I also have a Sulmateler chick and was researching this. I read somewhere that when the chicks are about 2 weeks old and have more feathers, if you see a black stripe on their wing feathers, then it is male. They are not auto-sexed, so I am not sure if this is 100% the case for every Sulmtaler. In all the photos I have seen of Sulmtaler hens, they are all wheaten and white speckled. None of the hens appear to have black feathers. My 1 week old Sulmtaler chick is developing its wing feathers right now and it appears that there is black mixed with white on its wings. I believe it will turn out to be a male, but will update once I know for certain. I hope this helps.