Tag Archives: shrew

The Somali sengi, a tiny cousin of the elephant, makes a reappearance after 50 years

The Somali sengi (Galegeeska revoilii), a tiny member of the elephant shrew family, has been considered extinct for the last 50 years. However, new sightings in Somalia and Djibouti show that the species isn’t lost after all.

Image via Wikimedia.

NPR reports that the shrew has made a comeback in both countries after more than half a century of absence — the last official record of one being spotted comes from 1968. Even more impressive is that the species isn’t native to the country of Djibouti.

Small but kicking

“It’s a teeny, tiny relative of an aardvark and an elephant that’s the size of a mouse,” Steven Heritage, a researcher from Duke University who has been looking for the creature, told NPR.

“We know now that it is for sure a rock-dwelling Sengi. We know that it has foot-drumming behavior as one of its communication behaviors. So we have some basic knowledge now.”

Being considered extinct for such a long time means that researchers don’t really know a lot about the species. With its reappearance, however, that lack of understanding might be addressed — as well as the questions regarding how this species stayed hidden for so long.

While the spotting is definitely good news for the species — it can’t be extinct yet if it’s right there — we have no idea of the health of the species. Without reliable population figures, we simply can’t know if the shrew is, in fact, on the verge of disappearing completely. Being spotted outside of its native range is definitely encouraging, but not enough on its own to point to a recovery.

What we do know is that the shrew is good at keeping a low profile. So in the future, researchers will need to be extra crafty in order to gain accurate data on the shrews’ health, habits, and dietary preferences. From there, they can piece together a snapshot of their entire species’s health, and decide whether conservation efforts are needed to keep it from going extinct.

Shrew-transmitted Borna virus linked to killer brain infections

Rubbenstroth D, Schlottau K, Schwemmle M, Rissland J, Beer M (2019) Human bornavirus research: Back on track! PLoS Pathog 15(8): e1007873.

In a recent Lancet Infectious Diseases publication, researchers describe eight human fatalities in Germany caused by Borna disease virus 1 (BoDV-1) and suggest that wider testing for the disease may be useful in regions where the virus occurs in the wild.

The study was based on data collected from the brain tissue of 56 patients who died of an unidentified virus and presented with encephalitis (inflammation of the brain). Six of those patients had BoDV-1, and two were likely infected. The newly confirmed cases raise the number of published BoDV-1 deaths in the endemic area to 14.

All patients in which the virus has been newly diagnosed died between 1999 and 2019, and they all lived in southern Germany. However, the authors cannot rule out that it could be behind milder cases of encephalitis, especially in regions of central Europe where the infected host animal species occur in the wild. It was thought it might play a role in psychiatric disorders, such as depression or schizophrenia, but until the virus was reported in four cases in 2018, its links to unexplained encephalitis were rarely investigated.

Originally identified in sheep and horses in Europe, BoDV has since been found to occur in a wide range of warm-blooded animals including birds, cattle, cats, and primates and has been found in animals in Europe, Asia, Africa, and North America. The virus name is derived from the town of Borna in Saxony, Germany, which suffered an epidemic of the disease in horses in 1885.

Credit: Pixabay.

BoDV-1-infected bicolored white-toothed shrews can be found in Germany, Austria, Switzerland, and Liechtenstein, but how the disease virus jumps from shrews to humans is not yet understood. Symptoms in infected people start with a fever, headache, and confusion, and continue with signs of brain disease such as an unsteady gait, memory loss, seizures, and a progressive loss of consciousness. In the new cases, symptoms deteriorated rapidly following patients’ admission to hospital, leading to deep coma and death. All eight patients died within 16 to 57 days of admission.

“Our findings indicate that Borna disease virus infection has to be considered a severe and potentially lethal human disease transmitted from a wildlife reservoir. However, it’s not a newly-emerging disease, but one that appears to have occurred unnoticed in humans for at least decades, and may have caused other unexplained cases of encephalitis in regions where the virus is endemic in the host shrew populations,” says Professor Barbara Schmidt from Regensburg University Hospital, Germany.

Writing in an accompanying commentary, Tomoyuki Honda, Ph.D. from Osaka University, Japan, said the study “has several implications for the pathology and epidemiology of bornavirus infection. It is time to relaunch human bornavirus research based on a theoretical framework that integrates the knowledge from these confirmed human bornavirus cases.”

Scientists find new shrew species in Philippines — in a special “sky island”

The new shrew can teach us a lot about biodiversity, habitats, and even flood prevention.

An illustration of the newly identified Palawan moss shrew.

The Philippines is teeming with life — with over 200 species of mammals, 400 species of reptiles, and almost 700 species of birds, it’s definitely one of the planet’s biodiversity hotspots. Now, we can add one more creature to that very long list:  a shrew found around 5,000 feet (1,500 meters) above sea level.

Palawanosorex muscorum, commonly known as the Palawan moss shrew, was first spotted 2007 by the late Danilo “Danny” Balete, field survey leader and research associate at the Field Museum. Unlike other shrews, this critter’s tail is covered in dense fur rather than visible scales. Sporting a slender, pointed snout, a dark coat, and long claws, the Palawan moss shrew spends most of its time digging through moss and humus for its favorite snack: juicy earthworms.

Rainer Hutterer, the paper’s lead author, carried out a detailed analysis of all these traits and behavior, ultimately concluding that it was indeed a different species. Larry Heaney, Curator of Mammals at the Field Museum in Chicago, who also worked on the paper, said that the discovery of the species wasn’t surprising in the least — after all, its habitat is a biodiversity hotbed.

“In many ways, finding this species was exactly what we had expected,” Heaney explains.

But perhaps even more important than the animal itself, the finding could show biologists how the Philippines‘ many mammal species got there in the first place, and how they became so unique.

Mount Mantalingahan, a peak of 2085 m, in the Philippines. The summit ridge is two to three days distant on foot, and one and a half days on the downward return journey. Image credits: Alastair Robinson, July 2007.

For instance, Heaney says, the Palawan moss shrew’s home is a hotbed within a hotbed. Mt. Mantalingahan, where the shrew can be found, is home to three unique mammal species, including the shrew.

“There are entire countries that don’t have three unique mammal species — so for there to be three species on one mountain, on one island, in one country is really something,” Heaney emphasizes.

So how can this extreme biodiversity be explained? The key lies in something called “sky islands”. Far from being a sci-fi concept, a sky island is an isolated mountain habitat surrounded by radically different lowland environments. The isolation has significant implications for these natural habitats, creating hubs of biodiversity, which allow multiple species to thrive and coexist within a single geographic area.

However, because these rich habitats are so isolated, it also makes it more difficult for biologists to study them.

“There could be many new species on these high mountainous regions in the Philippines, but because they are so high, and hard to get to, knowledge of their existence is awfully limited,” Heaney says.

But the shrew’s home, Mt. Mantalingahan, also serves as a crucial watershed, regulating the flow of water in Palawan through natural processes. In the higher parts of the mountains, there’s a great amount of rainfall. The humus through which the shrew likes to dig through, searching for worms, acts as a sponge, preventing all the water from going off the mountain. Deforestation, which almost always has negative effects on biodiversity, can be even more devastating on these sky islands — not only on the creatures inhabiting the ecosystem but also on the lowland people, which depend on the rainfall water.

“That’s where most of the water comes from that people in the lowlands depend on,” Heaney warns. “In deforested areas, when a typhoon hits, it kills thousands of people and animals, and destroys buildings. And if water isn’t being released slowly from the mountains, you’ll have less of it in the dry season, causing drought. If you want to protect your watersheds, you’ve got to protect your habitats.”

Many developers have been asking to tear down some of Mount Mantalingahan’s forests for industrial development. But as Palawan, which hosts over half a million people, greatly relies on the flow of highland water, it’s in the best interest of everybody to keep the forests as intact as possible. So in this particular case, the smart economic bet is to not develop at all.

“Sometimes it’s presented that environmental concerns and economic development are at odds with each other. That’s false,” Heaney asserts. “Smart economic development means not creating situations that cause mass damage as a result.”

Beyond the economic advantages, researchers hope that the discovery of new species, such as this shrew, can spark excitement among the Filipino and international scientific communities, which in turn can help encourage research, conservation, and advocacy efforts — something which is much-needed in areas such as the Philippines.

“People in the world get excited about the cool things that live in their country,” Heaney says. “The fact that the Philippines is such a unique hotspot for mammalian diversity is something people should be aware of, something that people can take pride in.”


Shrews literally shrink their heads with the seasons

A mind-boggling new study showed that red-toothed shrews (Soricinae) shrink their skulls and brains by up to 20 percent during the freezing winter season. The shrews gradually regrow skull tissue with spring and reach peak head size during summer.


Credit: Pixabay.

Biologists have been aware that the heads of shrews seem to shrink seasonally for some time. Previous studies who followed and measured shrews at the population level found the height of the animals’ braincase declined by 20 percent during winter and increased by 15 percent during summer. There’s an even a name for the observation called “the Dehnel phenomenon”, after famed zoologist August Dehnel who first documented the peculiar cranial shrinkage in 1949.

This time, researchers at the Max Planck Institute for Ornithology in Germany measured shrew heads on an individual basis, rather than across populations. The animals were first captured using live traps from the summer of 2014 into the fall of 2015. Researchers then X-rayed the anesthetized shrews to measure their skulls and implanted a microchip under the skin for later identification and tracking.

The measurements of shrew heads taken over the course of the seasons confirmed the Dehnel phenomenon, authors write in a Rpaper published in Current Biology. Twelve individuals of the species Sorex araneus, for instance, were captured at all three stages showing the same pattern: the skull size peaked in summer, declined in winter, and started to recover in spring.

“We found that each shrew undergoes a dramatic decrease in braincase size from summer to winter,” said lead-author Javier Lazaro of Max Planck Institute for Ornithology in Germany. “Then, in spring, the braincase regrows, almost reaching the original size in the second summer.”

It’s not only the head that shrinks. Lazaro says the entire shrew body seems to undergrow transformations in size. During the winter, several major organs lose mass, the spine gets shorter, and brain mass decreases by 20 to 30 percent. It must feel stupidly cold for the shrew.

Scientists don’t know for sure why shrews learned this adaptation but they have some hunches. Because they have a fast metabolism, the body shrinkage could help the shrews better cope with harsh winters when food is scarce. Unlike other mammals, shrews don’t hibernate or migrate.

“Reducing head size–and thus brain size–might save energy disproportionally as the brain is energetically so expensive,” Lazaro says.

As to how this remarkable transformation takes place, evidence so far suggests the braincase drops in volume as tissue within cranial sutures is resorbed. Bone tissue later regenerates once spring approaches.

Scientists say understanding how the shrew does its magic trick could potentially one day lead to cures for skeletal diseases in humans.

Next, the researchers plan on investigating in greater detail the process that causes structural changes in the shrinking shrew brain. They’re also interested in learning how all of this affects cognitive abilities.

Photo: California Academy of Sciences

This sweet shrew looks like a mouse but is more related to elephants

Photo: California Academy of Sciences

Photo: California Academy of Sciences

A new mammalian species has been discovered among the ancient volcanic formation in Namibia that resembles a long-nosed mouse, but which as it turns out is more genetically related to elephants. Further analysis found that the tiny mouse-like creature is the smallest of a group of animals called elephant shrews.

Named Macroscelides micus, the creature sports red fur to help it blend in with the color of its rocky surroundings, measures 7.5 inches (19 cm) in length (tail included) and only weighs roughly an ounce (28 grams). It’s tiny ball of fury delight, made even more adorable by the fact it’s most closely related to an elephant according to genetic analysis. The only visible link between the two, however, is the shrew’s trunk-like nose.

The newfound elephant shrew, Macroscelides micus. Dumbacher et al / Journal of Mammology

The newfound elephant shrew, Macroscelides micus. Dumbacher et al / Journal of Mammology

It doesn’t end here, though. The elephant shrew is related to other animals as well, this time in behavior and physique. The newly discovered animal can be likened to an antelope because of its spindly legs relative to its body size, and because it hunkers down next to bushes to sleep rather than burrowing. Also, concerning its hunting patterns, the elephant shrew behaves like an anteater using its extended nose to sweep the ground in search of ants and other insects.

The creature was described in a paper published in the Journal of Mammalogy.