Hummingbird please help!?

I found a hummingbird in a wild cats mouth and quickly grabbed it. I looked around on it and it seems healthy but cant fly it seems to be a fledgling judging by its mouth and tail. It cant fly and unfortunately it wont stay in the tree and the cats are trying very hard to get it. Im currently nursing it back to health since it was hungry, which bring me to... What can i feed it besides small insects and the sugar water? Is there something easier so i dont have to continue finding ants? Perhaps egg yolk as I read? Im just not sure and would like to know!