Birds are one of the most valuable bioindicators and biomonitors in an ecosystem. The population levels of birds, their breeding practices and habit changes are being studied in a number of countries across the world. While a number of these studies are aimed at the conservation of birds, a substantial number are aimed at understanding the effects of pollution. And perhaps providing an early warning system on the possible fallouts. A clear example of this is the story of the ban on ddt in the us. Birds of prey were declining, and there was increased incidence of eggshell breakages as a result of the thinning of shells. This led to observation of the effects of ddt on wildlife, and its eventual identification as an environmental contaminant.
Essentially, birds are important cogs in the working of the ecosystem. Some species of birds, for example, are the pollinating agents for flowering plants and fruit bearing trees. Also, insectivorous birds are natural pest and insect controllers. They play an important role in maintaining the balance of the ecosystem by consuming pests that prey on plants. It is in this role that they are particularly useful agents for farmers. In a space where the right balance between birds and their environment is maintained, farmers would spend much less on pesticides and insecticides. This also reduces the rate of soil degradation.
This aspect, in particular, has fascinated me. I have been studying the relation between birds, pests, insects and pesticides in Malda district, West Bengal, for years. It is evident that the use of pesticides and insecticides reduces the role of our insectivorous avian friends. What is less studied in India is the role pesticides play in directly or indirectly killing pollinator and insectivorous bird species. My studies in Malda have led me to conclude that there is a direct link between increased use of pesticides and increased incidence of bird deaths.
Mango trade is one of the most important businesses in Malda. The district is famous for the quality and taste of its many varieties of mangoes