How birds may use cigarette butts

Stuffing cigarette butts into the lining of nests may seem unwholesome. But a team of ecologists says that far from being unnatural, the use of smoked cigarettes by city birds may be an urban variation of an ancient adaptation.

Birds have long been known to line their nests with vegetation rich in compounds that drive away parasites. Chemicals in tobacco leaves are known to repel arthropods such as parasitic mites, so Monserrat Suárez-Rodríguez, an ecologist at the National Autonomous University of Mexico in Mexico City, and her colleagues wondered whether city birds were using cigarette butts in the same way.

In a study published today in Biology Letters, the researchers examined the nests of two bird species common on the North American continent. They measured the amount of cellulose acetate (a component of cigarette butts) in the nests, and found that the more there was, the fewer parasitic mites the nest contained.

Additional details at Nature.

Photo credit: Manfred Danegger/NHPA/Photoshot