On: Torresian crows have learned how to make a meal of...

[IntronExon]

They’re stealthy hunters, so bright aposomatic coloration would be counterproductive. I also believe that there is some aposomstic scent markers and behavior in the case of cane toads, it’s just that native Australian fauna has taken time to adapt.

http://www.pnas.org/content/101/49/17150

They’re not “learning” to avoid, but selection pressures are having the same end result.