I presently own what I believe are two "male" African geese. I have owned them now for almost three years. There has never been an egg laid, causing me to believe they are males. They are the only two geese on my hobby farm and they are strictly pets. One is much smaller than the other and the knob on it's head is shaped differently than the larger of the two. They are of course inseparable. The smaller of the two seems a bit off. He is not vocalizing and simply not himself. If I loose him, is it possible to bring in another for the survivor and if so does it absolutely have to be the same breed?