Opossum (Didelphis virginiana)
North America’s only marsupial (mammals whose young develop in a pouch).

Size: 4–14 pounds; Body is 15–20 inches long.
Often suffer frostbite and lose part of their tails and ears.

Signs of their presence:

Sounds: growl, hiss, screech when threatened.

Evidence of their feeding: Eggs that have been chewed into many small pieces. (Raccoons usually remove one end of the shell without crushing it. Foxes carry eggs away. Weasels and mink crush the entire egg.) Opossums maul chickens beginning at the rear, while raccoons bite their heads off.

Tracks: look like they were made by little human hands, fingers spread wide apart.

Scats: are semi-liquid and don’t last long. Left everywhere, even in the den. When scared, possums may secrete a smelly, greenish fluid out of their butts.

Common nuisance situations:

Time of year: Any time of year.
Raid gardens, chicken coops, bird feeders, pet food, and garbage.

Sometimes den in garages or attics and make a mess.

A parasite found in the feces of opossums can contaminate water and food sources for horses (both hay and feed). This parasite can transmit a disease to horses, called “equine protozoal myelitis.” This disease affects the nervous system and can cause lameness.

Disease risks to people: mange, rabies (rarely).
For more information:
http://www.nwco.net/08-AppendixBNuisanceSpecies/8-07-Opossum.asp