Best practices for nuisance wildlife control operators in New York State

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Appendix B: Control tips for common nuisance species in New York

Opossum (Didelphis virginiana)

North America's only marsupial (mammals whose young develop in a pouch). They're more closely related to kangaroos and koalas than to the other animals in the neighborhood!

Opossum

Size:

4–14 pounds. Body is 15–20 inches long. They often suffer frostbite and lose part of their tails and ears.

Signs of their presence:

1. Sounds: growl, hiss, screech when threatened.
    
2. 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.
    

3. Tracks

   Scats

   Tracks: look like they were made by little human hands, fingers spread wide apart.
    
4. 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.

Diet:

Opportunist. Opossums eat mostly meat (mainly insects or carrion) but they also eat many plants, especially fruits and grains. They may eat garbage, compost, pet food, bird seed, bird eggs, and young birds (turkeys, chickens, geese, and game birds). They also eat voles, shrews, worms, and toads.

Typical activity patterns:

Social style: Solitary.

Daily activity: Usually nocturnal.

Hibernator? No, but does den up for days at a time when the weather is bad.

Migrates? No.

Where found:

Distribution in NY and the Northeast: rural, suburban, and urban areas; parks.

Habitat: Wide ranging—arid to moist, woodsy to open, but more common near streams and swamps. Dens in a different place three out of four nights (except in the cold of winter). They find shelter under buildings, in brush heaps, hollow logs or trees, old crow or squirrel nests, and rock crevices. Opossums may share quarters with woodchucks, skunks, and rabbits.

Territory and home range: not territorial. They have constantly shifting home ranges and may be considered nomadic. Home range is usually 10–50 acres.

Breeding habits:

Pair bonding style: Polygamous. Females raise the young alone.

Breeding dates: February–June. Most females, though, have just 1–2 litters per year. The young are born about 13 days after breeding.

Litter size: 6–16, average 8.

Life in a pouch: The tiny (about 1/2" long) young are born blind and helpless. They must crawl into the mother's pouch and attach to a nipple. They'll remain in the pouch for 7–8 weeks, firmly attached to that nipple. Then, for about two weeks, they'll begin to explore the world, often riding on the mother's back. They'll return to her pouch to nurse. They're weaned at about 3 months old and are generally fully independent by the time they're seven inches long.

Amount of time young remain with parents beyond weaning date: 3–4 weeks.

Common nuisance situations:

Time of year: Any time of year.

What are they doing?

1. Raid gardens, chicken coops, bird feeders, pet food, and garbage.
    
2. Sometimes den in garages or attics and make a mess.
    
3. 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.
    
4. Disease risks to people: mange, rabies (rarely).

De-bunking myths about opossums:

1. A hissing or drooling opossum is not necessarily rabid. When threatened, a healthy opossum may bare its teeth, make a lot of noise, drool, bite, or leak a nasty fluid out of its rear. Stress may cause them to play dead, which might confuse predators and keep them from being eaten.

Legal status in New York:

Protected. Game species with set season. From ECL 11-0523:

"7. Whenever black, grey and fox squirrels, opossums or weasels are injuring property on occupied farms or lands or dwellings, they may be taken at any time in any manner, by the owners or occupants thereof or by a person authorized in writing by such owner or occupant.

 9. Varying hares, cottontail rabbits, skunks, black, grey and fox squirrels, raccoons, opossums or weasels taken pursuant to this section in the closed season or in a manner not permitted by section 11-0901 shall be immediately buried or cremated. No person shall possess or traffic in such skunks or raccoons or the pelts thereof or in such varying hares or cottontail rabbits or the flesh thereof."

Best practices

Relax:

1. Opossums move around a lot, and usually don't stay in one den site. If the problem was caused by an individual opossum, it will probably leave on its own. Just realize that the problem could be caused by different animals who are all attracted by the same source of food, water, or shelter.

Remove food sources and shelter:

1. Put trash out in morning instead of the evening.
    
2. Opossum-proof garbage can with a tight fitting lid, or secure it with straps.
    
3. Don't leave pet food out at night.
    
4. Enclose compost piles in a framed box using hardware cloth; in a sturdy container, such as a 55-gallon drum; or in a commercial composter.
    
5. Keep the area under bird feeders clean.
    
6. Remove brush piles and debris.
    
7. Close garage doors at night.

Protect vulnerable livestock:

1. Close doors to poultry houses, and if birds are caged, keep those doors closed, too.
    
2. To keep opossums from climbing over a wire mesh fence, install a tightly stretched electric wire near the top of the fence, about 3" out from the mesh.
    
3. Install an electric fence around the hen house, or use hardware cloth to cover holes and potential entrances.

Trapping strategies:

Live traps:

1. Opossums are easily caught with cage traps.
    
2. Foothold traps (# 1 or #1 1/2) are also effective.
    
3. Set traps along fence rows or trailways in a dirt hole, cubby, or running pole set.
    
4. They prefer slightly spoiled baits, such as cheese or fruit. If you use a box trap with these baits, you may also capture skunks so be prepared to release them.
    
5. They're slow, so it's possible to capture them by hand, or with the use of a catchpole. Grasp the end of the tail (wear heavy gloves because they have sharp teeth). If you're holding an opossum and it tries to climb its tail to reach (and bite) your hand, lower it to the ground, where it will attempt to crawl away.
    
6. Assume that a female opossum has young in her pouch during the rearing season (March–August). The females are not likely to retrieve young, so make sure that all her babies are either in her pouch or clinging to her before you release her.

Lethal traps:

1. Body-gripping trap, #120 or #160, set in a vertical cubby for greater selectivity (see chapter five for details).

Preferred killing methods:

1. CO₂ chamber
    
2. Lethal trap
    
3. Lethal injection of barbiturate, if possible
    
4. Shooting, using a shotgun with #6 shot or larger, or a .22 caliber rifle (heart/lungs shot is preferred). Why is just the heart/lungs shot listed as preferred? The head shot is difficult because opossums have very small brains located in a relatively large skull—and there's a strong crest on their skull, which can deflect the bullet. See the illustrations on the next page for more information about the head shot.
   
   Properly targeting a head shot for an opossum is challenging because their brains are much smaller than you'd guess, looking at the size of their heads. Looking at the side of the opossum's head, imagine a direct line between the eye and ear. Now, aim slightly below that, closer to the base of the ear. Position the gun very close to the head.

Acceptable killing methods:

1. Gunshot to the head (this is a difficult target and should only be attempted by NWCOs who are more experienced and skilled in the use of firearms)
    
2. Stunning and chest compression
    
3. Stunning and exsanguination

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