Beavers facilitate Teals at different scales

Wetland ecology group_University of Helsinki_Teal

Teal broods utilize beaver ponds.

Blog text by Petri Nummi, Eeva-Maria Suontakanen, Sari Holopainen and Veli-Matti Väänänen “Beavers facilitate Teals at different scales” is now available on the Ibis website.


Wolf population management – problems in every direction

The wolf is currently quite the hot potato in Finland. In fact, wolves are such a burning topic, that finding neutral information on the current state of the species and on hunting it can be difficult.

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Wolf pup in Polar Park, Norway. © Sari Holopainen

Wolves form packs of several individuals to optimize their ability to hunt moose and deer, their staple food. A pack is run by an alpha pair, or a male and female wolf that have mated for life. The other individuals in a pack do not produce offspring, and young individuals may wander between packs to find mates or raise their position in the hierarchy. Alpha pairs are what keep a pack together.

The wolf is designated an endangered (EN) species in Finland, and strictly protected in the European Union (EU). The Finnish wolf population grew during the early 2000s, due to increased protection and additional individuals moving in from Russia. This increased both the incidence of damage caused by wolves (e.g. to hunting dogs) and the number of wolf sightings around human habitation, leading to dissatisfaction in wolf conservation measures and increased poaching. The wolf population began declining in 2007 due to widespread poaching, which in turn angered conservation organizations and the EU. Since then the wolf population size has seesawed back and forth, and confrontations between various interest groups have escalated.

To alleviate the wolf conflict, the Finnish Ministry of Agriculture and Forestry decided to implement a two-year trial wolf hunt in 2015–2016, aimed to control the population. The effects of the cull will be evaluated after this period. The trial cull is based on a wolf management plan, which attempts to incorporate both the requirements of people living in wolf territory and that of wolf conservation. The management plan is territory-based, meaning all actions are planned per wolf pack and territory.

The management plan determines the smallest viable wolf population as 25 breeding pairs. The Natural Resources Institute Finland (Luke) will produce an estimate for the country’s total wolf population, and based on this evaluation the Ministry determines the largest yearly quota that can be culled using population control permits. However, this quota does not automatically have to be reached.

Population control permits are granted for hunting young individuals, which most likely have the smallest impact on the vitality of a pack. These permits can also be granted for hunting problematic individuals that e.g. repeatedly enter yards or come close to humans. Population control permits can only be granted to target wolf packs that produce litters, or in special conditions on packs in areas where the species has a stronghold. In addition to population control permits, wolves can also be hunted with special permits granted for damage control or by law enforcement. These two permit types are granted only when dealing with problem wolves.

Wolf population fluctuations and management will continue to cause problems in the future. Various interest groups have lost trust in each other and in the Ministry’s wolf management plan. Accommodating both the protection and management of an extremely endangered top predator is very difficult in a situation where said species also causes damage to and fear in certain interest groups. Additionally, protecting the Finnish forest reindeer (Rangifer tarandus fennicus), another extremely endangered species, requires straightforward action plans in terms of the wolf. Population levels of the Finnish forest reindeer are believed to have suffered because of the dense wolf population in the district of Kainuu.

Wetland ecology group_University of Helsinki_wolf_hunting_management

Wolf in Polar Park, Norway. © Sari Holopainen

The complete protection of the wolf, a management regime in practice at the beginning of the 2000s, obviously failed to work. The population grew initially, but was quickly bulldozed by unsustainable poaching. The population decreased up to 15% a year between 2006 and 2010. The population was approximately 250–270 individuals at the end of 2006, but by the end of 2007 the level had dropped to 200. Complete protection of the species crossed a line in Finnish society, after which poaching was used as an excuse for preventing future damage – a situation that should not be allowed to form. Returning to a similar conservation model would require intensive intervention to stop poaching.

The two-year trial cull was completed at the end of February. Luke evaluated the Finnish wolf population at 220–245 individuals prior to the trial period in 2015. Two hunting seasons later, in March 2016, population levels were estimated at 200–235 individuals. When looking solely at these numbers, the cull has managed to keep the population fairly level. However, 43 wolves were shot during the two-year cull, and over half of these (24) were over two-year-old individuals. It is easy to see that the cull has not met its goal of only targeting young individuals. In fact, a staggering 21% of the culled individuals were alphas. And this level may still increase once age determination is complete for all the culled individuals. Such a high number is unsustainable in terms of future hunting management.

Culling each of these alphas has either caused the weakening or disbanding of a pack, leading to higher numbers of individuals or small groups of wolves roaming around unable to optimize their hunting. This is exactly the way to create more problem wolves that willingly come close to human habitation or begin killing hunting dogs. Additionally, several worrying cases have surfaced, where wolves have intentionally been driven towards habitation or have been deliberately wounded to gain more population control or damage control permits for hunting these “problem individuals”. The goal of the wolf management plan is to uphold a viable population in Finland, but at this current rate, the trial wolf cull also appears to have failed.

What next? The future of the wolf cull will be determined during the fall of 2016. The wolf is obviously a species that causes so many societal conflicts, errors in management, and people taking the law into their own hands, that we need to question whether the wolf should remain a species that can be hunted by the general public. Nevertheless, the wolf population does need both management and protection in the future. Perhaps Finland should consider a model where wolf hunting is carried out solely by the (game) authorities. The population control process could remain the same as before, which would allow the cull of problematic individuals and the regulation of pack sizes. But the professional skills of the proper authorities would ensure that overreactions and the killing of alpha individuals could be prevented, which in the long-term could help stabilize the whole population and mitigate wolf-human conflicts.

The beaver is back in town!

The beaver (Castor sp.) is an ecosystem engineer of wetland habitats. Its actions modify both aquatic and terrestrial areas, and several species (e.g. waders, ducks, frogs) are aided by these changes. Beavers are therefore keystone species, and not only do they increase biodiversity through their actions, but can also positively influence humans e.g. mitigating the effects of flooding and drought and by improving water quality. In fact, beavers have such strong effects on their habitats, that their absence from an area where they would naturally occur can actually mean that the area is in a non-natural state and its ecosystem functioning may be (severely) modified.

© Sari Holopainen

© Sari Holopainen

This may well be the case in Britain, where Eurasian beavers (Castor fiber) were hunted to extinction 400 years ago. Some hope maybe on the way though; last week saw the publication of a final report by the Scottish Wildlife Trust and Royal Zoological Society of Scotland, following a licensed release of beavers into Argyll, Scotland. The program, nicknamed the Scottish Beaver Trial (SBT), has looked into the biological, social, and economic effects this release has and will have on Scotland, and results seem promising.

Four beaver families (a total of 17 individuals) were reintroduced to Argyll in 2009, following a long round of discussions and debates that began in the 1990s. Opposers of the Trial voiced concerns of the possible negative impacts the species may cause, e.g. by flooding land and killing trees. The first license application was rejected, and only after the second application did the Scottish Government grant the SBT the right to execute a trial release, in fact the first reintroduction of a mammalian species in the UK to ever take place. The four beaver families were brought into the country in 2008, and after a six-month quarantine period were released into three separate Argyll lakes. The release area is mainly owned by the Forestry Commission Scotland (FCS), and it is also a working forest. This means that the beavers’ actions and impacts on forestry and forest management areas could be monitored. For this same reason the area already had an extensive road and path network that could be effectively utilized in beaver eco-tourism, an aspect that significantly helped to promote the program to the public and local residents. Parts of the area were already designated Special Areas of Conservation (SAC) or Special Protection Areas (SPA) because of their native flora and fauna, and thus visitor facilities were available. Viewing platforms and floating pontoon walkways were constructed to maximize ease of access.

The source population was chosen from Norway, as Scandinavian beavers were concluded to morphologically most closely resemble their UK cousins, based on samples taken from fossil beaver skulls found in Britain. The IUCN has set a strict protocol for species reintroductions and translocations, necessitating the use of the taxonomically closest population as the source.

After release the beavers were monitored by staff using e.g. radio-tracking, visual sightings, and annual health checks, and most individuals seemed to quickly adapt to their new surroundings. Post-release the separate families have accomplished some impressive feats: in total they have created 13 000 m2 of new freshwater habitat (the equivalent of 10 Olympic swimming pools), and constructed several dams (the largest being 25 m in length) and lodges (the largest nearly the same size of a double garage, 7.7×2.1×11.3 m). Despite the radio-tracking, several released beavers and their wild-born offspring disappeared. Five were later found dead, one was caught outside the relocation area and brought back, but a few were never found and were presumed to have moved outside the FCS area.

The first successful reproduction was recorder in the spring of 2010, with a single kit born to two separate beaver families, and breeding occurred during each year of the SBT.

The Trial included monitoring programs for several species, groups, and habitats, to assess how the beavers influenced their populations and ecology, e.g. woodland vegetation and river habitat assessments, mammal (mink and otter), aquatic macrophyte, and dragonfly and damselfly surveys. The socio-economic effects of the SBT were also assessed. The first visual sign of beaver presence was tree-felling, followed by the building of canals, burrows, lodges, and dams. Dam building was closely monitored, so as to ensure that water levels in the SAC areas did not rise to detrimental levels for organisms protected in the areas. When such situations occurred, the dams were either removed or a device was installed to manage the water flow.

The Trial has been a huge endeavor, resulting in the publication of 24 independent journal articles and conference proceedings, and engaging 23 colleges and universities in addition to the three organizations in charge of the program. Volunteering has been enabled from the onset, and has also produced valuable information concerning the beavers’ actions and movement. An estimated nearly three million people were somehow engaged during the trial, ranging from school visits, education programs, guided walks to BBC’s Springwatch that aired several episodes on the Trial. Residents of the relocation area were involved in program planning well ahead of its onset, and planning was made as transparent as possible. The public (including residents) were again consulted at the end of the trial period. The trial also worked with local businesses to develop a ‘beaver brand’ to encourage nature-based tourism in the area. Over the course of the program, the trial won several awards for enhancing local tourism.

The active engagement of both local residents and entrepreneurs and the general Scottish public led to very positive attitudes towards the relocation and the possible future of beavers in Scotland. An estimated 74% of adult Scots favor beaver reintroductions, and 84% of local residents support wild beavers in their area. Such levels can be considered a major success, as the Trial did after all bring in a species that the British have never seen on their home turf, and additionally a species that causes a lot of changes in its living environment, some of which can be potentially problematic and destructive. The SBT succeeded in dispelling fears of the beaver causing socio-economic and/or ecological problems, and showed that local communities can in fact benefit from their reintroduction.

The Trial serves as an excellent example of how relocations should be handled so as to ensure success. Now it is up to the Scottish Government to decide on the beaver’s future in Britain – hopefully a bright one at that. Until a decision is made, the beavers will remain in Argyll. With luck the population will be aloud to stay and more reintroductions elsewhere in the country are on the way.

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Reintroduction of extinct keystone species – which ecosystems should we restore?

Extinctions are a natural part of species history, but for example habitat fragmentation, habitat loss, alien species, hunting and competition with humans have accelerated the rate of extinctions. The extinction of some species is more crucial than that of others, because it may jolt the whole food web or ecosystem. In some cases the whole ecosystem has been maintained by an animal, the keystone species. Without reintroducing the keystone species the ecosystem’s structure and stability might not re-evolve at all or the ecosystem is not complete and self-managing.

How long is too long?

Quite often the main question when talking about restoration is which ecosystems should be restored. Ecosystems have fluctuated through time and so the target is not stationary. Replacing a current ecosystem may not result in the same pure historical ecosystem, but in a mixture from current and historic. Some researchers think that restoration should be aimed at ecosystems existing just after the last ice age before the extinction of big mammals. This was the time before humans greatly effected speciescompositions. With this base, some researchers have proposed the reintroduction of megafauna in the prairies of North America. Megafauna were lost about 13 000 years ago, but some have remained in Africa. Large carnivores and herbivores could work as keystone species and create rare temperate grasslands.

The question is what happens to the current fauna if the old fauna is restored, i.e. what is the value of these actions for the current fauna? In the USA a large share of current fauna is threatened and wildlife is fragmented. Megafauna would need large areas and even current environments are fragmented. Quite many African megafauna species are also endangered and every individual is needed for making the gene pool bigger. In this case restoration would be controversial, because there is a threat that the current African fauna will suffer because of shrinking gene pools and the current American fauna would suffer when losing space.

Megafauna was extinct from North America about 13 000 years ago due to humans. In Africa they survived.  African elephant in Basel zoo. © Sari Holopainen

Megafauna was extinct from North America long ago due to human actions. In Africa they survived. African elephant in Basel zoo. © Sari Holopainen

Good bad wolves

Top predators can be keystone species, but many areas are lacking them because hunting and persecution have driven them to local extinctions. Top carnivores have an important impact in controlling herbivore populations and as a result also vegetation. For example the wolf (Canis lupus) is a keystone species that was killed to extinction from Scotland almost three hundred years ago. There is now an attempt of woodland restoration in Scotland and it has been supposed that also wolves could be reintroduced. Woodlands are not regenerated in Scotland, because of strong herbivore pressure, mainly by sheep and red deer (Cervus elephus). The reintroduction of wolves could decrease deer populations in a natural way and allow forest regeneration.

Apart from ecological aspects, there are sociological aspects that must be considered before reintroductions. In the Scottish example, economic aspects associate with sociological aspects via costs to the sheep farmers. A study about public attitudes against wolf reintroductions revealed that the rural population was concerned about loss of livestock, but still had less negative views to the wolf reintroductions that was expected. Rural population saw deer control as a major benefit brought by wolf reintroductions. Farmers actually had less negative attitudes than the organizations representing them; this might be due to the low price of sheep. But tolerance might not depend on economic costs, and so also emotional consequences should be regarded. The urban population was more concerned about the harm wolves could cause to humans, but they also saw that tourism would be the major benefit. As a conclusion, the general attitude of the Scottish public had a positive idea of reintroducing wolves.

American beaver full fills the ecofunction of the extinct european beaver © Sari Holopainen

American beaver full fills the ecofunction of the extinct european beaver © Sari Holopainen

Restoration of ecofunction

The quality and number of wetlands is decreasing in all of Europe. One of the reasons is that beavers have been extinct from some parts of Europe for a long time and this has had a remarkable effect on wetland availability. In the Kabetogama peninsula of North America the recovery of beaver populations caused strikingly large changes in the landscape by flooding. It can be supposed than also in Europe the effect of beavers has historically been larger. Beavers have been reintroduced in some areas and in many cases they have been successful.

If species have only become extinct locally and remained elsewhere, the knowledge about population biology is available. Genetic evidence must be used reintroducing species, to ensure that the species is the same as the extinct one. This is critical, because usually the target of reintroductions is to restore the original ecosystem. Before advanced gene technology some mistakes were made. For example, in Finland the locally extinct European beaver (Castor fiber) was partly replaced with the American beaver (Castor canadensis). But sometimes the problem is to decide whether a genetic or functional relationship is more important, especially if the original species is extinct. This can concern especially keystone species, because the functioning of a keystone species is in the main role. The target of restoration might be to return the ecofunction instead of the actual original species. Ecofunction was returned although the species was changed with the case of beavers in Finland.

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.

Beaver floods as waterbird kindergartens

Boreal forest lakes are usually barren; vegetation is scarce and shores are deep. For ducklings and wader chicks these lakes offer food poorly. Luckily there are beavers, which by damming streams and ponds create good foraging and nursery habitats for breeding waterbirds. Damming allows water flood into the forest, increasing invertebrate production. Mosquitoes and other small emerging insects colonize new ponds and are food for ducklings and chicks. Shallow water guarantees that even small ducklings can reach the bottom when looking for food and in addition the rich vegetation offers cover from land, air and water predators.

Beaver ponds offer shallow foraging habitats for ducklings © Sari Holopainen

Beaver ponds offer shallow foraging habitats for ducklings © Sari Holopainen

In our recently published study from Finnish boreal lakes, the beaver effect was measured at the waterbird community level. From the waterbird perspective, beaver disturbance seemed intermediate in intensity, which led not only to increased numbers of waterbird species but also to a higher abundance. The facilitation led to a higher abundance in the group of seven studied waterbird species: all seemed to benefit from beaver at least to some extent. The common teal (Anas crecca) and green sandpiper (Tringa ochropus) showed numerically the most positive response to beaver flooding. These species could be seen as disturbance species, which readily colonize newly formed flowages.

Beaver, the ecosystem engineer © Sari Holopainen

Beaver, the ecosystem engineer © Sari Holopainen

The beaver acted as a whole-community facilitator for waterbirds by modifying the habitat to a more favorable state. This has also been seen in other species groups, for instance in frogs and bats. Species richness is limited by stress and resource availability at low productivity areas like boreal lakes, so resource amelioration should increase species richness. The increase of invertebrate food in beaver flowages apparently is the common nominator in the increase seen in all the species of our study. Experimental studies strongly suggest that duck broods are resource limited in boreal lakes. Most of the species certainly also benefitted from a change in habitat structure, i.e. from the increase of shallow water in beaver ponds. The average shore depth (0.5 m from the shoreline) of the beaver ponds in our study area is less than 25 cm, which provides the waders as well as duck broods with a clearly more suitable foraging habitat than that of over 60 cm in undisturbed lakes.