Urban birds are incorporating cigarette butts into their nests for bug-killing action and for insulation, a new study finds.
The discovery, published in the latest Royal Society Biology Letters, helps to explain why so many avian nests include cigarette butts in their construction.
Isabel López-Rull of the Instituto de Ecología, UNAM, and colleagues came to the determination after studying the effect cigarette butts have on parasites. In short, if you're a parasite, you don't want to be anywhere near a cig butt.
"The amount of cellulose acetate from butts in nests of two widely distributed urban birds was negatively associated with the number of nest-dwelling parasites," the authors wrote. "Moreover, when parasites were attracted to heat traps containing smoked or non-smoked cigarette butts, fewer parasites reached the former, presumably due to the presence of nicotine."
The cigarette butts were also found to insulate nests, making conditions cozier for the studied birds: the house finch and the house sparrow. Other birds likely use cigarette butts too, but these happen to be the two species selected for the study.