You're implicitly claiming that crows have second order desires (what you "want to want", as opposed to first order desires, "what you want"). If crows don't have second order desires then this doesn't matter to them, it's just another way of getting food. They're not bothered by whatever it is that's the problem with cigarette butt food, they're incapable of being bothered by that: they want to food so they want to pick up cigarette butts, and they have no capacity to reflect on whether they want to want to pick up cigarette butts, so they're not bothered.

If crows do have second order desires, then it's possible they might be bothered, and then you have an ethics problem. And we actually have more reason to think crows might have second order desires than we do for other animals: crows recognize themselves in mirrors, which requires an awareness of self, therefore they have an awareness of self. An awareness of self is necessary for having second order desires. It's not enough to conclude that they have second order desires, but it's a shred of evidence. However, we usually consider young children to not have second order desires, so I'm fairly skeptical of the idea that crows have them.

It's not clear that there's any ethical violation even if crows do have second order desires, but if they don't, there's no ethical question at all.

Edit: no ethical violation where the crows are the victims in the sense that we're discussing.