We're doing owls too and I haven't been able to find one. I think I might ask the company where I'm getting her invitations from if I can 'buy' a digital copy of the owl and use it for the cake sticker.
But I think if it's a good quality photo and sticker, it will look fine.
Thanks. Yes I might just do the photo with a happy birthday message. The invites I bought are just cheap ones from big w so I'm sure I can't get an image. Either this or I make an owl cake and I'm not sure if I'm up to that