The Beaver and the Bee
Beavers and bees. Not two creatures you’d typically associate with each other. One’s a big, furry mammal, with a funny tail and a fondness for wet places. The other’s a gang of little, furry insects, with six legs and a penchant for wildflowers over water.
It might not seem obvious at first, but this mega mammal and these minibeasts are interlinked. And it’s not just bees. Bringing beavers back also opens the door to a whole diverse mix of invertebrate life.
If you add beavers to an area, it starts off a sort of chain reaction. Knock over your first beaver-shaped domino, and the rest will start toppling into place. It’s well known that beavers are ‘keystone’ species – when they live in an area they don’t half make themselves known! By affecting both tree cover and the way water flows, they cause knock-on effects that benefit lots of other different types of wildlife. So, just how does this benefit insects?
Beneath the surface
One of the first ways a new beaver family will influence their habitat is through the water they swim in. Beavers are amazing dam-builders; they’re pros at blocking a river’s path with their woody structures. If you’ve ever played with rocks in a stream – you’ll notice that behind a dam, the water quickly slows and starts to pool.
Freshwater invertebrates are massively diverse – and different species prefer very different, and very specific conditions to live in. When it comes to water, some like it still – living life in the slow lane. Others prefer the fast life, and need babbling, flowing water to thrive. Types of stonefly, caddisfly and mayfly tend to prefer flowing water – often loving the riffles and bypass channels downstream of a dam – whereas many species of dragonfly, damselfly and molluscs will prefer stiller water, ponds and pools.
Before beavers, a river might be consistently fast-flowing along any given stretch. When a dam arrives, the water behind it slows down, and beaver pools are formed. This can often encourage algae to form, providing the very foundation of all aquatic food chains. These still stretches of water will soon start to host a whole new variety of invertebrates!
Beavers and botany
There are some obvious connections between beavers and plants. They fell trees and gnaw branches for their lodges. Juicy stems, twigs and buds make up their plant-based diet. But once again, there’s a more subtle link between beavers and the world of botany. And it manifests itself in beaver meadows.
When pools form behind dams, the area around them floods. Trees will die, the canopy will be opened up, and nutrient-rich sediment in the water will sink to the bottom as the flow slows down. Inevitably and eventually the beavers will move on. Their abandoned dam will eventually break down, and the river will return to being a slimmer, faster-flowing body once more.
The water from the wider area retreats and the silted bed of the beaver pool is left exposed. Without trees to compete with, these ex-beaver pools can become beaver meadows! The open areas create the perfect conditions for a unique mix of wildflowers and other plants, whose seeds may be buried in the soil. Bees, hoverflies, butterflies, moths – these meadows support a whole range of different insects and pollinators!
There are massive, ghostly forms missing from our landscape. The decline in both standing and fallen deadwood in the UK is well documented; trees dying, and rotting, where they stand have become a rare sight.
Deadwood is a vital habitat for heaps of wildlife. Many species of fungi and invertebrates have evolved to take advantage of a bounty of rotting wood that would naturally exist in an ecosystem. Our tendency to tidy up and remove dead wood means lots of the specialist invertebrates (referred to as saproxylic) are now extremely rare in the UK. Fortunately, beavers once again can lend a helping hand to these struggling species! They help create vital deadwood in two ways.
Firstly, they directly target wood around their dams; felling a few trees for their lodges and leaving their coppiced stumps to regrow in many cases, but also to rot. Secondly, the floods caused by said dams will spread into woodland around a river. Many species of tree can only tolerate infrequent flooding, so as beaver pools form, a few unlucky trees might die off. On the whole though, trees actually like being coppiced, often sending out new shoots and triumphant regrowth!
As tree skeletons are left behind, the rotters can move in! Species of beetles, flies, moths, sawflies and spiders are all known to rely exclusively on rotting wood – so dead trees for them is a good thing!
So, although bees and beavers might not have a lot in common, you can hopefully see how one element of our wildlife can influence another. Invertebrate diversity is vital to a functioning ecosystem. By bringing in the big players like beavers, we can open the door to a greater invertebrate diversity in our landscapes!
Lucy Hodson (aka: @lucy_lapwing) Beaver Believer
Lucy is a conservationist, naturalist and self-described nature nerd. Passionate about connecting wider audiences to our natural world, she is an eco-worrier turned eco-warrior! As well as working for a large conservation charity, Lucy is a science-communicator; blogging on Instagram about wildlife and nature in the UK.
#beavers #beaverbelievers #beavolution
© Lucy Hodson 2020.