Sparrows and Jitterbug the foster pet

It's been a little windy here and I think that caused a bunch of birds to leave their nests a little prematurely. A couple days ago I spent a lot of time watching two baby sparrows hop around the yard. I put out some little water dishes for them. They could only fly about a foot high and would just be really still and silent when I got close. The next morning there was only one sparrow, I'd like to think that one learned to fly in the night, but more than likely a cat found it... and sadly, the other one drowned the next day in the chicken's water (I emptied it so it was only an inch deep precisely to prevent this!!!). :( Here are some pictures I took of the sparrows when they were hopping around:
Sparrow #1 hiding in a rose bush
Sparrow #2 hiding in a cinder block

Then yesterday when I was picking mulberries there was a bird on the ground also getting mulberries. It tried to get away but it has a broken/dislocated leg and did this spastic sideways hopping and flapping dance trying to get away. I put it in a big open cardboard box with some bedding and a water dish and have been feeding it more mulberries and will try to find it some bugs and seeds tomorrow. I don't know why it can't fly, but it can't. Hopefully it will be able to fly away but I think something else is wrong with it too. It has reaaaally long toenails and it's beak seems too long as well. When I was young we had a parakeet that we found in the alley with similar issues. I thought it was a cowbird, but then when I look at cowbirds online they all have dark beaks (this one has a yellow beak, partially stained dark from mulberry juice).... anyone know if this is a cowbird? It's very iridescent. If not, what is it?
Jitterbug the foster pet