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Research review: Hornbills and their role in maintenance of rainforests

First published: Biodiversity of India

The role of birds in maintaining rainforests is frequently under-appreciated. An example in this regard is the Hornbill. Hornbills are large frugivores birds which are more efficient in seed dispersal in terms of wider range of fruit/seed sizes than other small frugivores birds.

Mindanao Wrinkled Hornbill at the Philippine Eagle Center, Philippines

There are total fifty-four species of hornbills found in sub-Saharan Africa, India, and Southeast Asia and New Guinea of which —23 species are fond in Africa and 31 in Asia. Their contribution to the maintenance of forests has been scientifically recognized and they are regarded as “farmers of the forest”.  The most extensive study on feeding behavior of hornbills by Shumpei Kitamura (1) suggests that they feed on 748 plant species from 242 genera and 79 families.  In this report, author also suggests that, survival of the seeds after passing through gut of hornbill is quite good. Also, a significant number of seed species showed enhanced germination efficiency after passing through their digestive system. After feeding, hornbills usually regurgitate or defecate seeds when perched. The home range of these birds, depending on their size, can vary from 700 Hectare to 2400 Hectare with daily movements regularly extend to at least 10 km, which suggests they can be much more efficient than the other smaller frugivores in dispersing seeds at a wider range of territory. Studies by Kinnaird(2) on the distribution pattern of seeds by hornbills suggested that they help in increasing the abundance and diversity seedlings near the nesting site. A relatively long retention time of the seeds in the gut also contributes to relatively wide spread of seeds.

Unfortunately, relatively large frugivores like Hornbills are vulnerable to extinction, as most of the rain forests in Asia are under tremendous anthropogenic pressures such as hunting, and habitat loss or, degradation. Some of these hornbill species are among the rarest in the world, with only ~40 individuals left! Dwindling number of these forest farmers will have reaching effects on the maintenance of the rainforests itself. So, the close association between hornbill population for maintenance of rainforests as well as conservation of rainforests to prevent extinction of Hornbills has to be scientifically examined before implementing any developmental projects in such eco sensitive zones.


1)     Frugivory and seed dispersal by hornbills (Bucerotidae) in tropical forests. (2011) Shumpei Kitamura, Acta Oecologica, 37, (6), 531–541

2)     Evidence for effective seed dispersal by the Sulawesi red-knobbed hornbill, Aceros cassidix (1998), Kinnaird  M.F., Biotropica, 30 (50–55)

Genetically modified plants and agrobiodiversity

There is lot of buzz that is going on whether genetically modified plants (GMOs) should be given clearance or not. There are different points in favor and against this issue. Issues like safety for human and animal consumption, seed security of our farmers, adverse effects on land fertility are some of the most prominent issues which get headlines of all major newspapers and magazines. Another harmful effect of GMOs is loss of agricultural biodiversity. The Food and Agricultural Organization of the United Nations, has already warned the world for the loss of agricultural biodiversity. According to their reports some 75 percent of plant genetic diversity has been lost since 1900 as a result of excessive cultivation of genetically uniform, mass-produced crop varieties. GMO plants are derived from genetic modifications of a specific variety of a plant which produce best phenotypes in terms of either yield or quality. So effectively, all the plants of a field where GMOs are grown are the product of a monoculture. In USA for soybean and maize, two most important crops, GM plants accounts for 93 and 52 percent of total cultivation, respectively. In a country like India, where government has limited control over the distribution of crops on agricultural land, uncontrolled cultivation of GM rice or wheat varieties could lead to a catastrophe. The scenario will even be more serious in case of plants which are the major source of food for the country. For example, a rampant use of GMO rice will result in extinction of many of the native varieties. Imagine a situation where GMO rice is being cultivated on 60% of our rice cultivating areas. Pathogens can always evolve and attack GM plant variety and destroy the produce for that year. This will bring down our economy on its knees.

World map of GMO production (2005). US, Canada, Brazil, China and Argentina produced 95% of world’s GMO crops. (Source: Wikimedia Commons)

I once got an opportunity to ask this question to a top official from Monsanto. In his presentation he had shown the rosy picture how farmers in Gujarat are being benefited by GMO cotton and tried to make a case that India should give clearance to GMO rice. I asked him that if a situation arises that a pathogen has evolved against which your rice variety is very susceptible, then what is the minimum time in which we can provide a new set of seed of a resistant rice variety to our market. He said it can take minimum 6 months to flood the market with such new seed variety. That means it will take minimum 10-12 month that the next rice produce will reach to the market. The question is what will happen in these 10-12 months how will our government feed its citizens.

The protection of agricultural biodiversity is another very important point that our law makers and scientist have to ensure before giving clearance to the GMO plants which provide basic food to our country.

First published on Biodiversity of India 

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