Nests lined with cigarette filters

Urban birds have to survive in hostile tree-less cities. Basic resources for nesting, food and shelter are being eradicated. The House Sparrow (Passer domesticus) now adds one of the most abundant substance in a city, namely cigarette butts into their nests. In the absence of plants for self-medication, city birds can pick from a wide array of 4.5 trillion cigarette filters to line the nest for their young with toxic garbage that might repell bugs from their dwelling.

Biology Letters: "Incorporation of cigarette butts into nests reduces nest ectoparasite load in urban birds: new ingredients for an old recipe?"

Images
- Franz Marc - The Dead Sparrow 1905
- Permeable cobblestones with cigarette litter, Berlin