Читать книгу The Otters’ Tale - Simon Cooper - Страница 10

As far as the weather is concerned, otters don’t worry unduly about the seasons; they are perfectly adapted to anything the British climate might throw at them, unlike, say, their tiny, semi-aquatic, fellow river dwellers the water voles, which are easily wiped out by a spell of damp weather, floods or the sudden arrival of a predator. Being at the top of the food chain helps, but, more importantly than that, the otter frame is honed for survival. You might have thought that, for an animal constantly in and out of the water, blubber was the key to insulation, like, say, a seal, but otters carry just 3 per cent of their body weight in fat. In seals it is more like 25 per cent, which is close to that of the human body. So what is it that keeps otters warm and dry?

A clue lies in the luxuriant fur which the otter, when not swimming or sleeping, is frequently grooming. To start with, otters generally look close to black when wet, but actually, when dry, their fur is more of a brown colour and incredibly soft to the touch. Kuschta’s Californian sea otter cousins have the densest fur of any animal on the planet, at 140,000 hairs per square centimetre. On its own, that figure doesn’t mean much, but when you reckon that the arctic fox, one of the most durable survivors of polar winters where the temperature may drop to as low as -20°C (-4°F), has fur with a mere 20,000 density, then the British otter, even though it trails the sea breed at 80,000, has a pelt for life. If you are wondering about us, a density of 300 on the human scalp tells you everything about the importance of hats.

Kuschta’s fur, like that of a polar bear and other mammals which are constantly immersing, is dual-layered. The top layer consists of outer guard hairs, which are thick and long and form a partial barrier to keep the fur beneath dry. As she climbs out of the water, Kuschta’s pelt will look anything other than smooth and sleek, but rather spiky, the coat almost like that of a hedgehog. This is because the hairs combine in little arrows to draw and drain the water off the body. But it is the underneath, the under-fur, the really dense stuff, where the otter is so truly well adapted for life in a river. Regardless of any density quotient, the ultimate test of the under-fur is that in whatever direction you stroke or pull at the half-inch hairs, you will not see the skin below.

However, the fur alone is not enough to insulate the otter. It takes one other crucial component, namely air, which, once trapped between the hairs, keeps out the cold – a sort of mammalian double-glazing – hair, air and then more hair. Grooming is, of course, about drying out and keeping clean, but it is equally for puffing up the under-fur to let air back in. And it’s a lot of air. To track an otter swimming underwater, watch out for a tell-tale line of air bubbles rising to the surface – wherever the otter goes, the bubbles will follow. For otter hunters it was a tracking gift from heaven and something the otter cannot avoid, for the bubbles are not created by breathing but by the pressure of the water gradually squeezing the air from the pelt. And because of this there is a definite time limit as to how long an otter can spend in water. After about half an hour the air has gone and both layers of fur are completely sodden, the cold water pressing against the skin, sucking heat from the unprotected body. Again, otter hunters knew this. If they could keep the otter immersed for long enough, regardless of how many times it surfaced for air (they can hold their breath for up to four minutes but rarely do so for more than 30 seconds), hypothermia would set in, hastening the end. Conversely, in the heat of a summer day, lounging on her couch, Kuschta would be content to leave her damp pelt well alone, the slowly dissipating air allowing her to keep cool, her coat fluffing and lightening to a more roan brown the longer she lay.

To find her place within this singularly convoluted riverine society, Kuschta established a pattern whilst alone during the summer and autumn months, exploring and testing each new place she came across. Sniffing tell-tale marks, she was now old enough to make a swift decision whether to move on or stay. Moving on was always her first choice because it involved least risk of confrontation, whilst staying was more nuanced, but on one particular night her luck changed.

Kuschta sat for a while at the base of the ash tree at the end of the promontory where the river split; she was perplexed. Everything she’d ever learnt told her this junction pool was a classic boundary marker, a feature in the river landscape that all otters would recognise and mark accordingly. But she had been up and down, crisscrossing the entire isthmus to check for signs of other otters, and … nothing. So if her nose told her nothing, maybe her ears would reveal some other presence, for otters have acutely sensitive hearing. To look at their tiny ears you wouldn’t think so, but I’ve frequently learnt this to my cost – until they dismissed it as benign, the slightest click of a door lock from my mill in the dead of the night was enough to scare the otters away before I ever saw them. No wonder that for me and so many others they can be such elusive creatures.

Otter hearing breaks down into two categories: in air good, in water bad. Despite water being such a good conductor of soundwaves, otters are not adapted for underwater hearing like, say, a dolphin or some seals, and in fact the auricle – the furry, half-moon visible part of the ear outside of the head – has a reflex response, closing over the ear hole when the otter submerges. Beneath the surface, touch, smell and sight are more potent senses. In air it is an altogether different story because otters have a range of hearing that is far more sensitive than that of humans, taking in a spectrum of high-pitched sounds something akin to that of a dog. For a creature that lives by the night and which has vision limited to movement and blurry shadows, acute hearing makes perfect sense.

After a long while of waiting, Kuschta had heard nothing beyond the usual night sounds, so with no real way of telling which was best, she took the right-hand fork; it was smaller than the other side but the stream appealed to her, the overgrown banks seemingly untrodden by human or otter. From her low viewpoint she couldn’t see far, but the dense reeds, interspersed with stunted alders crowding in up to the river edge, gave her a comforting sense of protection. At its narrowest point the reeds had fallen across the stream, supporting each other at the middle, creating a cathedral-arch-like tunnel that stretched into the darkness.

The mass of vegetation barred any further progress along the bank, which suited her just fine. Otters are not ideally built for walking or running; watch them move anything faster than ambling pace and you’ll see their back end rise and fall in a sort of jerky, lolloping, uncomfortable way. You worry that with all the strength in their hindquarters the front end won’t stand the strain, or at the very least the otter will tumble into an involuntary front roll as the rear end overtakes the front. Otters are a bit of a mammal oddity; a creature that lives on land but is really best adapted to life in the water. They clearly know this – in all the years I’ve lived amongst otters they have never tried to outrun me for any distance. Actually, though I’m certainly not an Olympic athlete, they couldn’t anyway, as the top otter speed is little more than fast human walking pace. When in flight, the otter tactic is clear – head for water as fast as you can. It always amuses me because they go from sheer panic on land to total confidence in the water within the blink of an eye. Once immersed, rather than swimming away into the distance at speed, they’ll take a couple of strokes to where they feel safe, surfacing to gaze back at me as if to say ‘Fooled you!’ before disappearing off.

Unless in flight, an otter is not the type of animal that hurls itself into the water. The act of movement from land to water is one of the most fluid motions you will ever see in nature. It is a sublime rendering of evolution: that moment when a creature is so totally in harmony with the many elements it occupies that you can only marvel at the grace. To say an otter pours itself into the river is no exaggeration; it is almost as if the water parts to welcome the creature home. Slipping into the water creates no alarm. Draws no attention. For an animal that relies on the element of surprise to hunt, stealth is no bad thing.

It was with this sinuous action that Kuschta moved from land to water, content in her own mind that, for once, she was perhaps entering vacant territory. Otters may be elusive but they are big, leaving distinct trails in the landscape. They may be able to enter water like a spoon sliding into honey, but getting out is something else altogether. Steep banks, together with that long, heavy frame, leave their mark – a few ins and outs at the same spot creates a slide, a muddy runway in the grassy bank. Kuschta saw no such slide. Otters are great creatures of habit in the routes they follow. Kuschta made the simple evaluation – no slides, no otters.

Cruising upstream with flicks of her webbed paws, Kuschta is barely visible, leaving only a slight silvery wake through the tunnel of reeds. As otters swim, at least nine-tenths of the body is below the surface; only the top of the head protrudes, with the nostrils open, eyes wide and ears pricked, ever alert. Sometimes, when extra effort is required, the rump and tail will appear above the surface, giving the impression of a three-humped creature, but for the most part the strong legs and tail stay beneath the surface, giving propulsion enough. Though perfectly at home in the river, the otter is an alien and ominous presence to most other river dwellers. They may be silent and invisible to people, but Kuschta’s entry into the stream created enough disturbance to frighten the small trout that were using the cover of night to feed away from the preying presence of larger fish. Alarmed by her arrival, they fled for cover amongst the roots of the reeds. All this Kuschta sensed through her whiskers, the tiny vibrations at first close, then far. But she paid them no heed. She was after bigger prey. For now she needed to move on, so as her own vibrations faded the trout headed back out in her wake to continue their search for food, life returning to normal.

After a while the reeded, scrubby bank gave way to open meadows, the river now wider and shallower. Shorn of any bank cover, the moon shone down directly on the surface, lighting a bright path of water ahead. Other than Kuschta, nothing moved or stirred. She was in that nether time of night when the chill had settled and the bats and owls were back in their roosts. The grass had turned cold damp, enough to send the furred creatures to ground – rabbits and voles care little for getting wet when there is scant prospect of warmth; they would be waiting for dawn before reappearing. The isolation suited her just fine, so she swam on strongly against the steady current, putting distance between her and the stream junction. As the river meandered first this way, then that, she began to tire, getting a little cold herself. Easing up onto a tree root that dipped down into the water on the inside of a sharp bend, she took stock.

Otters are rarely idle. Kuschta surveyed the river whilst all the while grooming herself, both the effort and the effect gradually bringing the warmth back into her body. Perched on the root, dried and rested, she could afford to take her time – she had chosen the warmest spot on the river. Otters exploit the smallest wrinkles in nature; her perch was one such wrinkle. With certain rivers, at particular times of the year, the water is considerably warmer than the air, and where the two meet a blanket of warm air, a layer no more than a foot or so thick, hugs the surface. If you ever see a ‘smoking’ river, that’s the evidence, and by inserting herself beneath the mist, close to the water, Kuschta was exploiting nature’s very own greenhouse effect.

Everything about the bend in the river screamed fish; the tapering flow on the inside bank on which she sat had just enough slack water where a fish might rest. The faster middle would be empty, the effort/reward ratio too much for any fish to bother to hold station in. The far bank, with its undercuts, back eddies, tree roots and depth, was fish heaven – they could lie in there night and day, ready to dart out to any food that drifted their way. It was time for Kuschta to make a move. Slipping into the water, she let the current carry her downstream for a few yards, then simultaneously turned and dived, pushing herself hard and fast along the inside bend, as close to the gravel river bed as she could – the closer she stayed to the bottom, the fewer options the fish had to escape; they could go left, right or up, but not down. In the dark she could see very little. But no matter; her whiskers were doing all the seeing.

She couldn’t be sure, but maybe a fish had darted off into the distance. She let it go. Her hopes were really pinned on the far bank. By her estimation the fish would be facing upstream, looking out for food, so if she came at them head-on she’d have a crucial moment of advantage as they had to turn to flee. So surfacing well upstream, she coughed in that way that otters do, noisily sucked in air and dived. Her swimming, combined with the current, moved her fast. For a short moment the fish didn’t notice her coming, her movements masked by the midstream current. But then in total alarm they knew there was something dangerous amongst them. Kuschta’s whiskers were alive with information. She lunged as a trout slipped for cover under a tree root. Her teeth grazed another that bounced off her head. She accelerated after a third but it had too much of a head start. Undeterred, she surfaced, paddled for a moment to recover and then headed down deep, preparing to get amongst the roots this time.

It is something of an irony that any fish would be best advised to do nothing when hunted by an otter; by remaining still, the chances of detection in the dark, swirling water would be next to zero. But flight is the natural instinct of fish, so otters exploit this primordial reaction to danger. The fact was, Kuschta had no exact idea where the fish lay, she just knew that they were probably hiding in the cavity beneath the tree roots, and if she could spook them their instinct for flight would lead her to them.

Rising from below and slipping between the trailing roots that hung down in the water, Kuschta’s bulk filled the confined space. Any speed advantage the fish might have had over her was gone as she drove them down a watery cul-de-sac. Was it two, three or four fish? She couldn’t really tell, such was the confusion as they tried to push past her to the safety of open water. However many it was, it didn’t really matter – she needed just one, the currents of vibration honing her in on a fish trapped between her and the bank. The soft belly of the fish gave a little as she made contact with it with her mouth before she drove her long, curved canine teeth into the flesh. The now-wounded trout flexed head and tail in unison to escape the pain and capture. Reversing out, Kuschta kept her jaws clamped tight, the backwardly curved teeth maintaining a certain grip on the struggling fish. Breaking the surface, Kuschta’s nostrils flared open to breathe in air, whilst the trout splashed and crashed about her head, in a flailing death throe now exposed to the same air. Swimming back across the river, Kuschta headed for the root perch, scrabbling up and out, sending a spray of water all around as she delivered the coup de grace, violently shaking the fish to snap its spine.

Kuschta didn’t bother to groom or preen; she ate as if her life depended on it. By the time the first fingers of the cold winter dawn showed across the meadows she was done, the leftovers just a ragged tail. It was time to hide. Her eye was drawn to a mess of dried reeds and twigs that had been gathered up then left behind by a recent flood, piled up against the base of the tree. Pawing at the pile, she exposed a gap in the web of roots at the base of the tree. Squeezing through, she found a small cavern beyond, the sides and roof made up of old, gnarled brown alder roots, most of their growing done. The floor was softer, still alive, a bed of little pink nodules ready to sprout in the spring. Dragging some of the leaf litter inside, she circled around as best she could in the tiny space, fashioning a comfortable mattress which she nestled into. Sleep was not long coming, but before Kuschta finally drifted off she sensed she might finally have found a place to call home.