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Posts Tagged ‘Virginia opossum’

I hate biology by Facebook meme. We’re living in a time of great natural history illiteracy, but we’re also living at a time in which people want to respect and learn about nature.

Virginia opossums are one of the most common species in the United States. They fit nicely in suburbia, and they are quite often encountered.

They are not cute, at least by conventional standards of cuteness, and when you encounter them, they stand with their mouths open in a gape threat display. They usually drool and generally look nasty.

So well-meaning people have tried to make the opossum look good, and in doing so, they have decided to bullshit people.

Bullshitting about any animal is a bad conservation strategy.

One common statement is that “many studies” or “a study” have shown that opossums are smarter than dogs and cats.

I had to hunt to find that citation! You’d think that such a groundbreaking discovery would be all over the clickbait science press, but no, it’s actually rather obscure study.

It was a study that was performed in the 1950s using the Fink arrow maze. It is really just a test to see if an animal can remember where it was fed before.  The researcher who did the research was a W.T. James, and he performed some other studies on the species, which did not show such a marked ability among the opossums. They are capable of learning.

Other researchers looked into the opossum’s intelligence and have generally found it lacking. Indeed, a 1965 study revealed that opossums were much worse than rats at learning how to follow a maze.

The 1950s study is the only one that compared dogs and opossums, and we live in a time in which a new cognitive study on dogs is released every month or so. Dogs are pretty intelligent animals. They have evolved some cognitive shortcuts that have allowed them to live in close concert with humans and to learn from humans.

So you have one study that shows opossums are more intelligent than dogs and you think that is worth posting on a Facebook meme?

It’s bullshitting people.

The truth is opossums don’t have to be smart to be successful. What makes them successful are two simple things: they reproduce rapidly and they will eat virtually anything.

They also can live their whole lives next to people and never really bother anything. Opossums are far less obnoxious to have around than raccoons are.  Raccoons tear things up. They open up garbage bins. They den in chimneys. They kill cats and eat their food.

A raccoon is an intelligent animal. They know how to open up chicken coops and eat all the chickens. They know how to open up gates and get into cornfields.

An opossum will just trundle around and not cause too much trouble.

It works for them.

And yes, they eat ticks and can prevent the spread of Lyme disease.

But they aren’t smarter than super social carnivorans.

So when you see these memes posted on Facebook about how wonderful opossums are, keep in mind that the claim about opossum intelligence being greater than dogs comes from a single study.

It’s bullshitting people. This study is useful, but it’s 60 years old. And no one has attempted to replicate it or tried to draw deeper meaning in the general comparison of cognitive abilities between dogs and opossums.

So yeah, one study. Interesting discovery, but it hasn’t been replicated. Also it doesn’t match what else we know about the two species.

It’s just one of those things you run across in a literature review and wonder about.

A much better understanding of opossums is they are primitive mammals. I don’t mean that they are inferior in this sense. I mean that they very similar to the first mammals that ever existed, and they have retained these primitive, generalized traits for tens of millions years.

That’s pretty amazing.

And it’s not bullshitting people.

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yapok

The yapok or water opossum is a marsupial that ranges into Mexico and Central America.

Americans are an unusually insular sort of people. We fail at geography big time. Don’t ask the average American what the capital of Canada is.  Don’t tell tell us that Mexico City is the largest city on the continent.

“Because Mexico ain’t on our continent!”

That attitude even affects how we view nature.

When I was a little boy, I accepted without any question that North America’s only marsupial is the Virginia opossum.

It seems this claim is so widely-accepted that it is usually mentioned within the first sentence of any description of the species.

There is, of course, a big problem with this description. North America isn’t just the US and Canada.

This is North America:

North America

Yes. All that territory from Mexico to Panama is part of North America, and in those countries, there are multiple species of marsupials. Central America has 11 species. Mexico alone has has 8!

It is correct to say that the only marsupial in the US and Canada is the Virginia opossum, but it is geographical ignorance that only an American could conjure that says the Virginia opossum is the only marsupial found on the continent.

So when you see someone saying that Virginia opossums are the sole representatives of marsupials on this continent, realize that this person hasn’t thought through what he or she is actually saying.

Or is totally unaware that there isn’t continent between “North America” and South America.

There is also a subconscious racism at work, which sees only a community with Anglo-America as the true North America and casts aside that which lies to our south as being the other.

It may all be a silly little thing, but it grinds my gears.

And when we write about nature, we need to be more careful with our language.

 

 

 

 

 

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This week we had several visitors on the trail cameras. Keep in mind that one of these cameras has a messed up clock, so the time stamp reads that the video was taken in 2068. These cameras are pretty good technology, but they aren’t that good!

Let’s start small.  Here’s a white-footed mouse or a deer mouse:

Source.

I can’t tell whether it is a white-footed mouse or a deer mouse, which is hard enough to do in the broad daylight. These animals are in the genus Peromyscus, and although we call them mice, they aren’t closely related to the mice that originated in Old World.  New World rats and mice are more closely related to voles, hamsters, and lemmings than to house mice and Norway rats.

Then we got a light-colored opossum:

Source.

A good close-up of a melanistic gray squirrel:

Source.

And a large raccoon:

Source.

Because of the size of the raccoon, I am assuming that this one was a male. He was coming to inspect a pile of sticks and logs that I have anointed with weasel lure.

 

 

 

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Got this ‘possum in cage

It’s a little female Virginia opossum.

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The much ballyhooed prehensile tail:

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Old opossum

old opossom

I get opossums on the trail camera fairly regularly, and because I find them somewhat less interesting than other animals, I usually don’t post their photos on here.

This one, however, is kind of interesting because it has the features of a very mature individual. Now, keep in mind that Virginia opossums don’t live very long, even though they are about the size of a domestic cat. In captivity, their record longevity is a measly four years.

But this individual is at least on its second year.  The frostbitten ears suggest that it has survived more than couple of very hard freezes.

As opossums mature, they get a lumpy head profile.  When they are younger, they have a more collie- or borzoi-like head, but as they get up in years, this starts to change.

This opossum is the most primitive mammal north of the Rio Grande, and when I say this, I don’t mean that it’s primitive because it’s a marsupial. It’s actually a primitive marsupial, meaning that it looks very much like the earliest mammals that gave rise to all marsupials. Indeed, it is so primitive that the similarities between New World opossums and the West Indian solenodons are pretty striking. The two species of solenodon retain many primitive features of the ancestral placental mammals, and it would make sense that the primitive opossums and primitive solenodons would look somewhat similar to each other.

Beyond their taxonomy, there aren’t really that many amazing things about opossums. They don’t have very complex behavior.  There are claims of them having amazing intelligence that one can find online, but these clams are not born out in reality.

The thing is, you don’t have to be too smart if you can eat just about anything and reproduce by having dozens of offspring every year.

And even though they are primitive, natural selection has still worked its ways on their kind, but it’s just not change them as much as it has us, coyotes, or red kangaroos.

 

 

 

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An old opossum

This old opossum is a survivor. It looks like it even has a bit of frost bite on the ears from last winter.

old opossum 

old opossum I

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One ugly barn cat

Source.

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