Heard today about this and had to share. Not only are discarded cigarettes a polution problem but are responsible for many wild fires and structure fires.
"Up in smoke: The blaze caused by the nest-building sparrow caused £250,000 in damage"
http://www.dailymail.co.uk/news/article-1172603/The-sparrow-turned-village-shop-ashtray-taking-lit-cigarette-nest.html