Considerable attention has been paid to the effects of endocrine disrupting chemicals in aquatic environments, but rather less attention has been given to routes of contamination on land. A new study by researchers at Cardiff University, reveals that wild birds foraging on invertebrates contaminated with environmental pollutants, show marked changes in both brain and behaviour: male birds exposed to this pollution develop more complex songs, which are actually preferred by the females, even though these same males usually show reduced immune function compared to controls.