Hullin 22: Doves and Young Pigeons

A new mishnah! On bird offerings - and at what age they are suitable for offerings, depending on whether they are "doves" or "pigeons." What about the transition age? Note that both ages need to be stipulated because logic might steer us astray otherwise. Also, the Torah is specific to prevent us to think that all doves and/or all young pigeons would be acceptable. With key yellowing of plumage making the difference.