Please DO NOT go around throwing birds (including swifts) you find on the ground up into the air!
A bird on the ground that can't get away from you is in distress*. Put it in a quiet, safe place (a closed paper bag or cardboard box w/ a paper towel is ideal) and contact a wildlife rehabilitator for advice.
SOURCE: I've been doing bird and wildlife rescue for nearly a decade.
*The exception here may be fledglings in spring/summer. Call a wildlife rehab if you're not sure.
