cigarette

House sparrow in Mexico City. Photo Credit: © Víctor Argaez Researchers Suárez-Rodríguez et al., observed house finches (C. mexicanus) and sparrows (P. domesticus) on the National University of Mexico campus in Mexico City routinely pulling apart cigarette butts to obtain the filters. The birds were found to incorporate the filters in their nests leaving researchers to speculate the purpose of used cigarette butts. Using heating elements to attract parasites, they found that probes covered in "used", i.e. artificially smoked, cigarette butts attracted fewer ectoparasites than those that…