I am 15 and was wondering . If it would hurt my lab to retrieve crows.

i don`t think it would it would just be better practice for him

thanx

if your lab is crazy about fetch he should want to go and get what ever you tell him to.
wait he's a lab -- if he is anything like the one's i've trained he goes and gets stuff you don't want him to fetch.
labs love two things fetching stuff and pleasing their owners
he'll be fine on crows