FAuna

Pitch black vs patterned - how dark colouration gives advantages when hunting: adder and asps viper

Adder (Vipera berus) and asp (Vipera aspis) are the only poisonous snakes in Switzerland but they are found all over southwestern Europe. With their venom, they catch their prey: mainly mice, small birds, frogs and lizards. Like all reptiles, they are cold-blooded animals and cannot regulate their body temperature by themselves. They depend on the sun for warmth.

The adder mostly inhabits areas at altitudes up to 2700 meters in the Central and Eastern Alps. It is found mainly in the Swiss National Park, where it inhabits moist meadows, sunny forest edges and boulder fields. Asp viper lives also in the lowlands and prefers sunny and dry areas.

In addition to the usual brown and black patterned individuals, adder and asp viper can also be pitch black. This black colouration not only serves as camouflage for the cold-blooded vipers but also gives them another advantage: dark-coloured vipers can heat up faster, which improves their ability to hunt and escape. This is very important since they tend to live in cooler, higher-elevation areas. In warmer locations, these black individuals are more poorly camouflaged and thus are much more likely to be attacked by their enemies. These include martens, polecats, badgers, hedgehogs, ravens, and buzzards. Thus, the dark colouration is only worthwhile where the advantage of heat utilization is higher than the cost of being caught by their prey.

Flight artist of the peaks: the alpine chough

The bird most likely to be seen in the Swiss mountains is the alpine chough (Pyrrhocorax graculus), an agile flight artist easily spotted while hiking. A true high mountain specialist above the tree line between 1500 to 3000 meters all across the Alps, the alpine chough can be easily recognized by its black plumage, yellow bill, and orange-red legs. If the mountain chough moves to lower elevations, this may indicate bad weather is approaching.

Like many corvids, Alpine choughs live monogamously. They build their nests in rocky niches and lay four to five eggs, which are incubated for three weeks. Already one month after hatching, the nestlings go to flight school. Without flying, they cannot easily move from place to place in the high mountains.

Very gregarious, and even more so in autumn and winter, Alpine choughs gather to form large flocks sometimes exceeding 1000 individuals. This bird species specialises in spectacular flights over the cliffs to the rocky crests, with spiral climbs, known as "carousels", followed by sometimes vertiginous dives. With loose deep wing beats, the Alpine chough fans its tail, folds its wings, and soars in the updraughts at cliff faces.

As adaptive as they are, alpine choughs have adapted very well to humans i.e. tourists. In the vicinity of mountain restaurants, the birds approach tourists, who treat them to cakes or fries. However, the actual food alpine choughs eat includes insects, spiders, earthworms, berries, and other plant parts.

Alpine adaptation: how Ibex use their hoof to conquer mountains

The Alpine ibex (Capra ibex) is a species of wild goat found in most of central Europe including Alpine Switzerland. Once hunted almost to extinction for the medicinal properties attributed to its flesh and horns, nowadays around 300 ibex live in the Swiss National Park.

Ibex prefer staying on mountainsides above the tree line and only rarely descend into the forests. The animal’s ingenious foot anatomy allows them to be more agile than most other animals living in this environment and - very importantly - it allows for a fast escape from predators like eagles, bears, and wolves.

Even though the Ibex’s toes consist of the hard keratin also found on the hoof of a horse or deer, unlike horses, Ibex have hooves consisting of two split toes. The parabolic shape of the hoof wall adds strength, while a cushy sole with a rough surface provides extra friction on sloped surfaces and smooth rock and ice; the sole can also deform inwards to absorb irregularities in the terrain meaning it has a skid-proofing effect (Noe 2011).

To better understand how the hoof of mountain goats works, you can try it out yourself:

“Make a wide V with your index and middle fingers and try pressing down against something with their tips. Since walking on an artiodactyl hoof is anatomically similar to walking on the tips of two fingers, the mountain goat feels the muscles and tendons working against each other somewhat the way you do. It adjusts the tensions accordingly in order to fine-tune its grip on uneven surfaces. Now you will find that the more weight you put on your fingertips, the more they want to diverge sideways. In like fashion, the mountain goat’s toes divide the downward force of the weight on a hoof. When your fingers, or the toes of the hoof, are placed on an inclined surface, part of the weight continues to be directed sideways—a horizontal vector of force as distinct from the vertical vector. There is thus less net force being exerted in a single downward line; hence there is less likelihood of overcoming the force of friction along that line and beginning to slide. What is [happening] here is a fanning out of forces. If all the downward force could be converted into sideways forces, it would in effect be canceled out. The third and final dimension is simpler to explain. Solid rock, talus, dirt or snow can become wedged in the crotch of the ‘V’ and act as an additional brake” (Chadwick 1983: 51).

Living in the heights: the mystery of the Alpine long-eared bat

The Alpine long-eared bat also called mountain long-eared bat (Plecotus macrobullaris) is the only alpine bat in the world. It has been spotted all the way from Andorra, France and Spain (in the Pyrenees) to the Alps in Switzerland, France, Slovenia, and the Dinaric Alps. It  has also been found much closer to sea level in places like the Balkans and Greece. So how can an animal that normally only lives above 1,500 meters in the Alps or Pyrenees also manage to live near sea level in Croatia?

A research group from the University of the Basque Country conducted a study to answer this question and found that the habitat of these bats is not defined by a specific climate only found in high mountain areas, but by a rugged environment with enough rocks, crevices, and ledges to hide under and enough open spaces to forage insects. In short: these bats live in high mountains including the Swiss Alps for topographical reasons; they depend on the characteristics of the landscape to survive.

In Croatia, these conditions can be found at lower altitudes, and in Switzerland, they can be found in the Alps. In this latter case, this means that the Alpine long-eared bats have to withstand the cold alpine climate but since many other species cannot bear these conditions, this bat species can avoid competition. The distribution of Alpine long-eared bats is mainly shaped by topographic factors that provide rock-abundant and open-space habitats rather than climatic factors, i.e. the species is not a cold-adapted, but rather a cold-tolerant eurithermic organism (euritherm = can function at a wide range of ambient temperatures).

The Alpine long-eared bats have large home ranges (larger than 10 km^2) and prefer ecotones (steep transition between ecosystems) and rural areas (villages) and avoid woods. Breeding females select more strongly for ecotones.
Why do Alpine long-eared bats use such large home ranges? This pattern can be explained by the Resource Dispersion Hypothesis (RDH), i.e. the variation in home range size of the bats will not only be a function of insect prey availability in patches (in this case ecotones and rural areas) but also of spatial dispersion of the patches of preferred habitat types.

Beauty king among the beetles: the alpine longhorn beetle

Alpine longhorn beetles (Rosalia alpina) are distributed from Cantabrian Mountains east to Caucasus. Unfortunately their numbers across Europe have dramatically decreased in the past years, and they are now a protected species in Germany, Hungary, Italy, Poland and Slovenia.

They spend most of their lives - 2 to 4 years - in the larval stage hidden in beech deadwood. Because of this, they are “saproxylic” invertebrates i.e. they depend on dead or decaying wood.
When they pupate and finally hatch as beautiful beetles with their characteristic blue-black pattern and long antennae, they only have 3 to 4 more weeks to live during which they feed on tree sap. Males emerge almost a week before females and remain on the tree’s dry, sun-exposed trunk defending their territory against other male competitors.

Like other longhorn beetles, on warm days the beetles fly around their breeding trees or search for new breeding trees or logs. The most important factors influencing the choice of trunk to lay eggs are wood volume, sun-exposure and decay stage. The larvae feed in the sapwood and avoid the nutrient-poor heartwood. Unfortunately, sometimes the females also lay them in firewood occasionally which means the larvae are burned. Therefore it is all-important to leave deadwood available for the larvae and the developed beetles.

The high variability of the dorsal pattern in the beetles can be used for individual identification. The antennae show a clear sexual dimorphism: they are a little longer than the body in females, and up to twice the body length in males.

The alpine longhorn beetle is endangered or critically endangered in most European countries but the population is doing better in Austria, Switzerland and Slovakia, where the distribution is less fragmented. The major explanation for its decline is the transformation of beech forests into conifer plantations.

Amphibians in the Alps: the Alpine salamander

The Alpine salamander (Salamandra atra) is not only unique because of its adaptation to cold Alpine habitats but it also stands out for its unusual reproductive style.

These shiny black animals prefer karst areas and mountain ravines at elevations between 800 and 2500 meters above sea level that are shady and moist. They are distributed from the France–Switzerland border all the way through Austria to the Dinaric Alps.

Because they are amphibians, they don’t create their own body heat, so it is quite fascinating that they manage to live at such high altitudes up to 2500 meters where it’s cold. To cope with the coldest temperatures they hibernate from October to April. During the warmer months, they hunt at night for insects, spiders, larvae, woodlice, snails and worms, and during the day, they hide among rocks and deadwood.

Unlike other salamanders that typically lay eggs or larvae in water, female Alpine salamanders give birth to one to two 3 - 5 cm-long fully-developed juveniles. The gestation period varies depending on the altitude: At altitudes of 650 - 1000 meters above sea level, a pregnancy lasts two years; at altitudes of 1400 - 1700 meters it lasts around three years.

Although the Alpine salamander is not an endangered species, it is a protected species in Switzerland, Germany and Austria and it is important to preserve its preferred habitat i.e. rocky and not-too-dry landscapes with moderate vegetation.

Organic waste recyclers in the Alps: the bearded vulture

With an impressive 3m wingspan, the bearded vulture (Gypaetus barbatus) is probably the most famous bird in the National Park that every hiker, photographer and tourist wishes to get a glimpse of. With its wide range, the bearded vulture is not only limited to Switzerland but it occurs all over the European (mainly in the Alps and in the Pyrenees), the Arabian Peninsula, the Caucasus region and all the way to mountains regions in Afghanistan, the Himalayas, northern India, and western and central China. It can even be found on most of the African continent. It became extinct in the 19th century in the Alps but was successfully reintroduced between 1991 and 2007 when 26 young captive-bred bearded vultures were released in the park’s Stabelchod valley.

The former German name for this bird ‘Lämmergeier’ means lamb-vulture which stems from a mistaken belief that it attacks lambs. But we have learned that rather than being scared of them, we should admire the very important role bearded vultures play as waste recyclers.

They feed on carrion and bones which helps prevent the potential spread of diseases that flourish in rotting carcasses. In order to access the fat and protein inside the bones i.e. in the bone marrow, bearded vultures drop the bones from a height onto stone slabs so the bones splinter. The stomach of Bearded vultures contains a high acid content estimated to be of pH about 1 which makes it possible for them to digest large bones in about 24 hours. This waste recycling strategy has allowed the bearded vulture to occupy a quite uncontested ecological niche and avoid competition.

With humans producing so much waste, is there anything we can learn from bearded vultures? Could we somehow create a similar acid in order to dissolve and dispose of man-made waste, and if this was to work, what gases would be produced that we could use in biodigesters?
Perhaps these are questions to ponder about…

Swiss lakes: A hotspot for whitefish: the Brienzlig

Most of the fish species found in Swiss lakes are endemic to those lakes i.e. found exclusively in their respective lakes. Whitefish species for instance are found in open water and in very deep habitats of nutrient-poor waters like the Lakes Brienz and Thun.

One specific whitefish species is the Brienzlig (Coregonus albellus) found in the lakes Brienz and Thun that are connected by the short river Bödeli Aare at Interlaken. It feeds predominantly on zooplankton and has a slow growth rate. In Lake Thun it occupies the moderately shallow to the deepest benthic waters (30-217m) and the moderately shallow to moderately deep pelagic waters (10-70m). In Lake Brienz it can be found in the very shallow (few meters) to the deepest waters (260m) of the benthic habitat and the very shallow to the deeper waters of the pelagic habitat (few meters to 60m). (Note that this data for both lakes only covers a short period of summer, so it is not clear how the species are distributed through the rest of the year.)

How can these fish inhabit both shallow and deep waters?
After the last ice age, two or more whitefish species developed in all the major prealpine lakes. The hybridisation of two ancient whitefish lineages highly increased the genetic diversity of their descendants, allowing them to adapt to the wide variety of habitats in the deep lakes offering different types of food, spawning sites and spawning seasons.

“C. albellus has a long spawning season with two peaks. The main spawning peak is in late summer/early autumn from August to October (locally known as "Sommer-Brienzlig") and the second peak is in early to late winter from December to March (locally known as "Winter-Brienzlig") Spawning depth varies with spawning season and can range from approx. 30m to max. lake depth at 217m in Lake Thun and approx. 50m to max. lake depth at 261m in Lake Brienz.”

Due to pollution and eutrophication in Swiss lakes after the mid-20th century, a third of all whitefish species became extinct or merged genetically with other whitefish species.

(Image credits: Alchetron)

Excellent recycler and caring parents: Burying beetles

The 12-24mm long burying beetles (Necrophorus vespillo) can be found in a wide variety of habitats (especially meadows, parks, forest paths, clearings) across Europe and Asia, extending from Western Europe to Mongolia.

They are not only important representatives of the so-called necrophages but also caring parents who together actively look out for their offspring aka larvae. Together with flies, they are some of the necrophages that appear the quickest on animal carcasses. 

Both male and female beetles bury the carcass together so that the female can lay the eggs in the surrounding soil. Once the larvae hatch they are fed by both parents with the decaying carcass meat. This form of active caring and feeding the offspring is very rare in insects. Once the larvae grow older, they feed themselves, pupate, and give rise to the next generation of carcass-consuming burying beetles.

(Image credits: James Lindsey at Ecology of Commanster)

Freeze tolerance and freeze avoidance via metabolic adaptations: the common lizard

The common lizard (Zootoca vivipara), also called viviparous lizard, is a Euroasian lizard found across Northern Europe through Central Asia. It lives farther north than any other species of non-marine reptile, and is the only lizard found in the Swiss National Park. Its small size and brownish colour allow it to disguise quite well. They are exclusively carnivorous and feed on flies, spiders, and insects.

Due to the cold, freezing temperatures, they have to survive in, they have developed metabolic adaptations for both freeze tolerance and freeze avoidance: They increase their anaerobic metabolism by 20% when compared to other periods of the year, i.e. they activate their lactic fermentation pathway leading to an increase of lactate concentration (>34% in winter). Additionally, their glucose concentration increases by which 245% in winter which serves as an antifreeze and metabolic substrate. However, “concentrations of alanine and glycerol, commonly used as antifreeze by many overwintering ectotherms, do not increase during winter” (Voituron, Hérold, Grenot, 2000).

Due to the cold Alpine climate, the lizards are viviparous and only produce a small number of offspring. The young hatch from the eggs within their warm mother’s womb. Young common lizards are darker than their parents.

Rain, ice and snow: How the grass frog copes with the harsh Alpine climate

The grass frog (Rana temporaria) also known as common frog or European common frog is a nocturnal animal that occurs in meadows and woodlands throughout Europe, from northern Scandinavia all the way to the far east as the Urals, except for most of Iberia, southern Italy, and the southern Balkans. In the Swiss National park it lives at an altitude of up to 2500m. The colouring meant to camouflage can vary from grey or brown to reddish brown or olive with dark spots on its back and its white or yellowish underparts.

In the coldest months, they hibernate in running waters, muddy burrows, or decaying leaves and mud in ponds. Given the harsher conditions in the Alps, in some cases, they might not emerge until early June. To sustain their oxygen needs during these cold, motionless times, they absorb oxygen through their skin. While completely submerged in water, all of the frog's respiration takes place through the skin. This is possible because the frog’s skin is composed of thin membranous tissue that is permeable to water so gases (i.e. oxygen dissolved in the water) can readily diffuse into the frog’s blood vessels. Their skin doesn’t contain the protein keratin which is found in the hair, fur, scales and skin of many other animals; lacking this protein, the frog’s skin is thinner. When the frog is out of the water, mucus glands in the skin keep the frog moist, which helps absorb dissolved oxygen from the air. Being active during the night also avoids sun exposure which can dry the skin. The frogs also drink through their skin.

During the spring, changes in external factors like rainfall, daylight, and temperature, cause the frog's pituitary gland to produce hormones which stimulate the production of sex cells (eggs in females, sperms in males). In April and May the female lays up to 3000 eggs in water holes and bogs. Only a very small fraction survive and become adults because birds especially prey on them. At the age of three, the frogs return to their birth side. Males return first to attract the females with their low-pitch growling croak.
Habitat loss (ponds, wetlands) and a number of diseases have caused the decline of grass frog populations across Europe in recent years. Many garden ponds are also not designed with amphibians in mind. Adding ramps, ladders or overhanging plants to garden ponds can enable the frogs and other amphibians to get in and out of the ponds easily.

Specialists in mountain lakes: the lake trout

These so-called pre-Alpine or Alpine rim lakes, left behind by the glaciers at the foot of the Alps, are the ideal habitat for the lake trout (Salmo trutta lacustris). In 2003, lake trout were recorded in 106 lakes, 55 of which are located at over 800 meters above sea level and are thus referred to as alpine waters or mountain lakes.

Lake trout prefer cool, clear water between 10 and 15 degrees Celsius. In most mountain lakes, this temperature is maintained even in hot summers. They also spend most of their time in large, deep waters.

Lake trout mainly hunt calorie-rich schooling fish such as whitefish or char in open water. Occasionally, lake trout also catch minnows or bullheads in the shore zone. With their coloring, lake trout are adapted to living (and hunting) in open water: They have silver flanks, a white belly and a dark back. If the trout’s prey is swimming below the trout and looks up, it will see a white trout belly that looks like the sun. If a fish is cruising above the trout and looks down, it will see a dark trout back that resembles the bottom of the lake. In smaller, shallower lakes, the trout retains its yellow to brown color with red spots and thus looks like a brown trout.

(Image credits: Ryan Marchese)

The comeback of an important predator - from extinction to reintroduction: the lynx

Hunted to extinction in Switzerland in the early 1900s, a successful reintroduction program facilitated the comeback of the lynx (Lynx lynx). In the 1970s, 14 lynx were transferred from the Carpathian Mountains in Eastern Europe to the Swiss Alps. Nowadays there are about 250 of these wild cats in Switzerland, split into two main populations – one in the northwestern Swiss Alps and the other in the Jura mountains where they prefer higher areas and open habitats. Additionally, in 2001 six lynx were “transferred from the northwestern Swiss Alps to the eastern side, but scientists fear that the lack of contact between the separate populations could lead to a decrease in the gene pool, threatening their long-term survival in the wild” (swissinfo.ch).

Lynx are principally nocturnal and solitary beings except in the March/April mating season when they can also be active during the day. They are territorial; a female covers a range of 50-150 km², and a male a range of 100-250 km². Individual lynx rely on scent marks and call communication to define their territory’s boundaries. Between adult individuals, these can mainly be heard during the mating season, and a different call is used for communication between females and their kittens.
The standard litter, born between late May and early June, has two kittens who stay with their mother for ten months. During their first 2 months, they rely on their mother's milk and after that, they can follow the mother to a kill site.

As a predator, the lynx plays an important role in this large-scale ecosystem. Hunting small cloven-hoofed animals such as roe deer or chamois, it can influence their population, behaviour and spatial distribution. This in turn reduces browsing on young trees which then promotes the regeneration of the forest. White fir or oak, for example, suffer particularly from browsing by deer. Moreover, a predator does not only eat prey. When lynx limit the population of grazing deer and chamois, vegetation has a chance to grow and not be overgrazed.

As a predator, however, the lynx is not always welcome by everyone and is still killed illegally. Conflicts occur mainly between lynx and hunters fighting over prey. In other cases, lynx cause discontent among farmers when they kill livestock, but the government compensates farmers for the lost livestock.

Slowing down for hibernation: Alpine marmots

Alpine marmots (Marmota marmota) can be found in alpine meadows and subalpine grassland where they build burrows and 1 to 2m long tunnels to protect them from their foes but also for hibernation in winter. Different burrows are used for summer and winter. A fun fact worth sharing is that the thumb of the Alpine marmot has a nail for digging, while the other digits have claws.

At the end of September, marmots retire to their winter burrows. They close the entrance of the burrows with grass and hay and then go into hibernation. On average they spend 6 to 7 months in hibernation.
During this time all bodily functions slow down considerably. Their body temperature drops to about 3 to 4 C but every 10 days or so their temperature rises to 38 C for 2 days.
There is no clear explanation for this rise in temperature yet, but it is thought that this process prevents nerve cells from dying due to inactivity and overall stops the animals from freezing during the winter. Their stored fat and huddling together keep them warm and increase their chances of survival.

Not only during hibernation do Alpine marmots adapt their temperature. Scientists believe that during the day, these marmots lie on flat rocks under the sun to lower their body temperature and to get rid of parasites and not to sunbathe, as is commonly believed.

The mysteries of the Mountain clouded yellow

The mountain clouded yellow butterfly (Colias phicomone) is found in alpine meadows between 900 and 2500m altitude clearly making it a butterfly adapted to the high mountains. In warm, sunny weather, they fly erratically over open grassy areas but in cool or cloudy weather they rest on the ground to warm up.

The dark green caterpillar lives on horseshoe vetches, bird's foot trefoils, clovers and other leguminous plants. The species hibernates in larval form and completes its development the following spring when the caterpillars form their cocoons between May and June. In July or August the butterflies emerge from the cocoons. The male and female adult butterflies differ a bit in colour; while the female is creamish-white, the male is greyish-yellow.

Colias phicomone is listed as a nearly threatened species by the International Union for Conservation of Nature (IUCN) and its main threats are tourism (skiing, other infrastructure) and overgrazing by livestock.

There is not too much information about the mountain clouded yellow in the literature, which means that there is still a lot of room for research on this species and its niche.

(Image credits: Harald Süpfle - Own work, CC BY-SA 3.0)

Cracking the nut: How nutcrackers feed themself while also regenerating the forest

Eurasian nutcrackers, also known as spotted nutcrackers (Nucifraga caryocatactes) are members of the cow family (Corvidae). They fly over the mountains of central and southeast Europe, including southern Scandinavia and European Russia, and north and central Asia, including Japan, Taiwan, China, and the Himalaya.

They feed on cembra pine seeds. Holding the cone with their toes, they extract the seeds with their sharp beaks. They can store up to 100 seeds under their tongue in a small sublingual pouch where they keep them until they can plant, i.e., bury them, miles away from where they found them. 

During the autumn, each bird hides pine nuts for the winter and spring all over the forest. Once the nutcracker has chosen a spot to hide a small catch of seeds - 3 to 5 per spot - similar to a farmer, the nutcracker swipes his beak over the patch of soil it has chosen, places a few seeds in the through, and covers them up with soil. One bird can hide almost 100,000 seeds per year. Remarkably, the nutcracker finds 80 percent of these seeds again later. How exactly nutcrackers find such a larger percentage of hidden food again remains a mystery. The remaining 20 percent are a gift to the forest as they grow into young cembra pines all over the forest. This way, the pine manages to disperse and reproduce, and eventually its offspring grow into adult trees that can feed more nutcrackers. 

Preparing extensive food caches allows nutcrackers to nest earlier than most birds. They begin in February, which in turn means offspring are old enough to participate in the late-summer seed harvest. Nests are built in conifer trees, such as the limber pine, and both parents feed and care for their young.

Perhaps, one thing we can learn from the nutcrackers is the following: Look out for yourself but don’t forget to give back to the community so the community also gives back to you. 

Studying the red deer antler for bioinspiration

Red deer (Cervus elaphus) inhabit most of Europe, the Caucasus Mountains, Anatolia, Iran, and parts of western Asia. They are another resident of the Swiss National Park, drawn to this habitat due to its tranquility and food availability. Usually deer live in herds, except during rutting season and when the hinds (female deer) separate from the herd to give birth. 

In their first year, fawns (young deer) have no antlers, after which their antlers grow annually between March and July. Antlers, formed of bone, serve both to impress and to fight. New antlers are protected by a soft, blood-filled bone-forming called the “velvet”, which is shed once the antlers have grown to full-size. Males also rub against trees to shed the velvet, which leads to minor bleeding incidents and earth remains to stain the antlers and give them a brownish color. 

The antlers are adapted for close-range fighting and body-temperature regulation and exhibit characteristics of impact resistance, wear resistance, and heat dissipation due to their buffering structure - a fenestrated network particle microstructure and large surface area. This structure may inspire the design of thermal management materials made out of Aluminum-Silicone single bond composites. 

Integrated compass? How the red fox might be able to sense the Earth’s magnetic field

The red fox (Vulpes vulpes) is distributed across the entire Northern Hemisphere - North America, Europe, Asia, and parts of North Africa, and also widely distributed in the Swiss National Park. ‘Smart as a fox’, as the saying goes, red foxes use over 28 different vocalizations and facial expressions to communicate with each other. They also rely on scent marking through urine, feces, and sac secretions. 

Due to the disappearance of the wolf, lynx and bear, the fox has become the largest predator here, mainly feeding on ungulate carcasses, worms, mice and marmots. 

Apart from a great sense of hearing with its large ears, recent research suggests that the fox also uses a magnetic sense to detect its prey. When jumping into the snow to catch a mouse, foxes prefer to jump toward the northeast (about 20 degrees off "magnetic north" — the "N" on your compass). In doing so, they achieve a much higher kill rate than when they jump east, south, or west. 

This hypothesis has not been confirmed yet and scientists have not detected any special organ or tissue in the fox that could potentially measure the Earth’s magnetic field. It seems like foxes can measure the distance between themselves and a mouse under the snow in the following way: “When a fox hears a sound under the snow, she searches for that sweet spot where the angle of the sound hitting her ears matches the slope of the Earth's magnetic field. When the two are in alignment, then — like a treasure map marked "X" — she knows exactly where to go! And 73 percent of the time, she's exactly right.”

Light as a feather, white as the snow: the rock ptarmigan

The rock ptarmigan (Lagopus muta helvetica) is the only bird that lives above the Swiss treeline in winter; however rock ptarmigans are distributed from the Arctic to Subarctic Eurasia and North America (including Greenland) on rocky mountain sides and tundra. To store enough energy and survive the cold, the birds eat large quantities within a short period of time, followed by a resting period in a kind of “igloo”, a snow hollow that acts as a shelter. In winter, their main foods are twigs, buds, and berry-bearing shrubs while in spring, summer, and autumn their varied diet includes leaves, flowers, berries, and seeds of a wide range of plants.

Their plumage changes according to the season to provide better camouflage: pure white and thick in winter and greyish-brown in summer. The coloration also differs between males and females. Their legs are covered with feathers all the way to their toes to keep them warm in winter and allow them to walk over snow. They are very lightweight, so they don’t sink so easily into the snow.

Their shallow nests are made out of plant material and feathers and are usually laid in the open and sheltered by a large stone or shrub.

Not scared of heights: The snow vole

The European snow vole (Chionomys nivalis) inhabits mountainous ranges in southern and eastern Europe and southwest Asia. In Switzerland snow voles live above 1000m altitude but they have even been found at altitudes above 4000m. They usually live in rock crevices but in winter, they live below the snow that acts as insulation and protects them from their foes.

Because this species is distributed in different altitudes and tends to have stable populations, the snow vole can serve as a bioindicator for environmental quality for alpine ecosystems. The cumulative environmental impact on snow vole populations can be evaluated by studying chromosomal aberrations, karyotype, morphophysiological indices, and ecotoxicological data, amongst others.

For example, researchers from the University of Zurich studied how snow voles at an altitude of 2000m near Chur responded to several consecutive winters with early snowfall. The researchers concluded that given this selective pressure, “voles whose genetic make-up led to a lower body weight were the fittest. [...] The reason: Smaller voles are fully grown by the time the weather conditions deteriorate [i.e.,] lighter snow voles are fitter, not larger ones”  (University of Zurich, 2017).

Hidden in the dark but still detectable by its hoot: the tawny owl

The tawny owl (Strix aluco) is a nocturnal bird of prey found throughout Europe, Western and Central Asia, and North Africa, primarily in deciduous and mixed forest but they can also inhabit coniferous forests, taiga, and riparian forests. In Switzerland they are found at 1500 meters above sea level in woodlands as well as cities, especially cities with natural forest patches. They nest in tree cavities but also in buildings, and prey on rodents, young rabbits, small birds, frogs, lizards, crustaceans, earthworms, and beetles. In urban areas, they feed on birds more frequently since they are easier to come by than other animals.

Tawny owls tend to live monogamously and pairs live together most of the time. However, from July to October, mates will roost separately during the day, and in winter, they will spend more time roosting together near their nest site.

Like other owls in Switzerland, tawny owl males use hooting calls to mark their territory and attract females. Since these owls mate for life, they have to be able to distinguish their mate from competitors so every owl has an individual identification call. Males and females also have a special call to express aggression towards competitors - “coo-wik” - and a shorter contact call for their mate - “kewick".

Admirable leadership and quick adaptation skills: the wolf’s return to Switzerland

In the 17th century, the way humans perceived their relationship to wolves (Canis lupus) in Switzerland changed dramatically as the increase of livestock farming brought about more wolf attacks in search of food aka the livestock. Wolves were considered malicious and merciless and increasingly hunted until over 100 years ago the last wolf in Switzerland was killed.

But in the past 20 years, wolves have managed to cross the Swiss-Italian border and reestablish themselves in Switzerland. A significant factor facilitating their return was the expansion of the forest. While in 1840, 20% of Switzerland was covered in forest, today 30% are forest cover. This has led to an increase in prey animals for the wolves. Today there are about 30-35 wolves in Switzerland.

Moreover, the wolves’ strong ability to learn and quickly adapt in any habitat - be it mountain, forest, or urban area- allowed them to reestablish their hunting grounds in Switzerland quite easily. They are found mainly in the less populated Alpine region and in the Jura.
Additionally, their remarkable leadership skills leave much for humans to learn. Johnson (2010) created a short list establishing how common characteristics of a wolf could be transferred to make an agile human leader:

Wolves vs Agile Leaders:

Sense of Urgency vs Quickness/Fast Action

Insatiable Curiosity vs Change/Openness

Patience vs Flexibility

Strategy & Planning vs Proficiency

Teamwork vs Teamwork

Wolves Never quit vs Consequent and Self-Awareness

The wolf has a naturally regulating effect on the forest’s animal population. Deer and roe deer, for example, move around more to keep away from the wolf and do not always eat the young shoots in the same places. This gives the vegetation more time to grow back, and erosion and flooding are prevented in a natural way. Other creatures such as insects, fish, birds and humans also benefit from this. Unlike human hunters, who always take a killed animal out of the forest, the wolf usually does not eat the entire prey. The scattered carcass parts left behind by the wolf are a food source for many organisms and destructors (bacteria, fungi, worms) decompose the remaining carrion into inorganic substances that plants can use.

However, the comeback of the wolf has been quite controversial, and for instance, hunting licenses are given out when wolves kill 35 animals over a four-month period, or if they prey on 25 animals in a single month. A recent study by a University of Zurich team found that one-third of the Swiss landscape makes for a suitable habitat for the wolf but only in 6% of that land did people show a positive attitude towards the wolf.

Spiders without a spiderweb in the mountains: the wolf spider

Wolf spiders (Lycosidae) form a family within the order of web spiders, the majority of which hunt without a web, instead ambushing their prey and catching it in one leap. Wolf spiders are mainly found in the spring at the edge of forests. Near bodies of water, they can often be seen running on the water using tiny hairs on their feet to stay afloat. They are found all over the world and in Central Europe they appear in plains and foothills at up to 800 m above sea level.

Free-hunting species like the wolf spiders see very well and can often distinguish colours. To attract females, the males wave their palps and attract attention with dance-like movements. Therefore, their palps and legs are usually strikingly coloured. Each spider species has its own dancing and waving behaviour.

The females carry their eggs in a so-called cocoon. When the young have hatched from the eggs, they cling to the mother and are carried around for a few days, i.e. the mother has a backpack of young with her. After about a week, the young are independent.

Ants: Architects, artists, agriculturalists

Ants (Formica) are an ecological indicator of a healthy woodland ecological community. There are 131 species of ants in Switzerland, for example, the red wood ant (Formica rufa) and narrow headed ant (Formica exsecta). 

 Anthills have already served as inspiration for building design but they are also works of art. Red wood anthills consist mainly of spruce needles and can be up to one meter high, while the ant hill of narrow headed ant is made up of dry plant material.

While one might assume that birds would recognize and avoid ant nests,  some birds sometimes voluntarily sit on top of a nest, and spread their wings. When ants come out to defend their territory, they spray the birds with formic acid, which helps the birds to combat pests. This practice is called “anting”. It might not really be a “win-win” situation, but at least the birds don’t seem to prey on the ants.  

Apart from working on nest construction and defending their nest, some ants are also in charge of ‘milking’ aphids (yes, it seems like not only humans practice agriculture). Using their legs, ants stroke the aphids’ back so the aphids excrete honeydew, a precious food for the ants. In return, the ants protect the aphids against predators such as ladybirds.

Wood ants also help to disperse seeds. This form of seed dispersal is known as myrmecochory. The seeds of plants like dead-nettles, snowdrops, corydalises and violets have 'elaiosomes', i.e., fleshy structures attached to seeds. Ants collect these seeds, bite off the actual seeds and only consume the nutritious elaiosome. In this way, the actual seeds are dispersed and can germinate there.

FLORA

Armillaria: Causer of Life and Death

Armillaria is a genus of parasitic fungi that attack the roots of trees and decompose them. In commercially used forests, Armillaria are considered a pest, but not so in natural forests. Here, they attack dead and living wood. They slowly infest and decompose the tree roots by interrupting the trees' water and nutrient uptake, which can kill weak, older trees, but young trees can also be attacked. As trees weaken and die, gaps in the forest are created where new trees can grow, thus 'rejuvenating' the forest. Deadwood also provides a habitat and food for several animal species. Armillaria are therefore an important part of the ecosystem because - together with other fungi - they maintain the cycle of life and death. 

The organism reproduces only via the root system and spreads underground via a huge network of fungal threads, also called mycelium, so their light-coloured, above-ground fruiting body is hardly visible. 

Armillaria thrives in northern temperate zones in North America, Europe, and northern Asia. The largest living organism on earth is the Armillaria ostoyae in Oregon, USA. Mostly with its mycelium, it spreads underground over an area of nine square kilometers (= 1,200 football fields). Its age is estimated at 2400 years. Armillaria ostoyae also exists in Switzerland, and one Armillaria ostoyae lives on an area of almost 50 football fields in the National Park in Graubünden. Its age is estimated at 1000 years.

Edelweiss: Surviving a harsh environment with a furry covering

Edelweiss (Leontopodium nivale), the symbol of the Alps, is perfectly adapted to life in the mountains. However, the plant does not only grow in the Alps, but also in the Jura, the Carpathians, the northern Balkans, the northern Apennines, and the Pyrenees.

The plant is covered with a layer of white downy hairs to prevent evaporation of moisture and at the same time, these tiny hairs collect air bubbles to protect the petals from burning in the sun or freezing in the harsh environment in the heights. The downy hairs also protect the plant against ultraviolet radiation. Cobweb houseleek (Sempervivum arachnoideum) uses the same trick as the edelweiss.

Interestingly, you won’t find edelweiss in the Mont Blanc area, neither on the Swiss nor the French or Italian side of the massif. This is because the Mont Blanc consists of siliceous, acidic rock which edelweiss doesn’t like. If you wander towards the Matterhorn, the soil changes to limestone soil in which these furry flowers thrive. Especially near Zermatt the edelweiss is very common.

Fire, drought and snow resistant: the larch

Larches (Larix decidua) are coniferous trees native to mountainous areas in central Europe, i.e., the Alps, the Carpathian Mountains, and the Pyrenees. They are also cultivated in Canada and the United States. In Switzerland they are especially found in the region of the Engadin and Valais.

Most people believe that all conifers are evergreen trees but the larch is actually a bit different in this regard: the larch’s needles come out in spring, turn golden in autumn, and are shed in the fall. The big question is, why are larches deciduous, unlike other conifers?

The reason deciduous plants change colours in the autumn and shed their leaves is to save nutrients that can then be used later - in spring. As it gets colder and days grow shorter, the chemical machinery for photosynthesis breaks down, and those chemicals (mostly nitrogen) are drawn out of the leaves and stored elsewhere in the tree, mainly the roots. Thus the needles become golden-coloured. This ability to recycle nutrients is very important in nutrient-poor environments. Shedding leaves is also an advantage in snowy climates: bare branches are less likely to break under heavy loads of snow compared to trees with needles during the winter. Its deciduous nature also makes larches more resistant to fire during dry months in the fall. And, their bark can be as thick as 30cm which also gives them protection against lightning and wildlife damage.

It is not clear whether the following also applies to larches in Switzerland but a research team from Nagoya University (Japan) found that “root development in larch trees in eastern Siberia [is] sensitive to the soil water conditions. As larch species are drought-tolerant, root development depends on the soil moisture conditions [...]. Under wet conditions the larch roots [tend] to develop in the surface soil layer rather than deeper layers. This indicates that larch can change the distribution of its roots in the soil, as an adaptation to annual changes in soil water conditions (drought or waterlogging) caused by [the] thawing of the permafrost. The root distribution may also be affected by the soil water conditions in the previous year, through a ‘memory effect’.”

The advantage of being small: Moss campion

Moss campion (Silene acaulis) also known as cushion pink grows in compact cushion-like forms on open grassland and scree (limestone and dolomite) throughout the northern arctic and the high mountainous areas of Europe and North America.

Even though being small is not always beneficial, it is of advantage for this small plant in the Swiss Alps. The little ground-hugging mounds only leave the small leaves exposed to the cold Alpine weather. The flower buds are protected among the leaves until July or August when the little pink flowers bloom on 3 cm long stems. The flowers are female, male or hermaphrodites.

Moss campion is also called a compass plant because the flowers appear first on the south side of the cushion. The full cushions can reach up to a diameter of over a meter. It takes hundreds of years for such a cushion to be large enough to cover a square meter.

The stems and leaves are sticky, which may prevent ants and beetles from climbing on and in the plant easily. The closed form of moss campions also allows them to retain water and heat and whilst dead plant material is recycled i.e. broken down and converted into a new food.

Nymph-like name and oak-like leaves: The mountain aven

Mountain avens (Dryas octopetala) are long-lived evergreen shrubs in the rose family (Rosaceae). Their eight-petal lobed leaves look like certain oak tree leaves, so they were named after dryads, wood nymphs of Greek mythology.

As a genus, Dryas are widespread throughout mountainous areas, mainly growing on limestone, in the entire Arctic, such as Great Britain, Scandinavia, Iceland, the Alps, the Carpathian Mountains, the Balkans, the Caucasus, and even Alaska and Canada. It is one of the most widespread plants in the Swiss covering alpine meadows. 

Their low-growing, short woody stems along the ground help prevent erosion. Their small, thick, waxy leaves are covered with hairs on the underside. This limits water loss when soil moisture is low and physical damage from cold and icy winds. Their feathery seeds make use of the wind for seed dispersal so they don’t depend on the few animals living on high alpine meadows. Plus, airborne dispersal can be far and wide. 

The flowers of mountain avens practice heliotropism, i.e., they track the movement of the sun across the sky during the day. Most plants do this to reduce the amount of solar radiation hitting their flowers or leaves, but mountain avens seem to do this to maximize the amount of sunlight reflecting off the petals and onto the pistils at the center of the flower. Flowers that track the sun are warmer and their pistils develop faster and produce heavier seeds than those that are shaded.

Fossils of Dryas plants give cues of past episodes of climate change and shifts in arctic-alpine vegetation. As the climate of the northern hemisphere began to gradually warm in the Pleistocene and the latest Ice Age went into retreat, tundra turned into forest. However, the warming was interrupted for periods of 300-1000 years during which arctic tundra vegetation set foot again in areas that had been turning to forest cover. Ecologists refer to these periods as the Older Dryas (approximately 13,800 years ago) and the Younger Dryas (11,500-12,800 years ago) because of the prevalence of Dryas fossils (Source: U.S. Forest Service).

As global temperatures keep rising, mountain avens will be forced to spread farther north and higher up to find the conditions they need for growth, perhaps testing the edge of land.

Extreme adaptations: How Norway spruce adapt to snowfall and drought

Norway source (Picea abies) found in the mountains and boreal forests of North, Central, and Eastern Europe. While they are native to this region, they are often planted for their wood. Norway spruce are quite rare in the Swiss National Park, however on the shady slopes of Engadine valley, they appear in mixed forests with larches. 

Norway spruce grow straight and fast. They require little light for germination and growth which gives them an advantage over other pine trees that require a lot of light. However in some places, spruce growth may be stunted by browsing. 

In areas with a lot of, such as to the south of Punt Praspöl, Norway spruce show a growth form adapted to large amounts of snowfall: They tend to have thinner trunks and short branches on which snow cannot accumulate. In German these trees are called «Schlangenfichte» (snake-spruce).

Apart from adaptation to snowfall at higher altitudes, Norway spruce might also have the ability to adapt to more frequent and intense droughts happening more and more in Europe. A team of scientists in Slovenia demonstrated that Norway spruce seedlings from a warmer climate at low altitude (410m above sea level) when under drought stress performed a conservation strategy, accumulating high amounts of abscisic acid, This in turn signals the plant to close its stomata faster to prevent the plant from withering.Seedlings from a cooler provenance from a higher altitude (931m above sea level) “were not so sensitive to the drought and the plants’ water supply and photosynthetic performance remained significantly higher. These findings indicate that a higher drought resistance in ‘cool’ provenance could be related to greater amounts of proline amino-acids, which are accumulated from the beginning of the drought simulation [...] resulting in increased stress tolerance.”

The panther cap: a poisonous mycorrhizal partner

The cosmopolitan Aminata mushroom is native to conifer and deciduous woodlands throughout the Northern Hemisphere, also including higher elevations of warmer regions in Asia, the Mediterranean and Central America.

The poisonous fly agaric (Amanita muscaria) also called fly amanita is familiar to most people from childhood. Less well known, however, is the poisonous panther bulb (Amanita pantherina) also known as panther cap, false blusher or the panther amanita with its brownish-grey to yellow-brown hat, striped edge, white warts and thickened bulb. They can be found from spring to late autumn in the forests of the foothills of the Alps where they like to grow on sandy soil. Like all mushrooms of the genus Amanita, they are ectomycorrhizal fungi, i.e. they form symbiotic associations with deciduous trees, especially beech, and coniferous trees. They derive photosynthesised nutrients from trees and provide soil nutrients in return.

The body of the mushroom contains the psychoactive toxins ibotenic acid, muscimol and muscazon. Like fly agarics, panther caps therefore cause severe poisoning affecting the stomach, intestines and nerves, which can even lead to hallucinations. The ratio of ibotenic acid to muscimol depends on season, age, and habitat.

Not all Amanita fungi are poisonous though. For example, the grey spotted mushroom (Amanita excelsa) or pearl mushroom (Amanita rubescens) are valued edible mushrooms.

Not a rose but a rhododendron

While the name comes from Ancient Greek “ῥόδον rhódon” which means “rose” and “δένδρον déndron” which means “tree”, rhododendrons are actually not roses but evergreen shrubs that can grow up to one meter high. However, they are often referred to as alpenroses.

Globally, there are over 1000 rhododendron varieties. In Switzerland we find for example the Rhododendron ferrugineum with rusty spots on the leaves’ underside (in Latin ferrugo = rust) which flowers from June through August and is the most common alpenrose in Switzerland. R. ferrugineum prefers damper and shadier locations and humus-rich soils. It is never found on limestone except where the soil is so leached that it already is acidic or unless there is an accumulation of peat above the substrate.

One the other hand, the rarer hairy alpenrose, Rhododendron hirsutum, grows at higher elevations among limestone rocks and in and around forests and flowers from May through July. While it prefers calcareous soils, it can also grow on slightly acid soils. While in the Alps its population is quite stable, it has declined in Croatia where it was widely collected from medicinal value, but it is now a protected species there.

While it is permitted to pick rhododendrons in Switzerland (while edelweiss and gentians are more threatened and thus forbidden to pick), the blossoms as well as the leaves and pollen of these alpenroses are quite poisonous. They contain a toxic compound called andromedotoxin (also known as grayanotoxin) which, depending on the dose ingested, can overstimulation of the central nervous system with symptoms like low blood pressure and cardiac rhythm disorders and nausea and vomiting.

Humans are not as susceptible as other species to the toxin that have died after ingesting this toxin such as grazing animals, household pets and some species of honeybees. However, the toxin doesn’t affect bumblebees and these animals are more efficient in pollinating rhododendron flowers, so it could be that the plant produces toxins in order to favor the bumblebee over other pollinators and improve fertilization rates this way.

The Swiss stone pine - an example of team effort  

Cembra pine (Pinus cembra), also known as Swiss stone pine or Arolla pine, is often found as far up as the forest limit. It grows in the Alps and Carpathian Mountains of central Europe, all the way to Ukraine and Romania. Adapted to extremely cold temperatures at high elevations, the cembra pine can withstand temperatures as low as –40°C. Hence, it may be a good tree to reforest high altitude regions. Its roots wrap tightly around bare rock and reach deep down cracks for water. The deep and vast network of roots can hold mountain slopes together preventing rockslides. 

The Swiss stone pine grows very slowly (it may take 30 years to grow up to 1.30 m) and hence it also has to save energy and can’t grow large seeds every year. Seeds are produced only every 6 to 10 years and about every 10 years, a large number of cembra pines ‘communicate’ (how exactly is still subject of research) to simultaneously produce large, heavy cones. 

Cembra pines also rely on nutcrackers for seed dispersal. Nutcrackers’ sharp beaks are ideal for picking out the nuts of the pine’s cones. They then bury the pine seeds as food reserves in fall. Since the nutcrackers plant the pine nuts in the ideal germination conditions at a depth of 3 to 5 cm in the soil and they also don't find all the nuts they hide the next spring, some seeds germinate and start growing into new trees. 

Swiss stone pine wood has not only been valued for architectural purposes but also for its health benefits. ‘You sleep better in a Swiss stone pine bed’ is one of them. A study by the Joanneum Research Institute showed that sleeping in bedrooms made out of Swiss stone pine wood promotes deep sleep and better relaxation in the night which in turn means a lower heart rate during the day. Even a pillow filled with aromatic Swiss Stone Pine wood shavings might help improve your sleep. 

(Image credits: By Terra3 - Own work, CC BY-SA 3.0)

An unforgettable vanilla scent above the forest limit: the vanilla orchid

As the name says, both the black and the rosy vanilla orchid (Nigritella nigra/rubra) belong to the Orchid family. You will likely come across them and perceive the flowers’ vanilla scent when walking through grassy, limestone meadows above the alpine forest limit between June and August. They can in fact be found all the way from the Alps to the Carpathians at altitudes between 1,000 and 2,800 meters.

The orchids and their pollinators are an impressive example of how through constant adaptation between different organisms plants and pollinators developed a mutual bond and dependence. The structure of the flower and the function of its pollination organs on the one hand and the anatomy and behaviour of the insects on the other hand adapted to each other in the course of time to create a sophisticated pollination mechanism which guarantees the reproduction of the orchid species.
The black vanilla orchids (Nigritella nigra) are mainly pollinated by butterflies, which are probably attracted to the flowers due to their vanilla scent. The butterfly’s proboscis is perfectly made to reach the nectar of the flowers. However, the rosy vanilla orchid (Nigritella rubra) reproduces apomictically (asexually), i.e., the embryos develop without prior fertilization from cells of the nucellus.

The main threats to these alpine jewels are hikers picking them and overgrazing, and, since this plant is a specialist and its biota is generally limited by low temperatures, climate change is also a major threat. It is very important to preserve the habitat of this species and its pollinators.

(Image credits: Daniele Pralong)

Longer summers, nutrient changes and range expansion: Gentians competing for space

The genus Gentiana is extremely diverse with over 200 species worldwide and distributed globally, mainly occurring in alpine regions. Individual species are adapted to their specific ecological niches (elevation, sun, soil and moisture).

Yellow gentians (Gentiana lutea) are a hardy plant, native to the Alps where they prefer the lime soils of moist, grassy meadows, slopes and fens at an elevation up to 2,500 meters. They prefer semi-shaded or no-shade areas.

They have a long, deep rootstock that can weigh up to 7kg to stay grounded when winds blow and the leaves and flowers are very close to the hollow stem. The perennial plant only flowers after about 5 to 7 years of age, sometimes not until after 10 years. It flowers from July to August.
The bitter glycosides gentiopicrin and amarogentin contained in Yellow Gentian roots and herbage are some of the most bitter natural substances known and used as essential oils and medicines.

A study conducted by a team from the University of Vienna and the Swiss Federal Institute for Forest, Snow and Landscape Research found that as temperatures rise, these plants as well as many other Alpine plant species face increased pressure at higher elevations. Due to climate change, the majority of alpine flora are slowly shifting their ranges to higher elevations, but at higher altitudes space is a luxury and competition with species already growing there is quite high.

When Alpine flora shift their ranges, we can speak of “winners” and “losers”. While climate change might allow some plants - the “winners” - to spread easier, like the yellow mountain saxifrage (Saxifraga aizoides), species that are adapted to cold and nutrient-poor conditions, like gentians, are the losers. This latter species, can’t grow stronger or taller with these temperature and nutrient changes. During potentially longer summers gentians would also be at a disadvantage because they would not be able to produce more seeds or daughter plants as other species would. The research team concluded that “if the competitive species win, then there will be a loss of biodiversity – at least on a small scale”.

(Image credits: Böhringer Friedrich)