Which animals use cigarette ends?

Several species of birds living in urban areas use cigarette butts as pesticides.

Researchers at the National Autonomous University of Mexico analyzed the nests of two species of birds common in North American urban areas: sparrows (Passer domesticus) and Mexican bullfinches (Haemorhous mexicanus).

They noticed how the two species often collected cigarette butts and carried them to their nests.

In fact, nicotine acts as an anti-parasite, allowing them to keep their nests clean and safe.

This behavior was seen as an evolution from their habit of creating nests with aromatic materials, such as mint and lavender, to achieve the same purpose.