Um, if a bird wouldn't see for instance blue and Superman is just wearing his blue suit sans cape, the bird would see a white *) suit. It's the same as if a surface would only reflects UV-light, for instance. The object does not become invisible **)
Michael
*) IIRC, but could be black if I got it exactly the other way around.
**) Unless it's in the Superman universe, where such a suit would in fact make you invisible until sprinkled with phosphor.
