Treasures Beneath the Snow

Every spring, young green buds push through the white fluff. Every summer, life flourishes. Every fall, the green dies back and animals take cover. Each winter, the treasures of last season are locked away. Treasures beneath the snow.

It's a familiar story, but not one told so often on a younger Earth. Now, around each great ice cap and reaching down nearly to the equator, the majority of Earth's unfrozen land is subject to the yearly cycle between living summer and dead, icy winter. The two hemispheres alternate colors twice a year; one brown and white with the other tinged green, and then the reverse, and back again. With life on pause for a significant portion of the year worldwide, with energy tucked away in tubers and many creatures curled up in hovels or on vacation elsewhere, an opportunity arises for many a being able to use the resources sitting dormant.

To dig beneath the snow to find moss, lichens, tubers, or fungi is a reasonable tactic, done by reindeer, lemmings, and plenty others. Nearly all extinct, as it happens. To infiltrate the subnivium, or the relatively warm interface between the ground and the insulating snow, to prey upon the insects, amphibians, small mammals, and other little creatures lethargically lounging or methodologically moving, is an approach claimed by a larger number of survivors. In any case, both tactics appeared and reappeared many times in the intervening years, creating yet another battleground of organisms capitalizing on the same resources.

With competition comes the strive for efficiency. Digging in snow may be easier than in temperate soil, but the pickings are paltry. Putting in all the effort of burrowing through frigid fluff to get nothing but dead plants and an occasional small animal presents a shoddy deal, made worse by the dangers of the most life-stealing time of year. But there are better ways to get food out of the snow without trudging through too much of it, ways that would be harder to find on old Earth because of the relatively limited area, and timeframe, that the environment occurred. Now, that white line has expanded into nearly a whole hemisphere at a time.

Take this enterprising young species, a masked badger. Descended from Asian badgers from the central Asian highlands, a colder world brought some populations of them to search elsewhere for food as their species pulled through, enjoyed a brief moment of peace, then competed fiercely among their own. The ancestors of the masked badger found refuge in the permanent icy line separating India and Arabia, a line that stretches all the way to the Indian Ocean during the winter, and is thus difficult for other animals to traverse.

Masked badgers sport a luxuriously thick, fluffy coat, mostly white, and are smaller than their ancestors despite their chilly habitat. All year they live in the snow, moving north and south with the seasons. They dig burrows that stretch from the surface to down toward the ground, and sometimes into it, but they rarely inhabit the same burrow for long. Instead, they are constantly on the move. A masked badger will leave its burrow, walk along the surface a short distance, then create a new one, digging nearly straight down to the ground below. Once it reaches the ground, it now digs parallel to it, searching for anything: Fallen seeds, dormant plants, earthworms, small animals, tubers. The morsels are meager, but the digging is easy, hence their relatively small paws made for tossing aside snow and ice instead of scraping away at earth. Once a small area has been scanned, the badger will pop up and walk along the surface again to start the cycle anew. This way, a masked badger can cover ground rapidly, especially for a burrowing animal, and they thus have a well-mixed population.

An occasional windfall changes things. The elements often claim lives of the various species of ungulate that weather them, usually the young, old, or sick; a misfortune that a masked badger will excitedly locate once the scent reaches its sensitive nose. Upon finding a carcass, no time is wasted in digging a tomb for it, dragging it below, and covering it in snow as if nothing was there. Locked away, the carcass can provide many a hearty meal to the animal, a luxury compared to its normal lean diet. Burying the body serves to store it as well as to hide it from competitors. If other masked badgers arrive at the scene, they may tolerate each other and work together to bury it as quickly as possible, saving the quarreling for beneath the snow. A smaller find, however, will not cause a badger to give up its normal solitary nature, so it will fight viciously to defend it.

Unusually, masked badgers give birth not in early spring, but in late fall; a risky tactic for sure, but as their range is about to expand in the winter, the mother can more easily acquire food with less fear of meeting predators or competitors on the way.

Repeatedly searching beneath the snow is one effort-saving tactic, but staying above the surface to search for food is another. Prepared for this by coincidence only are one of the great winners of the new world, shrews. These already common, mostly carnivorous little mammals generate so much heat from their constant movements that they hardly need to expend any extra to keep warm, even in winter. Consequentially, their caloric intake is massive, often requiring multiple times their weight in food every day to survive, forcing them to constantly dash, dig, and scramble for their meals mostly of insects and small vertebrates. In the winter, there is still plenty of these prey items to find sheltering beneath the snow, but the energy to search and uncover them is a tough ask that some shrews have found a way around.

Enter this peculiar shrew, the pear shrew, so-named for its appearance from above: fat with a protruding little head. It has not just fat, though, but thick fur, shielding the little body from the bitter weather as much as possible. In contrast, their whiskers stick out as much as possible, the longest of which can be nearly as long as the entire body! Connecting these two contrasting features is a snuffling little head on a relatively long neck.

They can be seen dashing along the snow on fleet feet, though not too easily, as they are completely white. At times, they stop for just a moment, giant whiskers spread widely. Seemingly randomly, their whiskers will narrow, their pace will slow, and they will shake their heads slowly back and forth, as if scanning. They will hold still, their whiskers now splaying and narrowing rapidly, but the rest of them held as frozen as their surroundings. Suddenly, the animal will dive beneath the fluff, scrambling and burrowing with haste, kicking up little puffs of snow as it disappears, often for a while. What this animal has done is hidden from those with inferior senses.

The searching behavior with such long whiskers gently touching the ground is an attempt to feel what is moving below. Anything that moves — a spider sluggishly adjusting itself, maybe, or another small mammal moving about — will emit tiny vibrations. Pear shrews are specialized in detecting these vibrations, with a wide swath to pick up as many streams of data as possible. To save guesswork, a slowed or stopped shrew can pinpoint the source of vibrations with great accuracy, and when the time comes to catch the prey, the whiskers fold back against the body safely out of the way. Unfortunately for the shrew, however, snow is very good at absorbing vibrations, so a layer of ice-free snow that is over 12 or so centimeters deep will stage a difficult hunt. But they find use in their skills even here, as they can straighten their stiff whiskers, swing their necks to one side, and plunge their tips into the snow, penetrating closer to the ground and thus closer to the source of vibrations.

Pear shrews are entirely carnivorous, turning dozens of small animals into piles of hair, bones, and exoskeleton in a day. However, their fat little bodies would provide a scrumptious meal for so many animals more, and as luck would have it, they are quite vulnerable standing on open ground. For this reason and because their vision is poor, they scare easily, retreating into the snow with haste.

Snowcover of any permanent or even seasonal sort was previously unknown for some regions of the world. Take southern Africa as an example, once hot and arid, but now sporting a little glacial cap of its own surrounded by chilly biomes. Here, scant few of the local animals adapted readily to the new cold, and imports from abroad are uncommon with biomes of similar temperature so far away. Inevitably, strangeness and innovation came forth.

Egret-herons are one such example. By summer, they are typical herons, leering over shallow water for their quarry of fish and frogs. By winter, they migrate north, but not in search of thinly frozen lakes. Instead, they change. Purplish-gray feathers fall off, replaced with brilliant white, thick plumage, and their little head crests fall to the ground. They become egrets. Egrets, as it happens, are what species of white herons are called, as there is no biological difference. Uniquely, however, egret-herons may be called either depending on the time of year.

With late fall coating the familiar ponds in an icy glaze, the herons-becoming-egrets switch tactics as well. Instead of shuffling through water, they shuffle through snow. Their bodies and minds may be water-adapted, but probing the white expanse bears surprising similarities to probing the glossy one. After sighting a suitable hunting ground from the air, an erget-heron will alight gently upon the ground upon their weight-dispersing large feet and simply wait. Instead of a fish, they wish for a little burrowing mammal, likely a rabbit relative or a shrew — though never a pear shrew, as they do not inhabit southern Africa. When the little fellow sticks its head out for even a second, the heron-egret launches its head like a spear toward its target. Even if it misses, the heron-egret does not capitulate. It stomps its feet into the snow and beats its wings, kicking up snow in a hastened fury to hopefully reveal the inhabitant inside. Their keen vision, previously used for looking through murky water, can now spot the prey item through the thick flurry, and instead of attacking the prey where it sees it, the egret-heron predicts its future position and attacks there, even if such a future position is beneath the snow where the heron cannot see. This is not unlike targeting a fish, for light refraction also requires the heron to calculate and attack a position away from the fish's apparent image.

The egret-heron makes quite a living this way in the winter months, but not everything is so dandy. Their long legs, previously useful for fishing, release precious heat as the winter air bites, and there is only so much they can recover by sitting crouched up while at rest. Granted, they have some adaptations to keep warm: The featherless skin from their knees down to their ankles will grow insulating white feathers during the winter, only to go bare again in the summer, a feat of a sort few other animals can claim. Still, egret-herons will continue to move north as the temperature drops, spending the winter wherever the temperature meets their needs best. As spring rolls in, they will wander back to their breeding grounds, don their summer clothes, and raise their chicks on fish and frogs just as their ancestors did for so long.