But the forms which enter into and go out of nature are the likenesses of eternal realities modeled after their patterns in a wonderful and mysterious manner. Identification can be a puzzle, but it's a puzzle that birders love to work on. Actually, the concept of species is something of a puzzle in itself.
Ornithologists argue at length and with surprising heat about what the word means.
It's odd, because it is such a common sense, everyday notion, that everybody knows fairly well what a species is. And everybody knows that all birds belong to one species or another. It's true, sometimes the birds don't look exactly like the pictures. The color can be disguised by strong back lighting. The shape can be misleading if the bird is viewed from an odd angle.