Hoo hoot! Link... Look up here! It appears that the time has finally come for you to start your adventure! You will encounter many hardships ahead... That is your fate. Don't feel discouraged, even during the toughest times! Go straight this way and you will see Hyrule Castle.
I suppose they could have wound up completely ridiculous looking like a dodo or kiwi, since they're supposed to be stealthy. They just really lucked out in the aesthetics! Ninjas with good looks, owls have it all.