Sure, you learn that proper. Within the forests of Chile’s Valdivian Coastal Reserve, there’s a small mammal recognized, in English, because the “long-nosed Chilean shrew opossum.” In Spanish, it’s comadrejita trompuda, and to scientists, it’s Rhyncholestes raphanarus.
In all languages, this fascinating relict marsupial is the final of its variety—the one recognized dwelling member of the Rhyncholestes genus of shrew opossum remaining on Earth. Scientists consider it has lived, largely unchanged, within the temperate forests of Chile and Argentina since a minimum of the Oligocene (between 36 and 23 million years in the past).
Nonetheless, regardless of its longevity and all of the developments in science and data, notes researcher Eduardo Silva of the Universidad Austral de Chile, “the long-nosed Chilean shrew opossum [remains] one in all Chile’s least-known mammals.”
The Least Identified of the Little Identified
The primary long-nosed Chilean shew opossum was described by science in 1924. Zoologist Wilfred Osgood was exploring the West Coast of South America and noticed a small “shrew-like” animal within the temperate rainforest on Chile’s Chiloé island. Whereas he by no means documented long-nosed shrew opossums on the mainland, he predicted the species can be present in comparable temperate rainforests inside Chile (and presumably Argentina).
He was proper.
There are two recognized populations of long-nosed Chilean shrew opossum. One on the island and one within the rainforest of the mainland. The present consensus is that hundreds of years in the past, half of what’s now Chiloé island was coated in glaciers—apart from an space of rainforest that remained unglaciated and related to the continental land mass.
In geologic time, the 12,000 years or so because the finish of the final Ice Age is lower than a blink. The 2 populations of long-nosed Chilean shrew opossums don’t seem to have had sufficient time to develop the variations that may separate them into subspecies of Rhyncholestes. And although some scientists have steered they need to be divided, probably the most complete morphological research of long-nosed Chilean shrew opossum I might discover (revealed in 2020) helps the single-species designation.
A (Very) Transient Evolutionary Historical past of South America’s Shrew Opossums
Which brings us to a fast dip into Linnaean taxonomy. There are seven species of South American shrew opossum, together with the Chilean long-nosed. All seven are a part of an historic however nonetheless surviving Order of marsupials known as Paucituberculata (which, like a variety of Linnaean taxonomy, appears like a spell from Harry Potter.)
The earliest fossils of the Order Paucituberculata are recorded solely from Antarctica and South America and date from the Late Cretaceous (between 100.5 million to 66 million years in the past). In the end, Paucituberculata break up into six completely different Households. 5 went extinct. One survived.
Caenolestidae, the household that accommodates the seven remaining South American opossum species, was that fortunate evolutionary winner. As famous above, relying on which supply you seek the advice of and when, the overall consensus is that there are 5 species within the genus Caenolestes, one within the genus Lestoros and one in Rhynochlestes.
Spoiler Alert: Shrew Opossums are Not Shrews
Regardless of its shrewish title and what might be thought of a considerably rat-like look, the long-nosed shrew opossum is neither a “true shrew” nor a rodent. It’s on a totally completely different department of the mammal household tree. (And pound for pound presumably the weirdest department.)
Shrew opossums are marsupials—very, very distantly associated to the kangaroos and wallabies of Australia, and the Virginia opossums of North America. The primary factor to know right here is that in contrast to placental mammals (suppose: true shrews, different shrews, elephants, canines, rats and, properly, individuals) whose younger develop throughout the mom’s physique, marsupial mammals carry their embryonic younger exterior their our bodies.
However in contrast to these kangaroos and wallabies, not one of the seven surviving species of South American shrew opossum, together with the long-nosed Chilean, have an apparent pouch (known as a marsupium). On this, shrew opossums are extra akin to the equally pouchless Virginia opossum.
Like embryonic Virginia opossums, embryonic shrew opossums connect to their mom’s teats (mammae). The teats then swell of their mouths to assist them maintain on till they’re massive sufficient to forage on their very own, or to be left alone for a short while in a burrow or a nest.
Not less than, that’s what scientists suppose. Not all that a lot is understood concerning the behavioral ecology of shrew opossums basically, and that goes triple for long-nosed Chilean shrew opossums.
What’s in a Identify? A Lot of Variations from Different Shrew Opossums
Would possibly as properly begin with the nostril (rostrum). It’s the longest nostril of all shrew opossums and the apparent supply of the animal’s title (a minimum of in English). The even have the smallest ears. The variations go on from there. And regardless of a prolonged literature search, I couldn’t discover any constant measurements of precisely how lengthy the long-nosed Chilean shrew opossum’s nostril is. Most sources say one thing alongside the strains of “the longest rostrum of all South American shrew opossums.” So we’re going with that.
The measurements under are from the 2020 morphological research of long-nosed Chilean shrew opossums. However even the authors of that paper famous they solely had 77 specimens (or components of specimens) housed in museums world wide to work with. So there are nonetheless many gaps in data, which is among the causes there’s a lot “seems to,” “suggests” and “might” language on this story.
That mentioned, right here’s the rundown: The long-nosed shrew opossum is generally brown or ‘brownish-gray.” Males look like barely bigger and heavier than females, however each sexes are nonetheless small and light-weight: weighing, on common, round 1.5 to 1 ounce (45g and 38g) for women and men, respectively.
There are the identical slight variations in common size. Males are available round 7.5 inches and females round 7 (together with the tail). The long-nosed shrew opossum’s tail is shorter and stubbier than different shrew opossum tails suggesting that it doesn’t climb timber and spends most of its time on the bottom in burrows or nests. And it could retailer fats in its tail.
In truth, that tail—that may broaden from 4-5mm in diameter throughout summer time to 9-11mm in early winter—is the place the long-nosed Chilean shrew opossum will get one in all its names: R. raphanarus. Raphanarus means “radish tail” and in line with one supply, is a reference to the seasonal accumulation of fats within the tail and the idea that it seems to be like, properly, a radish.
Due to that adaptation, there’s hypothesis that they might expertise torpor through the Austral winter. There isn’t sufficient information to say for sure that long-nosed Chilean shrew opossums hibernate (or enter prolonged torpor). One other data hole. There’s doubt that they enter torpor as a result of they’ve been noticed on snow pack, they’re energetic 12 months spherical, and possibly most telling, reproductively energetic males have been captured in all seasons.
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Alone amongst different shrew opossum species, feminine long-nosed shrew opossums have seven nipples as an alternative of 4. However nobody has captured or documented a feminine long-nosed Chilean shrew opossum with younger so nobody actually is aware of the typical variety of a brood or litter. Or how lengthy embryonic long-nosed shrew opossums take to develop sufficiently big to outlive alone for brief durations in a nest or burrow. Not like the reproductively energetic males as talked about above, reproductively energetic and lactating females with out hooked up younger have been captured solely in summer time.
Each sexes are seen and captured most frequently at evening, suggesting a nocturnal life cycle. They eat principally bugs, fungi and seeds.
Scientists additionally discovered that the long-nosed Chilean shrew opossum has solely 22 caudal vertebrae as an alternative of 27 like different shrew opossums. (Caudal vertebrae are the bones of the tail.) Lengthy-nosed shrew opossums even have the “most developed and most conspicuous” orbitosphenoid of all shrew opossums (a bone that helps give the cranium rigidity and in addition helps the olfactory part of the mind.)
In truth, authors of the 2020 research additionally speculated that there are such a lot of extra variations within the enamel, jaw and bony constructions of the long-nosed Chilean shrew opossum cranium that it would symbolize a unique evolutionary path than the opposite six shrew opossum species. Which might undoubtedly be a really attention-grabbing discovering. For now, there aren’t sufficient long-nosed Chilean shrew opossum specimens or items of specimens for researchers to do greater than speculate.
TNC + Chilean Lengthy-Nosed Shrew Opossums
One of many extra apparent causes Chilean long-nosed shrew opossums are so little studied is as a result of, properly, the locations they stay could be tough to get to. And area work to watch species in distant areas is time-consuming, inherently time-limited, typically harmful, and just about at all times costly. Within the practically 90 years between the primary description of a long-nosed Chilean shrew opossum in 1924 and about 2011, the species was solely documented in 21 completely different websites, most throughout the Valdivian rainforests of Chile and a small neighboring a part of Argentina.
They appear to want undisturbed temperate rainforests, however within the Eighties and 90s, hundreds of hectares of forests have been logged, burned and a few of the land reused for eucalyptus plantations.
Partly, it was these burned and logged forests and the chance for conservation and restoration that introduced TNC to this a part of Chile. In 2003, TNC acquired round 60,000 hectares in a public public sale that included 3,500 hectares of eucalyptus plantations and created the Valdivian Coastal Reserve. Then, it promoted the creation of the Alerce Costero Nationwide Park by donating round 9,500 hectares to Chile’s Nationwide Forest Company (CONAF) (in Spanish) utilizing a mannequin that mixes private and non-private conservation efforts and group involvement.
Digicam Traps for Science
These private and non-private conservation efforts embody a monitoring framework that makes use of digicam traps. One of many many benefits rugged, long-lasting distant cameras is that they are often left in place for lengthy durations of time, like say within the temperate rainforests of the Valdivian Coastal Reserve. They usually can see at the hours of darkness.
On this case, in line with a paper revealed in 2023, utilizing information collected from the digicam traps of a monitoring program within the Reserve and Alerce Costero Nationwide Park, in addition to information obtained via different tasks, researchers and park rangers detected the presence of long-nosed Chilean shrew opossums on 31 events, throughout 17 websites: 15 within the Valdivian Coastal Reserve and a couple of within the adjoining Alerce Costero Nationwide Park.
The long-nosed Chilean shrew opossum was detected throughout all 4 seasons in areas of the evergreen and larch forests and, often, in eucalyptus plantations. For Danilo González, TNC’s park ranger coordinator within the Valdivian Coastal Reserve and a co-author on the latest paper, “it’s a pleasure to search out the species in numerous environments, in a higher vary of habitats.”
These findings symbolize a major enhance within the variety of websites with confirmed sightings of the species—practically equaling the earlier file of 21 websites registered in all these years between 1924 and 2011.
Scientists word that shortage of knowledge (once more) doesn’t permit them to discuss long-nosed shrew opossum inhabitants numbers. They do word that the species has a broader presence within the space than they’d beforehand recognized. Regardless of the presence of digicam traps, the long-nosed Chilean shrew opossusm has not been documented north of the Valdivia River.
“You possibly can see the burned larch timber within the increased areas, and in different spots, you possibly can see the substitute course of. Twenty-five years in the past, the realm was the reason for the Chilean forest tragedy, and at this time, it is among the major examples of conservation in Chile, a complete change of trajectory,” Silva factors out.
And excellent news for long-nosed Chilean shrew opossums, the researchers who research them, and other people like me, who’re simply completely satisfied to know an animal that has survived for millennia remains to be there—dwelling its life within the rainforests of the Valdivian Coast Reserve. And somewhere else we might by no means learn about.
