It's also twice her size and possessing any number of limbs more than the yukkuri mother here. All of which are far more effective than two braids.
I mean I guess she could throw herself at it. In all honesty that's probably the most effective thing she could use to defend herself, but the crow would probably just carry its food away with it a short distance away, finish eating, and leave.
Or, it'd eat what piece it had, go a short distance away, and just hop in from another angle. It doesn't exactly feel threatened.
Cataphract said: To be fair, what could she do? Judging for color, it's a crow. And crows are some of the smartest birds out there.
That sir, is a raven. Much larger than a crow and much more common in japan. Assuming the adult Reimu is about the size of a basketball, then it'd have to be Raven.