GUWAHATI, Feb 10 – Common birds inhabiting the State’s agricultural landscape can be used as effective bio-pest controllers – including against pests that have developed immunity to chemical pesticides. Unfortunately, agriculturists are largely unaware of the important role played by the birds in controlling insects and rodents.
According to the report of the All India Network Project on Agricultural Ornithology covering North Bank landscape, i.e. Sonitpur, Darrang, Lakhimpur and Dhemaji districts (plain zone) conducted by Assam Agricultural University (AAU), as many as 96 species of birds occurred in the area’s agricultural landscape of which a majority were found to be effective against pests. Again, 58.3 per cent of the birds occurring in agricultural landscape were found in paddy fields, with 49 of those being common/resident species.
Dr Prabal Saikia, Principal Scientist, Agricultural Ornithology and Entomology, AAU, who did the study says that with some simple techniques, the scope for utilising beneficial birds for suppression of insects, worms and rodents can be increased manifold.
“Our experience has shown that low-cost nest boxes and perches can attract wide ranging insect-eaters and in good numbers. This in turn impacts pest control in a favourable manner,” he says.
According to the study, low-cost nest boxes designed for beneficial omnivorous birds were mainly occupied by house sparrow, Eurasian tree sparrow, great tit, magpie robin, myna and spotted owlet.
“Eurasian tree sparrow and house sparrow readily occupied earthen nest boxes and nest boxes made of shoe box (70 per cent occupied). Thirty per cent nest boxes made of wood were occupied by spotted owlet, 40 per cent by magpie robin in mud pot, and by common myna in waste biscuit tin,” Dr Saikia says.
Erecting T-shaped perches in paddy fields is another easy way to attract insect and rodent eaters. The study found a total of 11 bird species utilising the T-perches in the fields. The highest number of nine species were recorded in September — coinciding with higher pest prevalence — and the lowest (only 2) in February.
“The frequent visitors were black drongo and pied myna. Black drongos used the perches as perching site and devoured the larvae by taking short flights and picked them from the paddy field,” Dr Saikia says.
Bird observations in paddy fields during September revealed black drongo (30.32 pc), pied myna (21.52 pc), common myna (10.76 pc), jungle myna (10.76 pc), paddy field pipit (10.34 pc) green bee-eater (9.54 pc), shrike (4.56 pc) and red-vented bulbul (2.26 pc) to be the dominant species using T-perches.
The dominant species in mustard field during December were black drongo (66.66 pc)) shrike (7.93 pc), stone chat (6.34 pc), common myna (4.76 pc), bee-eater (4.76 pc), red-vented bulbul (4.76 pc), pied myna (3.17 pc) and plaintive cuckoo (1.58 pc).
“Significantly, use of perches and tree branches in tomato experimental field recorded less fruit borer infestation (8.04 pc) caused by Heliothis than the control plot with netting (17.90 pc),” Dr Saikia says.
A large-scale demonstration of T-perch in paddy fields in ten districts covering 1,000 hectares was made during 2011-12 kharif season.
A low-cost sparrow nest box adoption programme was also launched in the State with the mandate to provide safe predator-proof nesting space to a species in distress, to involve common people by motivating them to install nest boxes in their homes, and to adopt villages on the periphery and install nest boxes in the houses without any cost.
Two thousands sparrow nest boxes were distributed among the students and farmers with hundred wooden nest boxes for barn owl.
Dr Saikia says damage caused by some depredatory birds such as baya weaver, munia and rose-ringed parakeet can also be minimised by adopting simple techniques.
“Available bird management techniques like reflective ribbon to protect rice crop from baya weaver and munia in maturity stage was employed in the university farm, farmers fields, and in the Field Trial Station at Lakhimpur,” Dr Saikia says.
Organic fields recorded greater number of birds than fields where pesticides and inorganic fertilisers were used.