Google Image Search has a new option that lets you restrict the results based on their color. For now, the option is not available in the user interface, but you can tweak the search results URL to try it.
Searching for [red bird] shows good results, but you can still find some unrelated images. What if you search for [bird] and restrict the results to red images? Here's the URL:
(you can replace "red" with "blue", "green", "teal", "purple", "yellow", "orange", "pink", "white", "gray", "black" and "brown")
You can try the new feature using this simple drop-down:
7 minutes ago