Beaver creates early successional hotspots for water beetles

Beavers (Castor spp.) are ecosystem engineers that induce local disturbance and ecological succession, which turns terrestrial into aquatic ecosystems and creates habitat heterogeneity in a landscape. Beavers have been proposed as a tool for biodiversity conservation and ecosystem restoration. So far, most research has compared biodiversity in beaver wetlands and non-beaver wetlands, but few studies have explored how beaver-created succession affects specific taxa. In this study, we investigated how water beetles responded to different successional stages of wetlands in a beaver-disturbed landscape at Evo in southern Finland. We sampled water beetles with 1-L activity traps in 20 ponds, including: 5 new beaver ponds, 5 old beaver ponds, 5 former beaver ponds, and 5 never engineered ponds. We found that beaver wetlands had higher species richness and abundance than non-beaver wetlands, and that new beaver wetlands could support higher species richness (321%) and abundance (671%) of water beetles compared to old beaver wetlands. We think that higher water beetle diversity in new beaver ponds has resulted from habitat amelioration (available lentic water, shallow shores, aquatic vegetation, and low fish abundance) and food source enhancement (an increase of both dead and live prey) created by beaver dams and floods. We conclude that using beavers as a tool, or imitating their way of flooding, can be beneficial in wetland restoration if beaver population densities are monitored to ensure the availability of newly colonizable sites.

So its true, there’s more stuff to eat in a beaver pond which is good news for beetles, but there are more things that eat THEM in a beaver pond, because as the fox observed in the little prince, “Nothing is perfect”.

But what about benefits of the non-beetle variety? I mean it can’t all be about the beetles right?

Get Wild: Beavers are the answer

In Summit County, beavers are neighbors to ranchers and urban dwellers, and in both cases, their reputation has not fared well. They flood fields and roads with their dams and find ornamental trees in town irresistibly yummy.

They’re called nuisance beavers, but things are changing.

Biologists have long documented how beaver ponds enrich the ecological habitat for innumerable species of plants and animals, and as people realize the toll of global extinctions and the grave loss of biodiversity, a different descriptor for beavers is gaining traction: keystone species.

More recently, large-scale studies using satellite imagery have shown that beavers significantly mitigate the devastation of wildfires. For example, extensive analysis by ecohydrologist Emily Fairfax of wildfires in five western states, including Colorado, showed that beaver presence reduced the fire damage overall by threefold compared with damage near streams lacking beavers.

Okay. Got that? The nuisance beaver you all complain about can bring biodiversity, rescues animal and plant species and keep your area from burning to a crisp. Does that merit not being killed? I ask you?

The reasons are well known: Beaver ponds feed groundwater, which allows plants to withstand drought and wildfire better. And it doesn’t end with plants. Beaver ponds provide refugia — places where organisms can survive unfavorable conditions — for animals imperiled by fire or other existential threats. Given the explosive increase of wildfires in the West, these results are perking up ears at public agencies.

Well sure beavers can save species and prevent floods but can they do anything else? Are they some kind of Johnny one-note that can only help biodiversity and fires?

And the benefits of beavers aren’t limited to drought areas.

In the upper Midwest, drought is not the problem but rather increased precipitation in the form of more frequent megastorms with consequent flooding of cities like Milwaukee. Data shows that upstream beaver dams could reduce the flooding by about 40% by buffering the water flow and reduce the economic cost of flood damage much, much more (beavers

Thus, beavers help us with both drought and deluge! As one observer has said, “Beavers are the answer. The question is irrelevant.”

Oh okay. Those show-off beavers can prevent floods too. Big whoop. So what if they can increase biodiversity, recharge groundwater, stop fires, remove toxins and prevent floods.

Can they cure cancer? Sniff. I didn’t think so.

You know how it is. You work all year throwing a beaver festival and a week later its all gone. Like the faded shadow of a dream of a dream. Who remembers what they were doing last Saturday morning before the sun came up? Not me.

Never me.

It’s okay though because through our steady effort we moved the needles on public opinion to make this headline possible. Prepare to be shocked. Nobody but us would expect a headline like this. And yes I think the festival had a spiritual, zeitgeist-y, atmospheric role in its subject matter, Why do you ask?

Beavers engineer their ecosystems in a way that helps moose and otters

A whole host of different mammals appear to benefit from having beavers in the area. In forests where beavers have been introduced in Finland, their presence is linked to increased activity of several species, including moose, otters, and weasels.

Beavers are described as “ecosystem engineers” because their dam-building work has such a huge effect on habitats. Both the Eurasian beaver and the American beaver were almost driven extinct by hunting in the early 20th century, but they have since recovered in North America.

Beavers and weasels! Who knew? The glowing article has the very FINEST beaver photo I have ever seen. And I consider myself somewhat of a connoisseur of these things. I bet you’ll agree with me that this photo, from Troy Harrison at the Getty is OUTSTANDING. Teeth, tail, whole package!

More recently, beavers have begun to re-establish themselves in Europe, thanks in part to at least 157 reintroduction projects that have taken place in 24 European countries. The touted benefits they bring to the environment include drought prevention, carbon sequestration, flood management and keeping streams cool.

They are also thought to boost biodiversity. To learn more about their impact on other mammals, Petri Nummi at the University of Helsinki, Finland, and colleagues set up camera traps and surveyed snow tracks at forest sites in southern Finland where the American beaver was introduced in the 1950s.

Moose, red foxes and raccoon dogs visited beaver ponds more than control ponds where beavers were not present. Snow tracks showed that moose, otters, weasels and pine martens were more active in beaver patches than other sites.

Well of course there were. Sheesh. Have you folks just started paying attention? Invertebrates=fish=things that eat fish=things that hunt things that eat fish. And nutrients for the moose! All this means more footprints,

“The otter is a species of some concern in Europe, so this may be important from that point of view,” says Nummi.

Beavers change the environments they occupy in several ways. Their dams flood large areas, creating shallow ponds that harbour lots of invertebrates. The trees they fell create open spaces in the forest where young saplings can grow. When beavers leave a pond and their dams break, the previously flooded area is rich in nutrients and can become a meadow.

Felled trees, saplings and aquatic plants can all provide food for moose. Weasels and pine martens feed on smaller mammals, which may benefit from dead trees they can shelter under. Red foxes and raccoon dogs eat frogs, which are plentiful in beaver ponds. Besides feasting on frogs and fish in the ponds, otters make use of abandoned beaver lodges and ice holes during the winter.

Previous studies in the same area have found that beavers are associated with a greater abundance of bats, frogs and waterbirds.

Nummi’s article has been accepted for publication in New Scientist and we look forward to reading the entire thing some time in the very near future. I’ve included the abstract below. It’s fun reading this as if it was “News”. The Daily Mail picked up the story this morning and is having a party with it. Good. Keep on touting beaver benefits in Europe.

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Abstract

Beavers are ecosystem engineers which are capable to facilitate many groups of organisms. However, their facilitation of mammals has been little studied. We applied two methods, camera trapping and snow track survey to investigate the facilitation of a mammalian community by the ecosystem engineering of the American beaver (Castor canadensis) in a boreal setting. We found that both mammalian species richness (83% increase) and occurrence (12% increase) were significantly higher in beaver patches than in the controls. Of individual species, the moose (Alces alces) used beaver patches more during both the ice-free season and winter. The Eurasian otter (Lutra lutra), the pine marten (Martes martes) and the least weasel (Mustela nivalis) made more use of beaver sites during the winter. Our study highlights the role of ecosystem engineers in promoting species richness and abundance, especially in areas of relatively low productivity. Wetlands and their species have been in drastic decline during the past century, and promoting facilitative ecosystem engineering by beaver is feasible in habitat conservation or restoration. Beaver engineering may be especially valuable in landscapes artificially deficient in wetlands.

Great work. Maybe the American biologists will eventually catch on?