Welcome to brain stuff from how stuff works, Hey, brain stuff, Lauren Bogelbaum. Here, the house sparrows and finches of Mexico City may be proud to be called bird brains, and why not. They figured out how to use one of the grossest things on Earth, cigarette butts, to repel two of the other grossest things on Earth, ticks and mites. MoMA birds find their nests under constant and pervasive threat
from these blood sucking, feather feasting ectoparasites. Country birds have easy access to nature's bountiful nest making materials, including certain insect repelling herbs and plants. City dwelling birds, on the other hand, face a concrete and steel urban landscape and must curate their nests from a more anthropogenic or man
made palette enter cigarette butts. A study published in twelve in the journal Biology Letters details the ongoing investigation of an urban population of breeding house finches and house sparrows at the National University of Mexico in Mexico City. The author's found that both species interweaved anywhere from a few to a few dozen smoked cigarette butts into their twiggy eclectic domiciles. In fact, the study concluded, the more butts,
the healthier the nest. Nicotine is an insecticide generated by the tobacco plant to ward off invasive leaf eating arthropods like beetles. Some residual nicotine remains in the fibers of cigarette butts that motherbirds used to line and insulate their nests. It turns out that this nicotine tinged filter fluff has medicinal and pesticidal properties that repel tis, in particular, protecting
MoMA's chicks from a potentially lethal fate. Overall, the study concludes that the more cigarette filter fiber there is in the nest, the fewer ticks and mites, revealing persuasive evidence that parasites don't like cigarette butts and that nests built with these butts attract fewer parasites. But there's no Avian surgeon general, so who decides whether this seemingly beneficial cigarette habit harms the birds or is a savvy and resourceful
example of urban wildlife adaptation. Researchers confirmed that there is some genetic damage linked to the activity, but they believe that the positive life saving anti parasitic effects far outwaigh any long term negative consequences. So you've come a long way Bertie's, and you're helping clean up our cities while you're at it. Interestingly, there's another way that birds may
help combat cigarette but litter. A Dutch startup Crowded Cities is developing the Crowbar and Autonomous training device to teach crows, some of the most competent scavengers in the world, to deliver found cigarette butts to a trash receptacle in exchange for food reward. Today's episode was written by Carrie Tato and produced by Tyler Clang, with kind engineering assistance by
Ramsey yungt. For more on this and lots of other bird brained topics, by which we obviously mean clever and helpful, visit our home planet, how stuff Works dot com.