It has been done... essentially flyig wings with a bird shape (only looks like a bird from a distance) and scale models (even some 2X to 10X size...) of birds.

Some interresting methods of controlling the bird models have been tried... including a sort of slotted (feather shaped) wingtip that pivots. (you can't see any difference from a real bird in flight, except he wings don't flap)

There have also been Ornithopters (the wings DO flap and that provides the thrust... no prop) Prop driven and glider versions...

I believe last year there was an article in Model Aviation about some of the scale bird models.