Here is a craft one of our Pre-K classes made recently. I'm not really sure if they are baby birds, but hanging on the wall that is what they reminded me of.
You will need:
One small paper plate
One large paper plate
The first step is to attach the small paper plate to the large paper plate. The teacher had done this with a stapler. Feel free to let you little one undertake this task if you think they are able.
Then you add the finishing touches. The teacher had used construction paper for their birds' decorations: yellow beak, (which is open, I think that is why it looks like a baby bird), yellow feet, blue feathers, and an eye.
I was thinking you could go all out here. You could use feathers, felt, paint (I was thinking a robin--painting half of the large plate orange/red and the rest brown),
Maybe you could rip some paper and add it all over for lots of feathers. Maybe you have material the children could cut and glue all over.
This is definitely a craft where the sky or yowhat you have around is the limit. Have fun!