Beaver ponds and their benefits to wildlife
Beavers have a great ability to influence their immediate environment to utilise resources. Most notably, is their action of dam building. They do this to raise the water levels for several reasons. Primarily, this affords them security in which to forage, cache food under water for the winter and, occasionally to increase protection around a place of shelter ( lodge).
Many other species benefit directly from this activity. Beaver ponds become habitat for many other species, too numerous to mention here. For example, the wetlands are a haven for wildfowl and amphibians, mammals such as water vole and otter, invertebrates and fish, as well as a host of plants and trees such as alder and willow. Below is a selection of species found to benefit from beaver activity in a recent study of beavers in Scotland.
Beavers often dig canals to reach new foraging areas. These canals are used as corridors for safety, as well as to transport feeding and branch materials back to the main dwelling and feeding areas. The canals and surrounding wetland habitats are ideal habitat for water voles – one of our most endangered mammal species.
Hole nesting species such as redstarts ( pictured below ), pied and spotted flycatcher, tree creeper, tits and tawny owl benefit from nesting habitat created from waterlogged trees, which often rot and create nesting habitat which is usually in critically short supply.
Beaver wetlands are a haven for amphibians such as toads ( pictured below ) frogs and newts. The creation of such habitat is of critical importance, as amphibian species are in steep decline, both nationally and worldwide.
Wildfowl in particular benefit from beaver ponds. Many duck species, together with rare species such as water rail and moorhen – two of our most rapidly declining water species, find feeding and nesting habitat in beaver wetlands.
This golden ringed dragonfly emerging from its nymphal skin is just one of thousands of invertebrate species which benefit from beaver wetlands in one way or another.
The puss moth and caterpillar pictured is just one of many species of moth which benefits from beaver impact upon riparian tree species. As species such as willow and aspen are selectively cut, the rigorous regeneration from the stumps attract many invertebrate species such as the puss moth. In the case of aspen – a favoured tree species of beaver, several of our most endangered invertebrate species benefit in one way or another from the different growth stages of post beaver felled aspen. The endangered dark -bordered beauty moth requires aspen saplings about 2-3 feet high. As the trees grow, they become suitable for the rare poplar long horned beetle which requires trees of slender girth and thin bark. While old mature aspen which may be occasionally be felled or even drowned out by flooding are taken over by various hover fly and fly species – some so rare they have only recently been discovered by science. It is thought that these species were once an integral component of beaver habitats.
The vast array of wildlife species which thrive in the ecosystems created by beaver wetlands attract some of our most enigmatic mammal predators such as pine marten and otter. Indeed otters routinely take shelter and breed in old beaver burrows and benefit greatly from the increased fish and amphibian productivity associated with beaver ponds.
So efficient are beaver dams at retaining sediment, that beaver wetlands eventually silt over and become “beaver meadows”. Such meadows are virtual oasis of wildflower meadows. The rich mineral deposits associated with beaver meadows offer optimal foraging for deer and other species. Eventually the meadows are encroached by alder, willow and ash. This woodland type is arguably the most ecologically rich woodland type available. In particular, they offer critically rare habitat for hole nesting bird species, bats and invertebrates.
All images and text copyright © Alan Ross