Birds in Mexico City are snuffing out parasites with cigarettes.
Not by puffing away, mind you, but by lining their nests with used cigarette butts, a new sudy published in Biology Letters suggests.
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According to researchers at St. Andrews University, the nicotine and other chemicals in discarded filters act as a natural pesticide that repels parasitic mites, BBC News reported.
Scientists studied the nests of house sparrows and house finches in Mexico City and found that, on average, the more cigarette butts a nest contained, the fewer parasites.
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To test the effect, they placed traps in each nest containing cellulose fibers from smoked and non-smoked cigarettes, Nature.com reported.
Fewer parasites were attracted to nests lined with the nicotine-laden smoked butts, according to the study.
Scientific American called the study a "wonderful" example of wildlife adapting to urban environments.
However, the verdict is still out on how this trend may affect the health of Mexico City's birds.