I have read that the chimney swifts feet and tail are adapted for hanging onto the vertical surface of the chimney wall. This makes it very difficult for them to take off from any position other than vertical, so if you ever see one on the ground and think it ill because you can walk right up to it, just pick it up and throw it into the air and it will take off - it just can't do it from the ground by itself. I, too, have other questions about them. Do they roost in chimneys all year long or just at certain times, do they use the same chimney every night, are they migrating now? Thanks for any answers. Francine Nietubicz