I fed a large mixture of cottontail, pheasant, duck, pigeon, jack, squirrel, day old chicks and rarely quail last season to my second year female gos. I guess after years of flying I have a good idea of relative richness of food, cottontail is very light, duck very rich etc., and feed accordingly. Usually I am pretty close to the wt. I expect. I don't have to worry much about aggression as my bird is parent reared, but I still tend to err to the high side and fly her fat more often than having her sharp. I like the idea of a varied diet, and I don't like the idea of buying food and letting carcasses go to waste. I do some shotgun hunting in addition to falconry and also use those carcasses for hawk food [I always shoot non toxic shot]. The vast majority of what my hawks eat comes from the wild.