By calling, I mean incessantly, not the occasional cry overhead.

Not a peregrine falcon because it lacks the bandit mask.

More likely a juvenile sharp-shinned hawk ... screaming for its parents to come feed it.

http://www.peregrine-foundation.ca/raptors/Hawks/sharpie52.html

Thanks!

Would the parents still be feeding it, then, in this transitional stage?

It thinks they should :)

They might be feeding it away from the nest occasionally, but after a while the offspring has to hunt successfully or die.

Ah. I've seen sparrows and crows feeding flighted young. I don't know why it never occured to me that hawks might (for a while, at any rate. I doubt the song birds keep it up forever, either).

Thanks! And thanks for the link, too.