Why Some Birds Seem to Be Developing a Cigarette Habit | Research from Poland adds to evidence from Latin American countries that compounds in used cigarette butts ward off parasites in bird nests.

Using bellows to smoke the cigarettes mechanically “was the most challenging part of the experiment,” said Michal Gladalski, an evolutionary ecologist who led the study. He is not a smoker and wanted to avoid hurting his lungs or anyone else’s.

Surely there's enough he could collect just from wandering around and looking at the floor?

We have observed this behaviour! We used to have an uncovered ash tray on our terasse that tits came and plundered on a regular basis. We had to get one with a lid to stop them from making a mess every time.