[MrOrelliOReilly]

Did you actually see the bird? Some animals make sounds that are deceptively similar to birds (ex chipmunk chirps). Merlin won’t recognize these as “not a bird”; it just doesn’t recognize the sound at all.

Usual disclaimer IANABL (I am not a bird lawyer)

[0points]

Nope, but I heard the sound before and I am at least 70% confident after asking my ornitholog friend :-)

We don't have a huge load of animals making weird sounds around here, so one learns to recognize most of the strange ones after some years in the woods.