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Archive for the ‘Rodents’ Category

I saw this while out on the Coyote Highway:

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You’ll not see another rodent with a skull like this.

All other rodents known to science have chisel-shaped incisors that meet in the front. These teeth grow continuously, and their continuous grinding keeps them sharp and pointed.

All other rodents know to science have molars for grinding down food.

This rodent has neither of these features.

This all sounds bizarre, but this skull belongs to a new species of rat that was discovered on the Indonesian island of Sulawesi.

This animal was just described to science yesterday in the journal Biology Letters.

If one looks closely at the skull, one can see that it has no molars– at all.

This is very weird for a rodent.

It has incisors. The bottom incisors look very much like those of normal rodents, chisel-shaped, but the top incisors are little fangs.

This new species captured by a team of researchers who set up “pitfall traps”– buried buckets that are level with ground that allow small animals to fall in.

The researchers caught two of them, but they didn’t know until they examined the skull of a dead specimen that they had such weird dentition.

These rats live in high-elevation forests that are covered in moss.

The rats have evolved to live entirely on earthworms.

Earthworms aren’t very hard, so the rats have lost their rodent dentition.

Their teeth are now “worm grabbers.”

Their only purpose is to catch the worm, when the rat sucks it out of the ground with its long muzzle.

The species has been give the name Paucidentomys vermidax. Paucidentomys means “few-toothed mouse,” and verimdax means “worm-eater.”

This new species, which has not yet been given a common name, is closely related to the shrew rats that are found only on Sulawesi and the Philippines. Indeed, this animal is itself a new species of shrew rat. Shrew rats are largely insectivorous in their diet. They still have the typical rodent dentition. They have simply evolved into the shrew’s ecological niche.

This one, however, has become quite specialized to eating only worms.

It’s really unique among all rodents.

No other species of rodent has evolved such bizarre dentition to accommodate such a specialized diet.

Evolution produces lots of bizarre things.

But this is one of the most bizarre.

From a lineage that has produced the most diverse and successful order of mammals on the planet largely through its peculiar dentition, a species has evolved that has totally lost that defining characteristic of its order.

No longer can we say that all rodents have grinding incisors and molars.

We can only say all rodents but one.

And that’s this little shrew-like creature from Sulawesi.

The few-toothed, worm-eating mouse!

 

 

 

 

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Northern and southern flying squirrels are interfertile species. I did not know this.

And just as the coyote is a major threat to the red wolf through hybridization, the southern flying squirrel is a threat to the northern species.

West Virginia has a unique subspecies of the northern flying squirrel called the Virginia northern flying squirrel. It is native to the forests of the High Alleghenies.

Now, when I was growing up, I once shared my bedroom with a small colony of southern flying squirrels.  To save them, I made the claim that these were the endangered Virginia northern flying squirrels.

Of course, they weren’t.

 

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White Chipmunk

Source.

Don’t ask me what species of chipmunk this is.

I am accustomed to a single species of chipmunk (the Eastern), and this species seems to be the one most commonly offered as an exotic pet.

So it’s most likely an Eastern chipmunk.

I’ve seen zillions (only a slight exaggeration) of Eastern chipmunks. I also had a few as pets, which we caught in live traps near the old chestnut tree. Even the wild caught ones do tame down.

I’m sure keeping wild chipmunks as pets is now illegal.

Which is just as well.

I love listening to their little popping and trilling sounds as the forage through the undergrowth on a crisp October day. I also enjoy watching them visit the squirrel feeders to fill little cheek pouches with corn.

The weekend before last, I was in Gettysburg. Standing at the summit of Little Round Top, I saw something dart across a boulder. When my eyes focused on the moving object, I saw it was a little Eastern chipmunk.

Of all the things I could have been looking at, I was watching these little chipmunk dart back and forth. ( Of course, it didn’t hurt that this wasn’t my first trip to that battlefield.)

But it was the normal coloration. It wasn’t a white one.

If it had been, I’m sure it would have drawn lots of attention.

I’m also sure that someone would suggest that it was one of Gettysburg’s ghosts.

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southern flying squirrel

I was in deep slumber when it happened, but the sensation of very soft fur and tiny claws scurrying across my face certainly woke me up. Indeed, not only was I up, but I was out of the bed and nearly out the door. Then it crossed my mind to turn on the lights and see what creature had disturbed my sleep.

Whatever the heck it was it, it was brave enough to crawl into bed with a person. At the time, I was but an adolescent, so my imagination was running wild.  My room was just below the attic, and the thought crossed my mind that a bat had crawled down to find a warmer place to roost. I was not too keen on sharing my bed with a bat, for in my part of the world, there is a bat-born strain of the rabies virus.

I knew the furry animal was too large to be a mouse.  A few summers earlier I had seen my grandpa’s Norwegian elkhound kill some rats in a barn. Maybe the creature was a rat.

My curiosity drew me towards the light switch, but when I turned it on, nothing was there. I sifted through my sheets and pillows, but nothing turned up. I looked under my bed and other bedroom furniture. Nothing.

Then the thought crossed my mind to look up. My room had several rafters running parallel across the ceiling. Maybe the creature had run to the ceiling to escape.

I saw a small gray blob hanging from one of the rafters. It was larger than a bat, but much smaller than any rat. It was roughly the size of a lemon.

Then I noticed that the blob had large black eyes and elfin ears.  By then I had already developed into a something of amateur naturalist, and I knew what had woken me. It was a southern flying squirrel.

I don’t know why I screamed at that moment, but I did anyway. Maybe I was terrified that such a creature could intrude into my space while I was sleeping. After all, I was not immune to delusion that I, as a human, had absolute control over all nature.

My parents were in the room in a instant, and my father turned and ran into the kitchen. He returned with a broom.

He then did what many men do when they discover an unwanted rodent in the house. He decided to kill it with a broom. However, flying squirrels are far more agile than any rat or mouse, and within just a few second it had escaped back into the attic through a very small crack in the ceiling.

Well, there was no point in digging through the attic at that hour, so the squirrel had escaped that night.

In the morning, my father brought in a rabbit trap. A few summers before, we had rabbit trouble. The cottontails had eaten up most of the beans, and the problem was remedied using a live box trap, which was baited with an apple.

The trap was placed in the attic and baited with popcorn.

It was late that night when I heard the door on the trap slam shut.

The little pixie who had woken me from my slumber had been caught.

The next evening, the trap was taken to the hillside behind my house, where there were several large hickory and oak trees. A maple tree at the corner of the lawn had a large bird house, which, I had surmised, was perfect home for a flying squirrel. The squirrel was set free at the base of one of the hickories, and he scurried up the tree. He nearly reach the top, when I saw him glide. It was the first time I’d ever seen one glide, and it was quite impressive.

However, instead of gliding up the hill and deeper into the forest, his route was down hill and towards the house. He landed in one the maples at the edge of the yard, then sailed off towards another one and another, until he was in a tree very close the the house.  He then glided on the roof, where I assume he disappeared into the attic.

He’d returned home.

I was willing to let him stay.

For a few months, he often visited me in my room, running across the rafters at night, making just enough noise to wake me up.  He never again got in bed with me. However, one night, I felt some warm liquid dropping on my forehead, and I soon realized that my little friend had urinated on me.  To say the least, I was not too happy about that.

Well, it wasn’t long before my little friend told all of his friends about our attic, and by the end of that year, we had at least a dozen flying squirrels in our attic.

And then my dad started trapping them– with rat traps. I wasn’t happy with that, but they were eating up all the things we had the attic. Our Christmas decorations were being mutilated, and the wires to our Christmas lights were in shreds.

To try and change his mind about killing them, I had discovered that there was an endangered species of flying squirrel in West Virginia. The Virginia northern flying squirrel was, until recently, listed on the Endangered Species list. Now, the northern and southern species of flying squirrel are very similar, but the northern species is found mostly in Canada and the northern tier of states. The Virginia subspecies is an isolated population that lives in the High Alleghenies. I grew up in the Allegheny Plateau region, not the mountains proper, so the species in my attic was the southern.

After a few weeks of intensive rat trapping, the squirrels were all gone– or so I thought. Then one night I heard a scurrying sound, and I looked up at the rafters. Just a few inches from the crack in the ceiling, a flying squirrel was hanging upside down. In its mouth was something pink.

The pink thing had what appeared to be translucent wings hanging down from its sides. When I looked closer, I realized that this was a flying squirrel mother carrying her newborn baby. The baby was quite small and pink like a baby mouse or hamster, but unlike those animals, it had distinctive little membranes hanging off of it. These were the sails of the flying squirrel.

The mother squirrel carried her baby across the ceiling, and then she turned around and went back through the crack into the attic. I never saw her or her baby again.

In fact, shortly after that, all the outside cracks around the roof leading to the attic were sealed, and no flying squirrel would ever enter the attic again.

And none would ever come into my bed again.

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The Guinea pig is a popular first pet for many children, but the identity of its wild ancestor remains unclear.The Guinea pig is a popular first pet for many children, but the identity of its wild ancestor remains unclear.

The familiar Guinea pig has long been a first choice for parents seeking a first pet for their children. The species is known for is rather placid temperament and relative ease in its husbandry.  It comes in several different coat types, which vary from the long-haired Peruvian to rough-haired Abyssinian to the completely hairless Baldwin, and a wide array of colors, including tortoiseshell and brindle varieties.

However, unlike most domestic animals, we are still unsure of the Guinea pig’s ancestor.  We have several candidates, but it is possible that the domestic Guinea pig’s ancestor is an unknown species.  So let’s explore the candidates.

First of all, in case you didn’t know, Guinea pigs have a totally false name. They are not from any country known today or historically as Guinea, including the island of New Guinea. They also are not swine. They are hystricomorph rodents, and the Guinea pigs and the various South American relatives, including the capybaras, pacas, agoutis, and maras, are considered in infraorder Caviomorpha. The cavies make up a specific group  in the Caviomorpha infraorder, and these things vary greatly in appearance. The most famous of these is the Guinea pig, but the capybara is also pretty well known. The capybara is a giant cavy that lives a semi-aquatic lifestyle. My personal favorite of the cavies of is the mara, which looks like a cross between a Guinea pig, a hare, and an antelope. However, also included in this cavy group are several nondescript rodents that could be the ancestor of the domestic Guinea pig.

The Brazilian cavy (Cavia aperea) is sometimes considered the Guinea pig’s ancestor. It can produce fertile offspring if hybridized with the domestic Guina pig, but after several generations, fertility becomes an issue. Because fertility does not continue through the generations, it is likely the the Brazilian cavy is just a very close relative of the Guinea pig and not its immediate ancestor.

The Shiny Guinea pig (Cavia fulgida) might be an ancestor, but it leaves in Eastern Brazil, which is quite far from where we know that the Guinea pig originated, which is the highlands of Ecuador and Peru.

The Montane Guinea pig or the Tschudi’s cavy (Cavia tschudii) seems to be a more likely ancestor. It is native to the same regions where we know the domestic Guinea pig originated. However, studies of the biochemistry of this cavy and the domestic Guinea pig suggest that they are not the same species. Thus, Tschudi’s cavy is probably not species we are looking for.

Tschudi's cavy

Tschudi's cavy

Things do get somewhat confusing because in some parts of Peru, Ecuador, and Bolivia, Guinea pigs are very common as domestic animals. Feral populations of these animals can be found, and it can be difficult to determine whether one is looking at a true wild cavy of a different species or an unsusually pigmented feral Guinea pig. For example, one of the first specimens of Tschudi’s cavy that was sent to Europe appeared to be an agouti pigmented domestic Guinea pig. Further, there is a documented cavy near Bogotá, Colombia, called Cavia anolaimae. It is said to be very similar to the domestic Guinea pig, but it often considered to be nothing more than a feral Guinea pig. Another unusual Guinea pig (Cavia guianae) has been documented in northern Brazil, southern Venezuela, and Guyana. It is not clear whether this is also a feral population of domestic Guinea pig, a population of Brazilian cavy, or a new species, which could be the Guinea pig’s ancestor.

However, it is possible that these anomalous cavies are actual the ancestral Guinea pigs. Perhaps through regular hybridization with domestic Guinea pigs that the wild populations of these animals became severely reduced. After all, the parts of South America where the Guinea pig was first domesticated have gone through great upheavals through conquest, civil wars, and other strife. As a result, it is likely that domestic Guinea pigs, where were kept so closely to their villages as a food source escaped into the wild. There, they hybridized with the wild ancestral Guinea pig, whatever it is or was, and then polluted its gene pool until it disappeared through hybridization. This theory is the one I think more likely, but it’s just as possible that the unsual Guinea pig-like rodent sent back with the first Tschudi’s cavy was one of these wild Guinea pigs. It’s also possible that the unsual cavies that are called  Cavia guianae and Cavia anolaimae are relict populations of this wild cavy that is the ancestor of the domestic Guinea pig.

It is hard to believe that we know very little about the domestic Guinea pig’s ancestry. We know what its closest relatives are, but so far, none of them are thought to be their direct wild ancestor. Maybe someone will do an in depth analysis of Guinea pig and wild cavy molecular evolution, which will lead us to the answer. Right now, all we can do is speculate.

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Watch this video.

The presentation is by Jonathan Downes, director of the Centre for Fortean Zoology.

I pretty much agree with his theory that some of the victims were actual victims of mongoose predation. Puerto Rico does have some small Indian mongooses.  The ants then removed their livers which contained most of their blood.

However, his theory about the porcupine, I cannot exactly accept. There once was a pallid hairy dwarf porcupine or Lesser Antillean porcupine. These are short-squilled New World porcupines, and they aren’t as closely related to the Hodgson’s porcupine of Hong Kong.

The palid hairy dwarf porcupine was similar to this Mexican hairy dwarf porcupine--short spined and highly arboreal.

The palid hairy dwarf porcupine was similar to this Mexican hairy dwarf porcupine--short spined and highly arboreal.

The Hodgsons is now classified with the Himalayan or Malayan species. It does have that destinctly spiky appearance with long barbs coming off its back. It lacks the typical crest of most Old World porcupine species.

hystrix-brachyura

The evolution of similar features on New World and Old World porcupines is a good example of parallel evolution.  The ancestors of both of these types of porcupines were related, but the two evolved their quills through different experiences with natural selection.

Now, what do I think could be taking down the banana trees in Puerto Rico?

Most islands in the West Indies have a native rodent on them called hutias. These are relatively large creatures that could possibly take down a banana tree.

Demarest's hutia is native to Cuba. It can weigh 15 to 20 pounds.

Demarest's hutia is native to Cuba. It can weigh 15 to 20 pounds.

Now, Puerto Rico officially has no hutia species living on it. Historically, it has had at least two different species. One was evident during the early days of colonization until about ten years ago. It was called the Puerto Rican hutia, but it was also found on Hispaniola (Dominican Republic and Haiti). It officially went extinct in the 1990’s, so it is very possible that a relic population of Puerto Rican hutias still exists on the island.

The other species of hutia native to Puerto Rico was the Puerto Rican giant hutia. It went extinct following the last Pleistocene. Its maximum weight was over 400 pounds. I somehow doubt that this is the species of hutia that’s tearing down the banana trees.

Now what about the spiky appearance?

Well, look at this Hispaniolan hutia. This is the closest relative of the Puerto Rican species, and it has a kind of spiky appearance on its back. Its shaggy hairy looks a little bit like a porcupine.

Further, this Cuban hutia has a somewhat spiky appearance. If this species got wet, I bet it would look even spikier.

cuban-gray-hutia

Not only that, American soldiers stationed at Guatanamo, Cuba, have a name for the Cuban  or Demarest’s hutia. They call them “Cuban banana rats.”

However, they don’t normally eat bananas. Their fecal matter is in the shape of a banana. However, they do eat fruit.

So it is very possible that the Puerto Rican hutia is alive and raiding the banana plantations, and that species could be the spiked rodent.  Or it could be another species of hutia that is currently unknown to science.

Mr. Downes has a very rational explanation of the chupacabra phenomenon. I am skeptical of an extant long-quilled porcupine in Puerto Rico, but I think the hutia hypothesis is worth considering.

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