Data from: There is no such thing as a free cigarette: lining nests with discarded butts brings short-term benefits, but causes toxic damage

Adaptation to human-modified environments such as cities is poised to be a major component of natural history in the foreseeable future. Birds have been shown to adapt their vocalizations, use of nesting places, and activity rhythms to the urban environments, and we have previously reported that some species including the house finch (Carpodacus mexicanus), use cellulose from smoked cigarette butts as lining material and thus reduce the number of ectoparasites in their nests, probably because the nicotine repels arthropods. Nicotine is only one of hundreds of potentially harmful substances found in cigarette butts. Here we investigated whether the presence of such chemicals is harmful for house finches adding cigarette butts to their nests. We found that hatching and fledging success and chick immune response were all positively correlated to the proportion of the nest that was made up of butts. However, the signs of genotoxicity in the blood cells also increased with the proportion of butt cellulose in the nests. Although we have not measured the effect of genotoxicity on post-fledging survival and breeding success, it seems that bringing cigarette butts to the nest has negative consequences that may counterbalance the benefits of using them as ectoparasites repellents.

适应城市等人类改造环境，将成为可预见未来自然历史的重要组成部分。已有研究证实，鸟类能够调整其鸣唱行为、巢址选择与活动节律以适应城市环境。本团队此前曾报道，包括家朱雀（Carpodacus mexicanus）在内的部分鸟类物种，会利用吸过的香烟滤嘴中的纤维素作为巢内衬料，以此降低巢内体外寄生虫（ectoparasites）的数量，其潜在机制可能为尼古丁可驱节肢动物。然而，尼古丁仅是香烟滤嘴中数百种潜在有害物质之一。本研究旨在探究这类化学物质对在家朱雀巢中添加香烟滤嘴的个体是否存在危害。我们发现，雏鸟的孵化成功率、离巢成功率与免疫应答均与巢内滤嘴纤维素的占比呈正相关。但与此同时，血液细胞中的遗传毒性（genotoxicity）迹象也随巢内滤嘴纤维素占比的升高而增强。尽管我们尚未测量遗传毒性对雏鸟离巢后存活率及繁殖成功率的影响，但整体来看，在巢中使用香烟滤嘴存在负面效应，这种效应可能抵消其作为体外寄生虫驱避剂所带来的益处。