Baby blackbird

I have a baby blackbird hopping around my garden and unable to fly. I have been watching and you can get really close but haven't seen a parent come to feed it at all. It is currently sat on my birdbath with no sign of an adult though it keeps chirping and flapping at passing birds.  I am worried that it may be injured or something and that the cats will get it. I know that they eat worms and have put out mealworms just in case but am not sure he is eating them. What should I do as he has been there for two days now.