Metal pollution gradient hissing data

This file contains results from hissing tests performed on female great tits across a metal pollution gradient in Antwerp, Belgium, in 2017. Moving away from the pollution source, the study sites were Umicore (UM), Fort 8 (F8), Fort 7 (F7), Fort 6 (Fort 6/CDE), Fort 5 (F5) and Fort 4 (F4). UM and F8 were grouped into one site for analysis. Hissing behavior is a form of nest defense. Thus, a larger number of hisses indicates more intense nest defense. The ND score (nest defense score) was not used in this paper, but increases with intensity of nest defense. Information on female aggressive and exploration behavior is also contained in this file, where available.