The nests of house sparrows are kept free of parasitic insects by a lining of leaves from the neem tree, containing insect‑repelling compounds.

“During an outbreak of malaria in Calcutta during 1998, Dr. Dushim Sengupta and fellow scientists at Calcutta’s Center for Nature Conservation and Human Survival were surprised to witness house sparrows lining their nests with (and also eating) leaves from the paradise flower tree (Caesalpina pulcherrima), a species whose leaves are rich in the anti-malarial drug quinine. Confirming that their choice of leaves was deliberate, the sparrows swiftly gathered fresh leaves of this same species when the scientists removed those already lining their nests. Moreover, before the malaria outbreak, these birds has been using leaves from the neem tree (Azadirachta indica) for nest lining. These contain high concentrations of insect-repellent compounds, which are of great benefit to birds rearing nestlings, who are vulnerable to diseases spread by insects and to nest-dwelling parasitic insects.” (Shuker 2001:216-218)


“Similarly, in 2000 Dr. Helga Gwinner and a team of researchers from the Ornithological Unit of Germany’s Max Planck Society revealed that starlings (Sturnus vulgaris) lined their nests with herbs that ward off or kill nest parasites, such as fleas, lice, and mites. Experiments in which some nestlings were reared in nests lacking these herbs (and in which parasites therefore thrived) showed that these nestlings were anemic; nestlings reared in herb-lined nests were heavier and had stronger immune systems, as confirmed by the presence of greater quantities of infection-fighting cells in their blood.” (Shuker 2001:218)

Last Updated May 1, 2020