Picture an urban environment. Now think about animals that capitalize off of resources discarded by humans. Most of us will conjure up an image of a rat foraging in a dumpster or a pigeon making off with some lunch scraps. But what about songbirds?
A recent study from researchers at Mexico’s Autonomous University of Tlaxcala found that urban songbirds benefit from lining their nests with an unlikely material: cigarette butts.
Nest-building birds have long relied on the essential oils in aromatic plants to repel parasites that can build up in their nests and threaten their young. Because nicotine is an insecticide, it can have a similar effect. Butts from smoked cigarettes retain high levels of nicotine and other compounds that act as bug repellents.
The new study, published in Biology Letters, provides the first evidence that smoked cigarette butts may help urban birds repel nest parasites. The researchers investigated how parasites responded to cigarette butts by using heat traps lined with fluff from smoked and unsmoked cigarettes. Parasites strongly avoided fluff from smoked cigarettes.
Then the team scoured Mexico City for vacated house sparrow and house finch nests. Lab analyses found that nests containing the highest percentage of smoked cigarette butts had the lowest number of parasitic mites.
But before we do away with urban ashtrays, let’s note that cigarette butts contain a large number of toxic substances. The impact these chemicals have on nestlings is unknown, and could outweigh the benefits of a smaller parasite burden.
Web Links
Scientific American
Incorporation of cigarette butts into nests reduces nest ectoparasite load in urban birds: new ingredients for an old recipe?
http://rsbl.royalsocietypublishing.org/content/9/1/20120931.full
Photo, taken on March 7, 2007, courtesy of Bill Blevins via Flickr.
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