An interesting new study released by the journal Biology Letters claims that cigarette butts can actually be beneficial for birds. According to researchers Monserrat Suárez-Rodríguez, Isabel López-Rull, and Constantino Macías Garcia, the cigarette butts help protect bird nests from unwanted guests.
Certain parasites called ectoparasites can have a negative impact on the health and survival of birds. Studies have indicated that the birds’ immune systems have evolved over time to counteract some of the issues caused by parasites. Additionally, some birds have been known to construct their nests with plant materials that naturally repel the pests. Unfortunately, birds that nest in larger cities may have a hard time finding the repellent plants they would customarily use to line their nests.
Urbanization may have forced some of these birds to rely on a more creative form of pest control — cigarette butts.
Smoked cigarette butts contain substantial amounts of nicotine, particularly alkaloid nicotine. Alkaloid nicotine has been used as a pest repellent on crops and to control ectoparasites in poultry. The fact that cigarette butts contain a known pesticide led researchers to hypothesize that they would find fewer parasites in nests where the butts were present.
The study involved house finches and house sparrows breeding in Mexico City at the National University of Mexico in 2011. The results concluded that nests that contained cigarette butts attracted fewer parasites than those without.
Behaviors detrimental to parasites fulfill one condition necessary to scientifically define self-medication. However, in order to qualify for the designation, it would also have to be proven that the birds are consciously introducing the materials into the nest to reduce the number of parasites. It would also have to be proven that the reduction of parasites was significant enough to positively effect the health of the birds.
If nothing else, the cigarette butts are certainly beneficial in reducing the number of parasites in the birds’ nests. Whether or not the birds have consciously realized this may be very difficult to prove.