Starlings protect their chicks from parasitic insects by lining their nests with certain herbs.

References

"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)

Book
The Hidden Powers of Animals: Uncovering the Secrets of NatureMarshall Editions Ltd.January 1, 1970
Dr. Karl P. N. Shuker

Organism
StarlingsSturnidaeFamily