For superstitious people, it means "bad luck". For the rest, it is just another cat.
It probably means that the bird was caught by a cat.
The cat
A highly advantaged position.
The character Sylvester on the Disney cartoon, LOONEY TINUES, is the black and white spotted cat, that always tries to eat the yellow bird named, "Tweety Bird." But, Sylvester usually gets in trouble for trying to eat the yellow bird named, "Tweety Bird."
Having a black cat on your shoulder can mean a couple of things. One meaning is that it is good luck.
do you mean,its bad luck when a black cat crosses you at night?
" Remove or cancel, " said Thunder
Necromacers use cat skulls in black magic. These cat skulls are said to provide more power to the practitioner of these black arts.
The superstition is your in for bad luck if a black cat crosses your path.
If you mean any black cat's eyes, then they are usually greenish.I hope that is what you meant. If it isn't, then sorry.
If you have a boy cat, that probably means that she has mated with your cat.