Beaver Library

For thousands of years, beavers had a big influence on the Dutch ecosystem and the people that lived there. This is the conclusion of research by archaeologist Nathalie Brusgaard. The rodents were used for food, clothing and tools, and created a landscape hospitable to many other species.

Ecosystem engineers, such as the Eurasian beaver, Castor fiber, transform habitats, thereby creating favourable conditions for other species and increasing biodiversity. Multiple studies have revealed that beaver ponds are valuable habitats for invertebrates and vertebrates, including other mammals, but the impact of watercourse damming on the fauna of small terrestrial rodents and shrews has not yet been documented. We aimed at testing the hypothesis that the presence of beaver dams and consequent flooding enriches the small mammal assemblage both quantitatively and qualitatively. We live-trapped small mammals at nine beaver-modified sites on 300 metre transects alongside dammed watercourses, starting from the dam through to the pond to the sections with unmodified lotic conditions. The abundance and species richness of trapped small mammals were highest near the dams and declined with distance. Additionally, five out of 12 trapped species significantly decreased their abundance with distance from the dam and none revealed the opposite trend. Four species were more abundant on plots subjected to damming (especially Sorex minutus and Micromys minutus), while none were present solely on undammed plots. Among the semi-aquatic species, two water shrews benefited from beavers’ activity in different ways. Neomys milleri occurred only in flooded sections, while N. fodiens preferred unmodified sections, but was the most numerous closer to the dams, following the already known patterns of competitive displacement observed in Central Europe. An important factor affecting small mammals, the herbaceous layer cover, appeared to be interdependent with damming. We provide the first unequivocal evidence that beaver dams facilitate the abundance and diversity of small mammals, presumably due to increased food abundance, availability of shelters and habitat connectivity. Beaver-created wetlands may act as potential refuges for the species most susceptible to the consequences of anthropogenic climate change, while revealing a critically low range-shift capacity.

Ecosystem engineering species, such as beavers, may help the restoration of biodiversity. Through the building of dams and lodges and altering the natural hydrology, beavers change the habitat structure and create multiple habitats that facilitate a wide variety of other organisms including terrestrial invertebrate communities. Here we study the effect of beaver reintroduction in Klosterheden in Denmark on biomass of flying invertebrates and diversity of moths. Further, aerial photos were used to assess riparian structure and productivity using the normalized difference vegetation index (NDVI). Our findings show that the presence of beavers affected flying invertebrate biomass, but that this was dependent on time of the year. Further, a strong effect of presence of beavers was found on diversity of moths. The results also show an increase in vegetation productivity and structural heterogeneity at sites with presence of beavers. Overall, our results demonstrate the importance of beavers as important ecosystem engineers that affect invertebrate species composition and abundance, as well as riparian structure and productivity.

Beaver are ecosystem engineers capable of converting free-flowing lotic habitats into a series of lentic ponds, thereby enhancing the wetland area of a riverscape. Process-based riverscape restoration using beaver reintroductions and mimicry (beaver dam analogues, BDAs) are increasingly used to restore  functions, the provisioning of services, and improve the resiliency of ecosystems across North America and Europe. Beaver can create breeding habitat for a wide range of species within the highly imperilled class Amphibia by increasing wetland area, increasing emergent vegetation, prolonging wetland hydroperiod, and creating deep ponds.

Biodiversity is declining in the UK, which is considered one of the most nature depleted parts of the world. The reestablishment of the Eurasian beaver (Castor fiber) has been posited as an effective means of facilitating a restoration of biodiversity in Britain, and following successful trials, nationwide reintroduction is being considered. This literature review considers the potential psychological benefits of such an initiative. Beavers could act as a ‘super restorer’, facilitating psychological as well as ecological restoration through a beneficial synergy of effects. Through their eco-engineering activities, beavers increase biodiversity at the landscape scale and facilitate habitat restoration and creation (creating a mosaic of green and blue space, and a sense of wilderness) all of which can increase the psychological well-being of visitors. Their creation of biodiverse natural settings offers the possibility of increased nature connectedness and nature-based psychological restoration amongst some of the human population of the UK. Beaver reintroduction may represent a partial antidote to ‘shifting baseline syndrome’ and beavers could act as a flagship species and become a totem of hope as eco-anxiety increases. Beavers can potentially have negative psychological impacts, and this will require appropriate planning, management and communication among stakeholders coupled with community-led initiatives to mitigate. Overall psychological benefits of beaver reintroduction likely exceed that of any other single species’ reintroduction or conservation initiative of equivalent cost, and far outweigh the costs of their reintroduction and management.

The engineering activities of the Eurasian beaver Castor fiber have far-reaching effects on the components of an environment and therefore modify the functioning of the ecosystem. The wetlands thereby created are the most conspicuous effect of beaver activity and attract water-related species. However, there is some evidence suggesting that beavers influence not only aquatic ecosystems but also the terrestrial habitats adjacent to these wetlands and the organisms occurring there. Because the impact of beavers on terrestrial birds is still poorly understood, this study evaluates the assemblage of birds wintering on beaver sites (N = 65) and paired reference sites (N = 65) in temperate forests of central Europe. We investigated the correlations between beaver presence, parameters of wetland areas, terrestrial vegetation characteristics, distance from the water’s edge and bird species richness and abundance. We found a greater species richness and abundance of wintering birds on beaver sites than on watercourses unmodified by this ecosystem engineer (by 38% and 61%, respectively). Species richness and abundance were higher in the terrestrial habitats near the edges of beaver ponds, but for some species this tendency also held in forests growing at some distance from beaver wetlands. Greater species richness was related to beaver presence, but also increased with a more open canopy and greater forest floor diversity, whereas bird abundance was correlated only with canopy openness.

In general, rewilding aims to reestablish vital ecological processes that can involve removing troublesome nonnative species and restoring key native species. Our rewilding call is grounded in ecological science and is necessary regardless of changing political winds. Our objective is to follow up on President Biden’s vision to conserve, connect, and restore by identifying a large reserve network in the American West suitable for rewilding two keystone species, the gray wolf (Canis lupus) and the North American beaver (Castor canadensis).

Rivers and streams, when fully connected to their floodplains, are naturally resilient systems that are increasingly part of the conversation on nature-based climate solutions. Reconnecting waterways to their floodplains improves water quality and quantity, supports biodiversity and sensitive species conservation, increases flood, drought and fire resiliency, and bolsters carbon sequestration. But, while the importance of river restoration is clear, beaver-based restoration—for example, strategic coexistence, relocation, and mimicry—remains an underutilized strategy despite ample data demonstrating its efficacy. Climate-driven disturbances are actively pushing streams into increasingly degraded states, and the window of opportunity for restoration will not stay open forever. Therefore, now is the perfect time to apply the science of beaver-based low-tech process-based stream restoration to support building climate resilience across the landscape. Not every stream will be a good candidate for beaver-based restoration, but we have the tools to know which ones are. Let us use them.

For this article, the researchers examined sites with evidence of new beaver pond colonization in the Arctic. Snowmelt is occurring, which is reducing permafrost and creating ideal habitat conditions for beavers. Beaver populations are now in competition with native ptarmigans. Tape et. al. suggest that beaver ranges are expanding rapidly in the Alaskan arctic.

Wetlands are declining worldwide, and there is a great need for their restoration and creation. One natural agent of wetland engineering is beavers. The study was conducted in Finland to address facilitation of waterbird communities by between beaver activity. The article also evaluates how the results of the study have been used in management.

While Britain has had a slower start than some mainland European countries, beaver reintroduction is now gathering traction motivated by prospects of habitat enhancement, natural flood management and wider biodiversity benefits.

To determine whether reintroduced beavers, as an example of native herbivorous megafauna, can increase freshwater biodiversity at the landscape scale and to compare effects on two contrasting taxonomic groups.

A study that suggests a high density of the biological signaling field is a sign of possible depletion of food resources, and can explain how beavers can have such a large range.

This study compared various measures of biodiversity levels of mammals in the winter months between wetlands on agricultural land and wetlands, as well as wetlands with active and inactive beaver colonies.

Dam building by beaver in degraded environments can improve physical and biological diversity
when viewed at a scale encompassing both modified and unmodified habitats.

Research article that used camera trapping and snow track surveying to investigate the facilitation of a mammalian community by the ecosystem engineering of the American beaver in a boreal setting.

Study that finds beaver-induced changes to habitat quality, stability, and connectivity may increase spotted frog population resistance and resilience to seasonal drought, grazing, non-native predators, and climate change.

Short overview of the Great Blue Heron with a brief description of their reliance on beaver.

A review that investigates the mechanisms by which beavers act as ecosystem engineers, and then discusses the possible impacts of beavers on the biodiversity of Scotland.

Study that examines relationships between dam density, riparian area characteristics, and the riparian bird community in a semiarid landscape.