Chickens are kosher, if properly slaughtered. Jews have traditionally eaten chicken. Leviticus 11 and Deuteronomy 14 provide lists of unclean birds without giving explicit rules. By inference, carrion eaters and carnivorous birds are unclean. The birds permitted for Temple sacrifices are, by definition, clean, since no unclean things were allowed as sacrifices. Doves and pigeons (another kind of dove) are permitted as sacrifices. Chickens behave more like doves than the forbidden birds, so that matches the tradition. Rabbis had to grapple with this question fairly seriously when the European community first encountered turkeys imported from the new world. The conclusion was that turkeys are kosher too.