Sparrows use cigarette butts to deter pests, scientists find

Cigarette butts are widely reviled as an urban nuisance but birds in Mexico City see them as a boon, apparently using them to deter parasites from their nests, scientists say.

Local sparrows and finches incorporate smoked cigarette butts in their nests to provide cosy cellulose lining for their chicks and nicotine to ward off mites, they believe.

A team led by Constantino Macias Garcia at the National Autonomous University monitored 57 nests and found that the tally of bugs declined as the number of smoked butts in each nest increased.