Ok...maybe you can do an experiment.... Measure his food.. like how much you normally give him...(do it on a day you have off) watch him whiles hes eating and when hes done see how much theres left.... then reduce the food amount you give him if theres still some left the next day... then reduce it more? if hes really hungry... he would eat all of it. Maybe hes just being a good animal friend and saving the crows some food?