Some vets will, some won't. An avian/exotic vet is the best bet, but not everyone has access to one and some don't consider a chicken to be 'exotic'. Some of them will try, many don't know a lot about birds. It's worth calling and asking questions, then you can decide if you want to do that. A fecal test is the same for all species, so that shouldn't matter, if you can find a vet that will do it for you. If you have other animals that are patients of a regular vet, they may be willing to do a fecal for you even if they don't see birds.