Natural Features of Käsivarsi Wilderness Area

A ptarmigan in its summer dress standing on a stone next to the creek.

In Käsivarsi wilderness area, the great fells are reaching up to the sky. This realm of harsh winters and bright summers is home to species not encountered anywhere else in Finland.

Taking Care of Nature

Halti - the Highest Peak in Finland

The fells of the Käsivarsi region were formed when the Scandinavian Mountains were first thrust into the sky hundreds of millions of years ago. This is where the older bedrock foundation of Finland meets the newer Scandinavian Mountains' bedrock. Halti is the highest of Yliperä's fells. Its peak is actually in Norway, but the landmark is the highest point in all of Finland - 1,324 metres above sea level.

On the edge of the overthrust plate 

As the mountains were being pushed upward, newer rock was pushed on top of the older bedrock. This newer rock was schist, which was formed from deposits on the seafloor. The schist, which can withstand the weight of the overthrust plate, protected the weathered rock layers beneath it. Saana, Saivaara and other cliffs in the area are the edges of the overthrust plate.

The terrain in the Käsivarsi region is very rugged in many places. In the Arctic climate, the formation of rock fields is very common. Temperature fluctuations cause the rock surface to contract, expand and crack. Water freezes inside cracks in the rock and eventually splits them into boulders, which roll to the foot of the fells.

Large fells at the top of Finland

The conditions found in the Käsivarsi region are unique in Finland. The elevation and northern location of the region mean that it has one of the shortest growing seasons in Europe - only roughly 100 days a year. The average annual temperature falls well below zero. Thanks to the Gulf Stream, the climate in the Käsivarsi region and Northern Norway is warmer than other regions at the same latitude.

The edges of the Scandinavian Mountains also bring lime to the soil, thus promoting the growth of numerous plants that cannot be found anywhere else in Finland. Many rare plants in the region are protected.

In the upper fells of the Käsivarsi region are mountain plants, such as the glacier buttercup, hairy housewort and Arctic bellflower. The sulphur buttercup can be found in snowbed areas and Arctic arnica and snowy cinquefoil grow on calcareous rock walls. Numerous rare plants, such as the Alpine fleabane, woolly pussytoes and Lapland rosebay grow in the Käsivarsi Wilderness Area.

Treeless summits

The treeless summit is the prevalent vegetation habitat in the Käsivarsi region. Fell birch stands are only found in river valleys. The average treeless summit is 900–1,300 metres above sea level. A unique feature of treeless summits is the Arctic bell-heather heath. A heather plant, the Arctic bell-heather can be identified by its white, bell-like flowers and jagged shoots. Grassy heaths dominated by highland rush or sheep's fescue are also common in the middle oroarctic zone.

Heaths of eightpetal mountain-avens 

Finland's largest eightpetal mountain-avens heaths are found in calcareous areas of the Käsivarsi region. The eightpetal mountain-avens grows on dry knolls and fresh slopes. Water from the limestone bring moisture and nutrients to the meadow-like eightpetal mountain-avens heaths. These heaths are also an excellent habitat for many other fell plants that need lime, such as the moss campion, vanilla scented bog orchid, net-leaved willow and Lapland rosebay.  Rockiness, frost and snow create patterned grounds, snowbeds and rock fields, on which only mosses and lichens can survive. 

Moths and butterflies flying day and night

The vegetation in Yliperä's fell meadows provides sustenance for butterfly and moth species, whose juvenile phases are spent only on certain fell plants. The polaris fritillary larva feeds on the eightpetal mountain-avens and Arctic bell-heather. In the Kilpisjärvi area, 340 butterfly and moth species have been observed, 16 of whose entire population is found exclusively there. Named after the explorer Giuseppe Acerbi, the Arctic tiger moth (Acerbia alpina) also thrives on the highland plains of the Käsivarsi region. 

The butterflies and moths of the fell meadows take full advantage of the rare warm days and suitable conditions. Because the sun never sets during the summer, these lepidoptera fly at the most favourable times, day and night. However, many moth species do not fly until after midnight when the sun disappears behind the fells. 

Fell insects are often dark in colour and hairy, so that they can collect as much warmth from the sun as possible in their tiny bodies. Due to the short summer, the time for butterflies and moths to fly is usually July. The Annjalonji Specially Protected Area was established to secure the habitat of endangered butterfly and moth species, and no one is allowed to stray from the trails whatsoever during the summer months. 

The emblem of the Käsivarsi Wilderness Area is the ptarmigan

The emblem of the Käsivarsi Wilderness Area is the ptarmigan (Lagopus muta), which stay on their home fells the whole year round. In Finland, the range of the ptarmigan covers the fells of the Käsivarsi region and Northern Lapland as well as the higher fells in the Pallas-Yllästunturi and Urho Kekkonen National Parks.

The ptarmigan holds out in the fells the whole year round. In the winter, it eats dwarf willow and dwarf birch buds as well as berries and seeds exposed from the snow cover by the wind. The related willow grouse thrives in the shelter of fell birch stands. Its primary source of food during the winter is fell birch buds. In the winter, both birds spend their nights in a snow nest, which helps them to save their energy and protects against predators.

At first glance, telling the difference between a ptarmigan and willow grouse might seem difficult. However, the birds you see above the treeline are probably ptarmigan and those seen in the fell birches are willow grouse. The two birds can be easily identified by their distinct calls. The ptarmigan produce a series of guttural growls and clucks, while the willow grouse makes a repeated 'co-peck, co-peck' sound followed by a distinct chuckling noise. 

Both have snow white winter plumage. There are black feathers only on the tail, which can be seen while they are in flight. In the winter, the ptarmigan male can be distinguished by black stripes, which extend from its beak to its eyes. In the summer, ptarmigan can generally only be identified based on their habitat, even though the bird does have a characteristically slender body.  

The ptarmigan's summer plumage colours include subtle rock grey and brown tones, while the willow grouse has a russet colouring to its plumage. The ptarmigan relies on its camouflage, waiting until the last minute to conceal themselves from hikers.

Other winged denizens of the fells

Approximately 100 nesting bird species, a majority of which are migratory, have been observed in the Käsivarsi Wilderness Area. In the frigid, snowy winters of the Käsivarsi region, only a few bird species are able to survive. In addition to the ptarmigan, the willow grouse and gyrfalcon have also adapted to the harsh conditions.

Nesting bird species found in the Käsivarsi region include the snow bunting and Eurasian dotterel. The meadow pipit, Lapland longspur and northern wheatear are among the most populous species. A bird typically found in the fell birches of the Käsivarsi region is the bluethroat, the nightingale of Lapland. 

The ring ouzel is Finland's northernmost thrush species and one of the Käsivarsi region's more unique species. The ring ouzel thrives in the rock fields above the treeline, with a majority of the few hundred nesting pairs building their nests in the Käsivarsi region. The ring ouzel is very shy, but its presence can be detected by the call of the male. 

Northern waders, such as the dunlin, red-necked phalarope, bar-tailed godwit, purple sandpiper, Temminck's stint, broad-billed sandpiper and spotted redshank, are found here. A majority of some of these species nest in the Käsivarsi region.  Many birds of prey, such as the rough-legged buzzard, long-tailed jaeger and snowy owl, appear in large numbers and are linked to the population dynamics of the vole and lemming.


The common teal and Eurasian wigeon are two of the more common waterfowl found in the region. The long-tailed duck, velvet scoter and red-throated loon can also be spotted here. The Arctic tern makes its home in fell lakes. The white-throated dipper can easily be seen flitting about riparian areas.

Catching graylings

The waters of the Käsivarsi region's high fells are oxygen-rich, clear and barren. Salmon species thrive here. The Käsivarsi region is a fisher's paradise, with some of Finland's top spots for trout, Arctic char, whitefish and grayling. Grayling and northern pike can be found at elevations of up to 700 metres. The largest grayling specimens can weigh as much as 2 kilograms, while pike can even top out in the tens of kilograms. Trout live in all running water areas. Because many migratory fish species are currently endangered, it is recommended that, for example, all trout be released in order to preserve the natural fish stocks. 

A paragon of fish, the Arctic char, is specially adapted to cold waters. In the summer, it lurks in the colder depths of lakes. On calm summer days, it rises to the surface to feed on mosquitoes. At the end of the last Ice Age, the Arctic char was one of the first fishes to inhabit the cold waters found in the fells. As the continental ice sheet retreated, the land began to rise and the elevations of waterbodies changed. A barrier formed at Pihtsusköngäs that prevented species arriving after the Arctic char from making their way into these waters. Indeed, waters above Pihtsusköngäs today only contain a single fish species: the dwarf Arctic char.

The Arctic Fox is at Home on the Fells

A resident of Lapland, the Arctic fox, is today an extremely rare sight in Finland. Arctic foxes have succeeded to den for the first time in 25 years in Enontekiö fell-area, previously it happened in 1996 in Utsjoki. The highly endangered Arctic fox population in the North is now slightly growing in numbers after many weak years in the beginning of 21th century, currently it is estimated that there are ca. 450 Arctic foxes in Sweden, Norway and Finland. The return of  cyclic population change of small rodents has had a positive impact on Arctic fox population, lemmings and moles are important sources of food to Arctic foxes and also key species in the fell nature. Monitoring and protection work, that has been going for decades in the Nordic countries also plays a major part in helping the Arctic fox population. The most important conservation measures have been fox hunting and supplementary feeding in the fell nature.

The original habitat areas of the Norway lemming are also found in the Käsivarsi region. Norway lemming leave the shelter of their snowbeds to migrate, with some reaching as far as Rovaniemi. The last recorded migration of Norway lemming was in 2011. It has been 41 years since the last major migration. The disappearance of Norway lemming over the decades seems to also have played a role in the decline of the Arctic fox.