I wear a lot of dark or neutral colors. Browns, blues, greys, white, black.... so my birds are used to me wearing those colors.
The one time I walked in to my bird room wearing a bright orange shirt, all my birds freaked out! I immediately turned around, changed shirts and walked right back in! No issues!
Animals, especially prey animals, can be hypersensitive to things like that. If you really want to learn more about animal minds, then check out Temple Grandin's book
Animals in Translation: Using the Mysteries of Autism to Decode Animal Behavior. It helps to give a different perspective of how animals think. There are some areas of the book that aren't necessarily pleasant to read (considering what Temple Grandin does for a living), but it really helps to point out how something so small and minute can have such a *huge* impact on animals!