Urban Wildlife: Virginia Opossum

Nothing infuriates my Labrador retriever quite like a cheeky opossum (Didelphis virginiana) in the backyard, or a spooked one running off to hide under a shed or in a rocky embankment in the park. She will give chase if possible, but if the opossum turns to hiss and bare its teeth, she’ll beat a hasty retreat. Over the Christmas break, my Labbie was obsessed with the scent and pursuit of an unidentified critter in my parents’ suburban backyard; my father later trapped (and released in a wooded area along a bayou) the mystery animal, which turned out to be an opossum. That opossum fled each time my dog caught its scent and gave chase (I’ve never seen one “play possum”), and truth be told, her “encounter” with brisket and ham scraps, purloined from the garbage, was much more traumatic (and costly).

opossum

Opossum, pen sketch from my nature journal. Note that I remembered the species name incorrectly; D. marsupialis is found in Central and South America.

Opossums are nocturnal, and frequently encountered in suburban and urban areas of the US after sunset, and before dawn. This marsupial was introduced to the West Coast during the First Depression, perhaps as a food source (ugh), and has become well-established west of the Rockies, beyond its native range in the eastern US. In addition to the nuisances created by raiding garbage cans, household breaking and entering, roadkill messes, and skirmishes with dogs and cats, opossums can also harbor parasites that may cause human disease. Typhus-like rickettsiae (ELB agent) were found in the spleens of opossums in Los Angeles county, CA; opossum fleas were also infected with the ELB agent, or with Rickettsia typhi. The ELB agent, also identified in cat fleas, was thought to be responsible for mild cases of human murine typhus in the Los Angeles area (Williams et al., 1992). Infected cat fleas and opossums were confirmed to be probable reservoirs for the ELB agent, as well as an explanation for the persistence of human murine typhus in southern Texas (Schriefer et al., 1994). One in four opossums captured in urban areas of Caracas, Venezuela, was infected with trypanosomes, and these animals may be a primary reservoir for Trypanosoma cruzi, the causative agent of Chagas’ disease (Herrera and Urdaneta-Morales, 1992). Interestingly, opossums are fairly resistant to rabies infection, perhaps because of their lower body temperature.

chinaberries

Another common sight on suburban walks in this season: tallow tree berries

References:

Herrera L and Urdaneta-Morales S (1992) Didelphis marsupialis: a primary reservoir of Trypanosoma cruzi in urban areas of Caracas, Venezuela. Ann Trop Med Parasitol 86, 607-612.

Schriefer ME, Sacci JB, Taylor JP, et al. (1994) Murine typhus: updated roles of multiple urban components and a second typhuslike Rickettsia. J Med Entomol 31, 681-685.

Williams SG, Sacci JB, Schriefer ME, et al. (1992) Typhus and typhuslike rickettsiae associated with opossums and their fleas in Los Angeles County, California. J Clin Microbiol 30, 1758-1762.

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11 Responses to Urban Wildlife: Virginia Opossum

  1. Cath@VWXYNot? says:

    Hooray for the return of Kristi’s artwork to the blogosphere! I like the “FAT!” annotation too 🙂

    How big is a possum, by the way?

    I’m still new enough to North America to be enchanted by the native wildlife, especially raccoons, even when others regard them as vermin (and even when they keep trying to destroy our roof to nest in the attic. They’re still so cute! And my brother-in-law’s a roofer, so it’s all good).

    Raccoon tracks on our snowy lawn the other morning

    • KristiV says:

      The possums around here are usually between 1.5 to 2.5 feet from snout tip to base of the tail, and weigh about four to eight pounds, I’d guess. We have both raccoons and ringtailed cats in town, and the latter make the eeriest noises. I remember some visitors from Minnesota, who were camping in the Hill Country, and swore that they saw ringtailed lemurs near their campsite. No amount of explaining about the raccoon relatives would change their minds … they had seen LEMURS.

      Make sure the raccoons aren’t using your roof as a latrine. Your brother-in-law the roofer will likely know about that “charming” habit.

  2. ricardipus says:

    Raccoons *are* vermin, 100% fact. Bloody things. Their poo is also full of nasties – don’t let your cat near it.

    As for possums – well, they’re marsupials, which lends them some sort of cuteness mystique, at least to those who don’t have to deal with them raiding the garbage (cf. “raccoon”, above). But they look a bit too much like rats for my liking.

    Oh, and +1 vote for Kristi artwork. w00t!

    • KristiV says:

      @ ricardipus – Thanks! And you’re absolutely correct about the vermin classification. Dogs definitely, and maybe cats (I don’t know), can contract diseases from exposure to raccoon poo, the nastiest of which is pancreatitis. I don’t think they even have to eat the poo to get sick … just the rain runoff from a roof latrine can carry the pathogens IIRC.

      I yelled at a couple of raccoons on my roof once, and they both strolled down to the edge and gave me that “You talkin’ to ME?!?!?” look. Same look the horses give me when I chastise them for picking up and tossing the brushes and other grooming items off the shelves in the barn breezeway. Good thing I don’t have kids – I get no respect as a disciplinarian.

      • Cath@VWXYNot? says:

        Hmm, didn’t know that. Thanks for the info – I’ll ask Mr E Man or his brother to check the roof.

        My sister-in-law recently had to throw away all of her highschool year books because a pregnant raccoon broke into her toolshed and had babies all over them. (She let the babies grow up a bit before evicting the family). But raccoons are the least of her worries: last time I was over there, one panel of her fence was missing. I asked what happened, and it turns out a bear had burst through it one evening while her husband was outside BBQing steaks. (He ran straight inside, but she sent him back out to rescue their dinner – apparently the bear wasn’t interested in the steaks, because it was running away from an angry fruit tree owner).

        I <3 Canada.

  3. Steve Caplan says:

    When I lived in Rockville, Maryland, I used to see a really fat opossum nonchalantly munching away just outside the White Flint Metro station. Here in Nebraska I have not seen any, though we sometimes get wild turkey scampering through our backyard.

  4. Stephen says:

    Late again but:what Cath said. Lovely to see your artwork back on the blog. I am so envious of your talent.

  5. Heather says:

    As one used to say in the neighborhood in which I grew up, Psych! I’m so glad you’ve come over to the dark side, too. Yay.