Is there a bird in Massachusetts so obscure that even the bird guy hasn’t heard of it? No – don’t be ridiculous. But there is a species that nests on the Cape and Islands that is so rare, so poorly understood, and so mysterious in its habits that even ornithologists don’t know what their status is. And a tantalizing recent sighting, or, more correctly, “hearing” of this species has me wondering whether there may be more around than we realize.