I think many times the mamas just simply stomp on them as they are hatching or shortly thereafter. It appears that is what happened to the 2 goslings that managed to hatch under PK a couple weeks ago. They were healthy looking, but just flattened.
Jan in the jungles of NE Texas. Home to geese (emdens and Canadas), ducks (calls, mallards, runners, Penkins, rouens, muscovies, ringed teal, Mandarins), emus, pheasants (silvers, red goldens, ringnecks, Amhersts, peafowl, doves (ringneck, white, diamond), button quail, 2 Great Pryenese guard dogs, parakeets, a cocatiel, turkeys (Rio Grande, royal palm, blue slate) and about a dozen or so breeds of chickens, both bantam and lg. fowl.
