The setting is present-day America, probably the Pacific Northwest for a short time and then Washington, D.C.
I'm writing an original novel involving gryphons, who, through the relevant plot thread, end up on Earth. Specifically, two of them, one of whom is about 4'9" at the shoulder and the other of whom is about 5'6". They are about the same proportions as a lion, plus giant hawk wings joined at the trapezius/shoulder joint. Their planet is smaller than Earth, and they're not used to the gravity - not to the extent that they fall over at the drop of a hat, but it's disorienting. They're close enough to cats to be classed as mammals, and they breathe oxygen, digest food the same way, have similar (to a raptor's) ocular structures, etc. Since this is set in the middle of suburbia, the first person to see them calls 911 shrieking frantically about a bear or a giant lion or something, and animal control shows up.
Since omg lions with wings, wtf, the protagonists aren't killed on sight, but tranquilized and the feds get involved and... and... and something or other.
I'm trying to figure out a) what kind of tranquilizer animal control would use on a five-foot-tall gryphon, b) at what point it would wear off for the bigger and smaller gryphons, and c) something plausible that the U.S. gov't would do with them (keep them doped up, put them in a cage, isolate them, whatever) before discovering that both of them are
Thanks in advance to anyone who can help!