Bluebird rescue

Hi group. I'm betting there are some of you out there who are more
naturalists than me. I found a little Blue Jay chick under our bush. It
definitely seems in distress - I gave a saucer of water and went and bought
some earthworms. Wouldn't offer at either one. Just sits there looking
around. Been there for some time because you can see its crapped a couple
of times but hasn't hardly moved. I'm sure it must be from a nest in a tree
near us but the parents have obviously abandoned it at this point.
I know this could mean that there is just something wrong with it and
honestly I pretty much willing to let nature take its course, EXCEPT we have
a lot of cats in the neighborhood and I don't like that scenerio. It's not
a little tiny thing. Looks almost like a normal bird in the body, feathers
and markings. Just the chick like short stuff on its head and tail feathers
just beginning to sprout, but no length.
Any suggestions. (Hit it will a shovel is not the type of 'solution' I'm
looking for.)
Thanxx
Bill Brister