I can't wait to have some kids mainly because before they learn to talk and thus protest, I can dress them up as whatever I want for Halloween!
Martha Stewart. Owls are EVERYWHERE in kids stuff. There are lots of good ideas on her site if you are the crafty type.
Here is a very simple tutorial for a No-Sew Infant Parrot costume. Best of all the feathers and wings are in the back so your baby will probably not even notice that they are wearing an adorable costume!
Not everyone has time to dust off the old sewing machine or glue gun though. Recently I came across a very cute site called Chasing Fireflies. Their costumes are on the pricey side, but your kid will be one in a million in their adorable tree frog costume.
Another unique option is finding kids costumes on Etsy.com. Let someone else do the heavy crafting and then reap all the compliments! Just make sure you order early to allow plenty of time for the seller to ship and always read entire listing carefully, especially if it is your first time using Etsy. The variety of handmade and unique items on Etsy is endless. A close friend of mine makes the MOST adorable crocheted mermaid tails for infants. Her shop is called Willows Garden and is filled with the cutest crocheted baby photo props and hats.
Full disclosure: I do not have kids yet and these are just suggestions that I think would work. When I have kids I will be dressing them as something so freakin cute for Halloween.