Poultry Talk Ontario (pto.ca)

G'day folks...amidst all the hubbub and craziness of preparing in this holiday season, I have had this niggling wee question on my mind..crossbill..has it been determined as to the cause?..abnormal development in the egg during incubation or a genetic thing?...i have encountered this a few times and altho i don't breed much, I would like to in the near future and if this is definitely a genetic thing then I would cull with wild abandon..however, if it is something that just happens in incubation and the unfortunate chick is able to manage eating and drinking okay then I really don't care...anyone know?

I think it is indeed genetic, I would cull the one born with it but not the parents, I think it is recessive so just don't breed those parents together again.

I had a severe cross beak hatch from an incubator batch. The chick (thankfully) didn't live long. I fully blame humidity and or temp fluctuations. In the same hatch I had one that pippped and stopped. When I cracked the egg open the chicks brain was sticking outside of its skull .
My sister in law incubated a bunch of my oegb eggs once and hatched 2 cross beaks out of 6. The parents of those chicks had hatched MANY healthy/perfectly normal chicks without any sign of crossbeak. Again-I blame poor incubation.
It seems to me that there IS a genetic component to cross beak. But I think we humans can sometimes duplicate it by messing with mother nature and not doing it as well as a hen can. This is why my incubator has remained packed away collecting dust.

I agree wholeheartedly. I admit to horrid incubation results and place the blame squarely on me.
Charlie had cross-beak. He got sick as a young chick but survived. I believe that this might have happened during early development.

I don't honestly know which it is, Tom, but I suspect from my own very limited experience that it's both...a genetic predisposition perhaps, coupled with a snafu during incubation. I have hatched very few crossed beaks, and I have not allowed any of those to survive (if they're severe and involve incomplete closure of the skull like Happy's chick, they don't live long anyway) because a crossed beak present at hatch WILL get worse as the bird grows and said birds require special care and I have enough "special" birds already lol...but looking back, any that I have had all hatched in humid summer months. Charlie' the Brabanter's beak was the worst I'd ever seen in an animal that lived, but oddly enough he did NOT have it when he hatched, at least not that I could tell. Charlie ate, drank, and mated like a normal rooster. I have a handful of mutt offspring from him, and none had any deformities at hatch. I have heard it said that crested breeds are more likely to end up with skull deformities, and again with my own limited experience I have found that to be true but cannot say for certain.