A) There is literally a Konoha aviary. It wouldn't be beyond logic to have her with a simple hawk summon for messages/the jutsu.
B) You have Hiden. You have butterfly Hiden. Make a special butterfly if you want specifically made for this jutsu.
C) Creativity. This is a supplementary jutsu. How you do it is meant to be interesting and fit your theme.

I don't care if you use a bird or your Hiden, either way is fine. But keep to your theme.