mudappa et al. 2014). It might not be possible to create continuous stretches of rainforest, but we can at least safeguard the survival of hornbills in fragmented landscapes.
References
Bregman, T.P., Sekercioglu, C.H. & Tobias, J.A. (2014). Global patterns and predictors of bird species responses to forest fragmentation: implications for ecosystem function and conservation. Biological Conservation 169: 372– 383. VIEW
Kannan, R. & James, D.A. (1997). Breeding biology of the Great Pied Hornbill (Buceros bicornis) in the Anamalai hills of Southern India. Journal Bombay Natural History Society 94: 451– 465. VIEW
Mudappa, D., Kumar, M.A. & Raman, T.R.S. (2014). Restoring nature: wildlife conservation in landscapes fragmented by plantation crops in India. In M. Rangarajan, M.D. Madhusudan & G. Shahabuddin (eds) Nature Without Borders: 178– 214. New Delhi: Orient Blackswan. VIEW
Image credits
Top right: Great Hornbill (Ocyceros bicornis) | Angadachappa | CC BY-SA 4.0 Wikimedia Commons
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