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Birds eat million tonnes of insects, keeping them under control

Washington: Birds around the world eat 400 to 500 million metric tonnes of beetles, flies, ants, moths, aphids, grasshoppers, crickets and other arthropod per year, claims a study. The research highlights the important role birds play in keeping plant-eating insect populations under control, according to the study published in the journal — ‘The Science of Nature’.

Nyffeler and his colleagues based their figures on 103 studies that highlighted the volume of prey that insect-eating birds consume in seven of the world’s major ecological communities known as biomes. This amounts to between 400 and 500 million tonnes of insects per year but is most likely to be on the lower end of the range. Their calculations are supported by a large number of experimental studies conducted by many different research teams in a variety of habitats in different parts of the world. “The global population of insectivorous birds annually consumes as much energy as a megacity the size of New York. They get this energy by capturing billions of potentially harmful herbivorous insects and other arthropods,” said Nyffeler.

Further, the researchers estimated that insectivorous birds together only have biomasses of about three million tonnes. Nyffeler said the comparatively low value for the global biomass of wild birds can be partially explained through their very low production efficiency. This means that respiration takes a lot of energy and only leaves about one to two per cent to be converted into biomass.

“The estimates presented in this paper emphasise the ecological and economic importance of insectivorous birds in suppressing potentially harmful insect pests on a global scale, especially in forested areas,” explained Nyffeler, who said that this is especially so for tropical, temperate and boreal forest ecosystems.