Hornbill Hunting Impacts Spread of Forests: Study

NEW DELHI: Hunting down hornbills has a direct impact on the spread of forests as the bird is known for its seed dispersal abilities, a study has found.

The study was conducted by the Indian Institute of Science and Mysore-based Nature Conservation Foundation in Namdapha Tiger Reserve and Miao reserve forest in Arunachal Pradesh.

The Namdapha Tiger Reserve is the third largest national park in the country in terms of area. The Miao reserve forest is located to the west of Namdapha National park. Both are known for hornbill sightings. The former is a known to be a well-protected area, while the latter is hugely disturbed.

The study indicated steep decline in both fruiting plants and hornbills, and very low rates of seed dispersal in the disturbed Miao reserve forest, as compared to the Namdapha Tiger Reserve.

The numbers reported showed the extent of damage in heavily disturbed areas. There were 22 times more hornbills, two times greater abundance of hornbill food trees and seven fold higher seed arrival in the undisturbed area of Namdapha as compared to the disturbed Miao reserve forest.

Dispersal of seeds in a forest is very important for retaining plant diversity and maintaining the green cover.

Hornbills are the largest fruit eating birds in the Asian forests, and play a very important role in seed dispersal—they can swallow the whole fruit and regurgitate intact, viable seeds at different locations. Since hornbills can fly far and wide, there is a chance, that the seeds get carried long distances from the parent tree. Their role in maintaining the forest ecosystem is so immense that they are regarded as the "farmers of the forest".

The study said cutting down of forest trees seemed to have had a direct impact on plant abundance, indirectly affecting hornbill numbers and the seeds dispersed by them.

"While the effect of hornbill hunting on forest cover may not be visible over a short time period, the study showed that the number of hornbills was directly linked to the arrival of seeds in the forest. The loss of hornbills is therefore expected to greatly impact the forest cover in the long run," the study said.

"Hornbills are facing extinction in many places and the loss of hornbills would have cascading negative effects on the seed dispersal of plants dependent on them in future", says Rohit Naniwadekar, the lead author of the study.

Hornbills are large, beautiful birds known for their over-sized beaks. Two Indian states – Kerala and Arunachal Pradesh – have the Great hornbill as their state bird. Their unique life cycle – females live inside hollow tree trunks for months bringing up their young, while males fly out to bring food for the family – makes them very special.