Dogs have a determined carnivorous bias and are perfectly capable of eating meat, even raw meat with beaks and claws and feathers. The latter might provide a problem in the gastrointestinal tract, in which case the dog's response might be to regurgitate the offending feathers.
If vomiting continues, diarrhea lasts for more than a day, or the dog acts sick, it is possible that the bird he ate had a condition such as West Nile virus that is affecting the dog and a trip to the veterinarian may be in order. It is also possible that bones or feathers could stick in the dog's intestines, in which case vomiting would probably occur. In general, vomiting should not be ignored.