Hi Netty,
Whatever it is, you not only need to get it out of there, but you need to have ALL and EVERY INCH OF ELECTRIC WIRE INSPECTED!! Neighbors of ours had squirrels in their attic and removed them. Two years later the house caught on fire in the attic and destroyed half the house. Had it not been for smoke detectors, the family would have perished, as the fire started in the middle of the night.
It took two years for the wires to heat enough to cause the fire. The fire department determined it was from the squirrels chewing on the insulation that covers the wires. Mice will do the same thing.
Newt