Battle of the foxes

Guest author: Samuli Karppinen

“It was the fifth red fox for the same day”. “Foxes are everywhere”, I thought numerous times during my summer job time in the region of Inari. I was amazed at the number of red foxes (Vulpes vulpes) present in the very northern part of Finland. Nearly every day and no matter where I went, I discovered foxes. I observed foxes close to settlements, and at the end of forest gravel roads. They were mainly lonely adults, but litters of the same year were common too. In addition, the number of red fox dens supported the idea that they succeed well in the northern part of Finland. The arctic fox (Vulpes lagopus) is adapted to life in arctic areas. In Finland, arctic foxes have bred in the regions of Inari and Utsjoki. Arctic fox populations are similar in size to those in Sweden and Norway. Population size at the end of the 1800s was estimated to be 15 000 individuals. At present, the size of the population is estimated to be only 120 individuals. Despite yearly sightings of arctic foxes in Finland, it is nearly 20 years since the last confirmed arctic fox litter. During the summer I began wondering how red foxes influence the declining arctic fox population?

The Arctic fox in Polar Park Norway. © Sari Holopainen

The Arctic fox in Polar Park Norway. © Sari Holopainen

Intensive hunting in the early 1900s was the ultimate reason for the collapse of the Fennoscandian arctic fox population. Even though arctic foxes were protected in 1940, the population did not return to its earlier size. There are several probable causes. Due to changes in reindeer husbandry, arctic foxes cannot exploit the same number of carrions. Global warming causes problems to arctic species and the arctic fox does not stretch the point. Climate change affects snow cover, which reflects on the amount of lemmings. Lemmings are a vital food source for arctic foxes. Arctic fox brood and litter sizes are bigger when the amount of voles and lemming are at their highest point. In addition, global warming is raising the tree line to higher altitudes on the fells. This improves the survival of red foxes in the areas inhabited by the arctic fox.

The red and arctic foxes cannot inhabit the same territory. Research has uncovered that red foxes colonize and annihilate arctic fox dens. The red fox is very adaptable to different habitats and competes for food with the arctic fox. The striking winning picture of the Wildlife Photographer of the Year 2015 –competition underlines the interactions between the two species. The arctic fox is smaller than the red fox and loses the competition for food and habitats. Exploring the number of litters in the last 20 years, it can be seen that while red fox litters have grown, arctic fox litters have declined. The first idea to prevent the spreading of red fox populations is extensive hunting. At the beginning of the millennium, red foxes were intensively hunted in the fell areas of Enontekiö and Utsjoki under the Naali Life – project. The catch quotas appointed by the Ministry of Agriculture and Forestrywere fulfilledvery well by hunters each year. Unfortunately, the hunting alone and the short hunting period in particular had hardly any significance for the arctic foxes.The hunting probably only improved the living conditions of the remaining red foxes and the population might even have strengthened.

Fox cub in Inari. © Samuli Karppinen

Fox cub in Inari. © Samuli Karppinen

Finnish hunters are active in culling semi-predators, like red foxes. It seems that Finnish hunters actively cull semi-predators up to the height of the Arctic Circle. Active culling does not occur in the regions of Inari and Utsjoki, at least in the same scales.Reasons for this are clear: hunters are less enthusiastic, distances are long, the road network is sparse, and snow coveris thick. Maybe hunters of northern Finland don’t feel that culling is as important as hunters in southern Finland do. Red fox culling has to be continuous and intensive year after year for it to have positive effects on the arctic fox population. In 2015, the Finnish wildlife agency, as a part of Management of invasive Raccoon Dogs (Nyctereutes procyonoides) in the north-European countries project, started a project to cull the raccoon dog population in Lapland. A similar project, focused on the red fox, could be a good motivator for local hunters to cull the red foxes.

Research has indicated that lynx (Lynx lynx) regulate red fox populations. Foxes do not succeed in areas where lynx populations are abundant. One of the reasons for red fox success in the fell areas could be a lack of lynx. Unfortunately, it is not realistic to expect that lynx could be the arctic fox’s rescuer. The EU-Life project SEFALO+ (Save the Endangered Fennoscandian Alopex lagopus) has shown that a combination of actions, supplementary feeding, red fox culling, and protection of dens, could cease the decline of the arctic fox population and even enhance it. Nevertheless, I began wondering whether all these actions to save the arctic fox population in the Nordic countries will merely delay their extinction? Their population is small and genetic variation low. Diseases may heavily impact such a small population. Another possible threat to the arctic fox is the occurrence of escaped farm foxes on the mountain tundra. They can breed with wild arctic foxes, but hybrids do not survive in the wild. There are many problems and threats, which Fennoscandian arctic fox population have to face to avoid extinction.


Frogs love beaver-created wetlands

Amphibian and wetland loss is occurring globally at an increasing rate. Since the 1900s, approximately half of the world’s wetlands have been destroyed. During this time up to two-thirds of European wetlands were lost at a regional scale. This trend is reflected by the fact that 23% of Europe’s amphibians are threatened.

Wetlands in the boreal region are frequently constructed through the damming activities of an ecosystem engineer, the beaver (Castor sp.). They create and maintain special habitats by constructing dams. Beaver-created wetlands are open and sunny due to tree felling and flooding-induced tree mortality. They produce large quantities of woody debris and detritivorous invertebrates, e.g. chironomids and Asellus. Beaver ponds contain structurally heterogeneous vegetation.

Beaver-created wetlands contain structurally heterogeneous vegetation, as well as open water areas. © Mia Vehkaoja

Beaver-created wetlands contain structurally heterogeneous vegetation, as well as open water areas. © Mia Vehkaoja

According to our new study beaver-created wetlands increase frog species heterogeneity and abundance. There are only three native anuran species in Finland (the common frog, the moor frog and the common toad), and all of them were found in beaver ponds. The moor frog (Rana arvalis) was only found in beaver ponds, where the common frog (Rana temporaria) was also most abundant. The common toad (Bufo bufo) prefers deeper wetlands than the other two species, but because beaver ponds contain both shallower and deeper parts, it was also found from the beaver ponds.

Beaver wetlands offer high quality habitats for anurans and facilitate the occurrence of moor frogs. The shallow and warm water areas accelerate the hatching and metamorphosis of tadpoles. The rich aquatic vegetation provides attaching places for spawn and protection against predators. The abundant vegetal detritus, zooplankton and aquatic invertebrates offer nutrition for both larvae and adults. In addition, beaver-created wetlands create overwintering habitats that are less likely to freeze down to the bottom.

Both the moor frog (Rana arvalis) and the common frog (Rana temporaria) are the most abundant in beaver ponds. © Mia Vehkaoja

Both the moor frog (Rana arvalis) and the common frog (Rana temporaria) are the most abundant in beaver ponds. © Mia Vehkaoja

Beaver facilitation includes both habitat amelioration and resource enhancement. Frogs are not the only group that is benefitted by beaver activity. Other such groups are ducks, bats, woodpeckers and many invertebrates. These ecosystem engineers could be used in wetland restoration, and furthermore the beaver clearly promotes amphibian conservation.

Urban runoff is processed in nature

An urban wetland in Nummela shows the way for new Finnish legislation

The citizens of Nummela in Municipality of Vihti have gathered to admire the new landscape. A verdant wetland has emerged at short notice. The wetland’s purpose is to filter out pollutants and nutrients washed off streets and buildings by stormwater. Since last autumn Finnish cities have been obligated to process urban runoff, which includes stormwater leading away from built areas. Nummela decided to solve this problem with the help of nature. But the urban runoff processes are not the reason why Nummela citizens are tempted to the wetland. The luxuriant wetland is a paradise for diverse fauna and flora, e.g. frogs and newts, and these new neighbours are the reason why enthusiastic outdoor exercisers have congregated at the wetland.

Extreme weather phenomena become more common with climate change

The Nummela wetland is just a trial, originating because of a huge problem looming in the background. In urban areas waters cannot infiltrate into the ground, but cause strong runoffs. Extreme weather phenomena are becoming more and more common with climate change, even in Finland. Torrential rains wash away nutrients and pollutants that have to be processed before they enter rivers, lakes and oceans. This is why the number of urban runoffs has continuously increased during recent years.

Most wetlands have been destroyed

Building small urban wetlands is an efficient way to process urban runoff. It is sadly ironic that development has moved backwards: during the last 100 years two-thirds of Europe’s wetlands have been destroyed. And now we are building them back.

Within cities wetlands filter rainwater that can’t enter the soil through the blacktop. Wetlands retain and process impurities occurring in water. These impurities will sink to the bottom in the wetlands and exit the cycle. From the bottom they can be removed for further processing. As for the nutrients, the wetland vegetation can use them for growth.

Tighten legislation can, at its best, bring beautiful nature for citizens to enjoy. Helsinki, the capital of Finland, has also established four urban wetlands. Their purpose is, in addition to processing urban runoffs, to mitigate flow of stormwater and store snow. Similar urban wetlands will be established in Finland in the future with the aid of new legislation. This way Finns will have new diverse recreational areas within reach.

Eradicating species – an occasional necessity

If Finland is to obey the EU strategy on Invasive Alien Species (IAS), 10 000 North American beavers (Castor Canadensis) are to come under the trigger. Why is this eradication necessary?

Although invasive alien species, e.g. the American mink (Neovison vison), the ruddy duck (Oxyura jamaicensis) and the Himalayan balsam (Impatiens glandulifera), may seem adorable and interesting novelties, they nearly always threaten the survival of native species. Invasive alien species are harmful to agriculture and forestry, and at their worst can even threaten human health. Sometimes we face the inevitable: the eradication of an animal or plant species.

The most efficient way to minimize the risks is to prevent it spreading to an area in the first place. Australia is probably the most famous example of preventing the spread of alien species, as they even clean the shoes of tourists at the airport before allowing them into the country. Unfortunately no nation has been successful in averting the spread of IAS.

Not that a tough fight isn’t being fought the new EU strategy on invasive alien species took effect earlier this year.

The main aim of the strategy is to aggregate a list of the most pernicious invasive alien species and to repulse them in different ways. Finland has 160 harmful IAS. Whether each of them will be on the EU’s black list remains unclear.

The North American beaver is first in line

The North American beaver is one of the most potential mammal alternatives for the list. The species was brought to Finland in the 1930s to save Finland’s beaver population. Back then the genetic differences between European and North American beavers were unknown, although we now know that the species differ even more than humans and chimpanzees.

The niches of both species are identical. They eat the same nutrition and their damming activities are the same. Both species have identical effects on ecosystems.

There are approximately 12 000 beavers in Finland. Most of them (10 000) are North American beavers, while European beavers comprise only a fifth of the North American beaver population. The North American beaver threatens the existence of the European beaver in Finland. It might eventually competitively exclude the European beaver. Adhering to the precautionary principle and seriously considering eradicating the North American beaver from Finland and Eurasia is essential. An eradication plan has nevertheless been conspicuously absent. An eradication plan for North American beavers would abide to the guidelines of both the IUCN’s and Finland’s National Strategy on Invasive Alien Species.

How to eradicate a species in practice?

A large scale eradication of the North American beaver is possible, at least in theory. Several possible methods could be used simultaneously, such as hunting, live capture, sterilization, reintroduction of the European beaver and population monitoring.

Beaver hunting is also financially tempting. Beaver furs have once again become popular in China, so their markets have a demand for beaver furs. After the sterilization or dead trapping of North American beavers, they should be replaced with European beavers.

But this is not a straightforward process. Although the two species differ genetically, they have a similar effect on the ecosystem. Beavers act as ecosystem engineers and benefit several other species in Finland and elsewhere. The present population size of the North American beaver ameliorates e.g. the green sandpiper (Tringa ochropus), the moor frog (Rana arvalis) and the Daubenton’s bat (Myotis daubentonii). However, if all North American beaver individuals were removed and replaced by European beavers, the eradication would be harmless to Finnish nature. Unfortunately, there is nothing to guarantee the success of the reintroductions.

Finland must begin eradication if the North American beaver is placed on the EU strategy plan on Invasive Alien Species. The activity of citizens and hunters will determine the eradication outcome. The Ministry of Agriculture and Forestry in concert with the Finnish Advisory Board for Invasive Alien Species are in charge of the decisions and eradication procedures.

Finland is a developing country when it comes to its fishing policy

Almost all of Finland’s migrant fish are threatened. At the moment the endangered fish species of Finland have no protection; they are like outlaws. For example the Finnish landlocked salmon (Salmon’s subspieces Salmo salar m. sebago only lives in inland waters) is more endangered than the Saimaa ringed seal (Pusa hispida saimensis). A study shows that only 0.04 % of the smolts survive and reach sexual maturity. This means that only one individual in 2500 smolts will spawn.

Almost all of Finland’s migrant fish are threatened. Luckily, the trout (Salmon trutta) is not yet one of them. © Mikael Kraft

Almost all of Finland’s migrant fish are threatened. Luckily, the trout (Salmon trutta) is not yet one of them. © Mikael Kraft

Additionally, the sea trout parr (Salmo trutta trutta) is critically endangered in Finland. Hydro-electric power plants previously destroyed the robust populations of the sea trout, but nowadays the main problem is fishing nets. Finland is probably the only civilised state where anybody can fish using nets. In other parts of the world fishing with nets is strongly regulated or banned completely. All the endangered species living in the inland waters of Finland, even the Saimaa ringed seal, face the same threat: fishing nets (both professional and free-time fishermen). The main problem with fishing nets is that they catch almost all the smolts, leaving no fish to spawn.

Finland is also the only nation in the world that allows fishermen to fish using massive trawls in inland waters. Finnish researchers are unanimous: our fishing policy is unsustainable. Policymakers don’t listen. Rather, they are against every positive development. In today’s world with the EU and other institutions, how is it possible that no one outside Finland is not reacting. If Finnish policymakers are this blind or spineless, maybe the EU could invoke for example the Habitats Directive (more formally known as Council Directive 92/43/EEC on the Conservation of natural habitats and of wild fauna and flora), and force Finland to alter its fishing policy. We have some successful example (the Przewalski’s horse returning to Mongolia, deforestation in Madagascar) of how pressure / help from the outside world has contributed to the preservation of species or ecosystems in developing countries. At least the EU should wake up now and prevent the local extinction of several fish species.

Further reading:
Salmi P, Auvinen H, Jurvelius J, Sipponen M (2000) Finnish lake fisheries and conservation of biodiversity: coexistence or conflict? Fisheries Management & Ecology 7: 127–138. DOI: 10.1046/j.1365-2400.2000.00183.x

Auvinen H, Jurvelius J, Koskela J, Sipilä T (2005) Comparative use of vendace by humans and Saimaa ringed seal in Lake Pihlajavesi, Finland. Biological Conservation 125(3): 381–389. doi:10.1016/j.biocon.2005.04.008

Hot spots of boreal landscape

The beaver (Castor spp.) is a known ecosystem engineer that modifies its environment quite drastically. It builds a dam and raises floodwaters into surrounding forests, killing trees, and releasing organic material into riverine systems and lakes. The rising water level changes both the abiotic and biotic conditions of a wetland. Many organisms, from water lice to water birds, benefit from these changes. Beavers facilitate these species by offering both nesting and sheltering areas in the form of low bushes and trees by the water’s edge, increased aquatic plant communities for nutrition, and ice-free water areas for extended periods.

Beaver-created wetlands are cyclic ecosystems. Beavers usually inhabit a site for one to three years and then move to the nearby site, where the whole process starts again. After the beaver has left the site, the abandoned site reverts quite slowly back to the original. So the beaver’s actions endure much longer than they occupy the site, and commonly they return to former sites within 10 years.


Beaver-created wetlands can be seen as a biodiversity hot spots. This pic is from eastern Finland. © Mia Vehkaoja

Beaver-created wetlands can be seen as a biodiversity hot spots. This pic is from eastern Finland. © Mia Vehkaoja

The beavers’ actions can be seen as quite sharp shifts in an ecosystem, but the very nature of the changes that the beavers create tends to be rather stable. As the beavers transform the ecosystem they also enable resilience in landscapes. Beaver-created wetlands increase the heterogeneity of the landscape, and can be seen as biochemical and biodiversity hot spots. They maintain several declining species, especially in the northern Boreal Hemisphere, where eutrophic wetlands are relatively rare.
The EU has an ongoing project called the Return of Rural Wetlands. The size of the EU funding in this project in Finland is a little over a million Euros. The other million Euros come from the Finnish Government and the rest from the Finnish Wildlife Agency. The aim of the project is to create a new frame and a good start for the future nationwide program for wildlife habitat conservation, restoration and re-creation. So people are creating new wetlands using tractors and diggers, and by bringing soil and water from elsewhere.

Beavers would do the same work for free. Instead of misspending lots of money on labor, expensive machines and moving earth, we could use some part of the funding to re-introduce the European beaver (Castor fiber) to a wider area. In this way we would save money, get the same results, if not even better ones, and help our original, once extinct species to recover. In addition, Finland would achieve the obligations of EU Inland Water Directive.

The new re-introduction of the European beaver project would involve the same interest groups as the Return of Rural Wetlands project. Some of the re-introductions could be conducted on state-owned lands and some on privately owned land. There are several local landowners involved in the Return of Rural Wetlands project, so there is a good possibility that they would be interested in the same kind of project as well. Regional hunting clubs would want to be involved, as beaver-created wetlands offer improved hunting and fishing opportunities, because their habitat engineering increases the number of game and fish species. It might be easy to get regional authorities and policymakers to engage in the project, because of the EU obligations that abide them. Furthermore, the policymakers would conserve the biodiversity of Finland, and gain the respect of The Finnish Association for Nature Conservation and the public. When all these interest groups are involved in and the role of power is divided to various levels, a revolution in wetland creation is possible. When such a project succeeds in Finland, it should be possible to implement it also in other EU countries.


The Mallard (Anas platyrhynchos) favors beaver-created wetlands, especially during breeding season. © Mia Vehkaoja

The Mallard (Anas platyrhynchos) favors beaver-created wetlands, especially during breeding season. © Mia Vehkaoja

The beaver’s actions extend wider than just creating suitable wetlands for several species. Beaver-created wetlands produce high amounts of dead wood. Dead wood is a decreasing natural source and the species dependent on dead wood are under threat. There are numerous bryophyte, lichen and beetle species that rely on moist dead wood. The resilience of beaver-created wetlands is more general than specified, as its transformability reaches from wetlands into the forest.

Beavers provide also other ecosystem services to humans. They mitigate flood peaks by retaining rainwater and drought conditions by slowly releasing water. Beaver-created wetlands act as buffer zones by filtering impurities, e.g. heavy metals, thus increasing water quality. They facilitate and conserve endangered and declined species, and create interesting hiking and relaxation possibilities for humans. All in all, beaver-created wetlands are one of the key ecosystems in boreal areas to be conserved.

Beavers of Finland

We have written some posts about beaver ponds, but in past months I have realized that most people don’t even know that e.g. Finland has beavers at all, and in particular that Finland has two beaver species: the Eurasian beaver (Castor fiber) and the North American beaver (Castor canadensis). Both species came close to extinction in their native habitats during the 19th century due to overexploitation. In Finland the native Eurasian beaver was hunted to extinction in 1868. In 1935 Finland reintroduced 17 individuals of the Eurasian beaver (9 males and 8 females) and in 1937 seven individuals of the North American beaver from New York (3 males and 4 females). Back in those days it was not known that the Castor-genus has two separate species. As recently as 1973 it was discovered that these two beaver species differ in chromosome numbers (C. fiber = 48, C. canadensis = 40). Compared to humans and chimpanzees, which differ in chromosome number by two chromosomes, the difference between the two beaver species is remarkable.

The North American beaver (Castor canadensis) in Finland. © Sari Holopainen

The North American beaver (Castor canadensis) in Finland. © Sari Holopainen

As a result of this duplicate reintroduction, Finland nowadays has approximately 10 000 North American beavers and just 2 000 Eurasian beavers. Why the North American beaver has excluded the Eurasian beaver is not quite clear. The construction activities and body size of both species are similar, but the North American beaver reproduce somewhat more effectively with bigger litter sizes (C. fiber ≈ 2.5, C. canadensis ≈ 4.5). As no other differences have been detected, this higher fertility seems to be the North American beaver’s advantage.

Finland was one of the few countries introducing the North American beaver to its nature. However as a consequence of being introduced to Finland, the North American beaver has also spread out to Russia. As the North American beaver is not a native species in Finland’s or Russia, it is classified an alien species, and is included in Finland’s alien species strategy. The status of the North American beaver as an alien species is quite tricky. Although it has excluded Finland’s native beaver species for the most part, it benefits rather many other native species, such as the common teal (Anas crecca), the moor frog (Rana arvalis) and the Daubenton’s bat (Myotis daubentonii). If we eradicate the North American beaver from Finland, will the Eurasian beaver spread out to the location where the North American beaver has occurred? We can’t know this for sure, but are we willing to take the chance and place the other species benefitting from beaver at risk? One possibility could be that the spread of the Eurasian beaver would be aided by humans. Originally the Eurasian beaver inhabited the entire country, so it has every prerequisite to be distributed to its original range. What strategies Finland’s policy-makers decide to take remains to be seen.

To read more about the eradication plans and shared history of beaver species in Finland and Russia

Parker, H., Nummi, P., Hartman, G. & Rosell, F. 2012. Should (and can) the invasive North American beaver Castor canadensis be eradicated from Eurasia? — Wildlife Biology 18: 354–365.

Or in Finnish
Vehkaoja, M., Nummi, P., Parker, H., Hartman, G. & Rosell, F. 2013. Amerikanmajava Castor canadensis Suomessa ja Euroopassa: pohdintoja vaikutuksista ja mahdollisesta hävittämisestä. – Suomen Riista 59: 52–61.