Seems to me that any animal seen as being powerful, especially if its power is associated with nature/fertility/the gods can be seen as either good or bad luck, depending on which side of the coin you look at (which facet of the belief survives through the generations).

I remember reading somewhere (forget where) that the supstitions we have about black cats originated with black rabbits (as cats were not native to Europe, until sailors broght them back aboard ships from the middle east).

Here, in America, black cats are seen as bad luck/evil. This fear runs so deep that many humane shelters won't adopt out any black cats around Halloween for fear that they'll be abused/tortured.

But in Britian, as I understand it, black cats are considered to be good luck.

Many years ago, I read (perhaps in the same place where I read about the rabbit/cat switch) that both these beliefs originate in Ancient Rome, where the black rabbit was seen as a companion of the Goddess Hecate, who was the goddess of the crossroads, as well as goddess of witchcraft. If you saw a black rabbit (or black cat) going along the road in the same direction you were traveling, that was a sign from the goddess that you were headed for good fortune, but if the rabbit crossed your path, that meant there was danger further down the road.

In Britain, they remember the first half of that belief, and in America, we remember the second half (which, if you ask me, is like blaming stop signs for car crashes).

But, to reiterate the opening question in this thread: "What's the musical connection, here?"