I was listening to an episode of the Nature Guys podcast (thanks to whomever suggested that in the podcast thread) about the Belted Kingfisher, and I heard it mentioned that high mercury levels in the water can affect the fisher’s feather colouration, making them darker.
This lit up a bulb for me because both shots I have of this bird have much darker colouration than any of the guide samples I’ve seen. I honestly thought something must have gone wrong with my camera or its settings when I opened the first shot at home.
Now I’m curious. What other species do you know about where pollutants affect their colourations?