Thursday, 20 November 2014

Floods and Dams - Beavers rebuild a breached dam.

This is my piece for December's number of the Alyth Voice. 

Floods and Dams

Rainy, mild November, I walk out of the house, glance around me and set off right, down the drive. Some big yellow leaves of the lime trees still hang, spare and bright against the dark background of damp, dripping trunks: others flutter sodden to the ground.

The pot holes are worse than ever: I must order more of the Type 1 from Collace.
Almost the worst stretch of the drive from the point of view of potholes is the bit under which the main ditch flows. Upstream, the burn has overflowed into the rushy wetland that forms its border. Downstream, the pool is full. The dam that makes this pool must be overflowing. I turn left to walk along the Burnieshed path and note that an apparently abandoned burrow has been reoccupied: fresh mud over the roof and newly laid branches and twigs tell me this is so. I walk on. Water is lipping over the brim of the dam and cascading down a spillway. No self respecting salmon would have a problem surmounting this dam, but then I wouldn't expect salmon here for this is trout water, both brown and sea trout.

I walk along the wetland below the path, crossing the moss and lichen covered trunks of fallen trees, and return to it after looking at an old birch, whose gnawed trunk reveals a great cavity within. This is the tree that bled sap in the summer on being gnawed, and sustained a family of wasps, reminding me that restored species bring with them unsuspected opportunities in the way of habitat and food for others. Regaining the path I walk under a willow, along part of whose overhanging bough a beaver climbed in the summer of 2013. Around me I note the presence of an abundance of Sitka spruce saplings, the offspring of the hundred and fifty year old monster by the burn.

Retracing my steps I join the drive and turn left past the stacks of timber, ready for burning later this winter: Yule logs on an industrial scale. I pass the track that leads through the Tay Bridge Wood, whose name is a reminder of the storm of 28th December 1879. The track, itself, is a mess. Deep ruts, made by heavy forwarders have made bits of it impassable for walkers and light vehicles. Only great machines with huge wheels can travel in and through the plantation, compacting the soil to its scaith. Continuing on my way, I pass some wild boar. They have gathered near a gate and are waiting to be fed. I walk on. The object of my walk is to photograph a new dam down the drive: its building has resulted in the creation of a beautiful pool of limpid water, already colonised by many water beetles. Downstream of the main dam is a smaller one: beavers often build dams in pairs, the lower one adds stability to the upper one by reducing the speed of the current immediately below it. I take a few photographs and, once satisfied, set off back up the drive.

Considering the height of the water at the pool next the drive, which I walked by only a few minutes earlier, there is a remarkable amount of water weed showing. But no, that's not right. The water level has dropped. The dam has breached! In the quarter of an hour or so since I passed it the dam has collapsed. Water is pouring through a gap in the middle of the dam. One hundred yards below, the next dam has been breached too and the water level is dropping to reveal the floor of the pools and burns.

These floors are covered with vegetation: water star wort, water milfoil, pondweed. At the boggy water's edge trails of brooklime tangle with the underlying plants and branched bur reed lies in swathes along the bank. What a diversity: ten times the number of plants there used to be before the beavers came (as I learned from Alan Law's PhD thesis). Meanwhile, the water has cascaded through the gap in the dam and breached the dams below.

 A week later, despite nearly constant rainfall, the dam has mostly been repaired, leaving a narrow channel through which the water races. Today, the 19th November, the beavers have closed this gap. Once this work is finished they will turn their attention to the other dams downstream. No doubt all will be ready in time for Christmas! We shall be able to drink their health in Bibergeil, another of those pleasant herbal liqueurs that the Germans make to keep out the winter chill.

Here is the High Dam before the burst. I think I took this photo sometime in October.

Here is the dam again soon after breaching.

And again

This photograph, taken the next day (8th Nov. or so) shows that the beavers are already rebuilding, despite the fierce onslaught of the water.

We were away from home until the 15th and I took this photo on the 16th. The beavers' work has been heroic, but what about that gap?

Here is the answer. I took a walk along the Burnished path a couple of days ago and was delighted to notice that they had bridged the gap. The beavers have regained control!

I saw a kingfisher just after the bursting of the dam on the 7th November and have been delighted to see dippers a couple of times in the last week. It was the first time I had seen a kingfisher in that burn.

Monday, 22 September 2014

A new flow levelling device at Bamff

As I walked along the ditch to visit the Wet Wood one day in July, or so, I noticed that the beavers had built a fine new dam. I thought little of it because there were no signs that water was seeping up into the field to the south.

Some weeks later, however, I noticed that the dam had grown and that the endrigg of the field to the south (the Ladyswell Field) was flooded. What to do? I must ask Lush (Lewis Smith) to come and build a pond leveller.

Lush was busy for a week or more, but he came last week and inserted this pipe and his trademark tall wire cage to protect the inlet of the levelling pipe.

What will the beavers do next?

And Now Autumn!

Summer is past and not a post since June. It must be time to try and make up for this dereliction.

With the coming of autumn beavers become especially active. More of this later because there is some catching up to do.

On the 14th August a team from the Tay Salmon Fishery's Board, led by Dr. David Summers came to carry out electro-fishing in the Burnieshed Burn. They were accompanied by Drs. Nigel Willby and Alan Law from Stirling University and Sean Dugan from the Freshwater Fisheries' Laboratory at Faskally.

We noticed that wasps were benefitting from the sap exuding from a freshly gnawed birch: evidence of the way in which beavers and other restored species can return a long forgotten dynamic to the environment.

A few of the captured trout in a bucket. About sixty trout were caught. Little trout inhabited the running waters of the burn and some bigger fish lived in the slow moving pools, created by the dams. The biggest trout caught weighed a little over 1kg.

Alan Law and Nigel Willby take a break.

This takes me on a little. Walking to the Wet Wood one day this dragonfly landed on my left hand. I managed to photograph it, but have no idea to which species it belonged. There are small orange patches at the base of the wings.

The crumpled and folded piece of paper below shows the impact of beavers at Bamff since they came here in 2002. Monitoring of the vegetation started in 2003. Between 2003 and 2014 the number of species of plant in the areas where they are active has nearly doubled. Think what this is doing for biodiversity!

Monday, 30 June 2014

New Dams and Bumblebees

One of the new dams down the drive at Bamff.

The Flight of the Bumblebee

High summer: the longest day is past and the first cuts of grass for silage have been taken. I see the lengthening candles, the leading shoots, of the Scots pine giving a golden cast to the distant plantations on the Bamff hill. As I walk about I notice that ribwort plantains are in flower.

Down at the roadside by the Steffort corner there are tall purple flowered comfrey plants. They have attracted bumble bees of several species: the air on a warm day buzzes with them as they forage. I enjoy watching and trying to photograph them. Bumblebees are surprisingly difficult to catch for a shot, as you want them showing their whole body while they, most of the time, are busy sticking their tongues down the flower to get at the nectar within. Their bodies, then, are usually bent and partly invisible to the photographer. A bee checks a flower: no nectar there (that one has been visited by another bee recently); off it goes to the next flower, rejecting others on the way. Often it is possible to photograph the head and thorax, but not the lower part of the abdomen (or the other way round). To the beginner in bee identification the whole body is important because a bumblebee with a white tail may not be a white tailed bumblebee (Bombus lucorum): there are other species with white tails, but differently striped thoraxes. Well, there we go! When you get a good shot of a crisply focussed bumblebee in flight, amid a forest of softly focussed green vegetation, you have won a rich reward.

It was interesting to attend the open day at Rosemount Farm recently. The managers had set up fine, big polytunnels for exhibitors’ stands, so there was shelter from the sudden thunderous showers that soaked folk at the Alyth Gala.

Angus Fruit Growers, had a stand that focussed on the importance of bumblebees for their enterprise. A ventilated box containing buff-tailed bumblebees (Bombus terrestris) was on show. The occupants are released into polytunnels in spring to pollinate the flowers of the strawberry or raspberry plants within. Farming bees for use in growing raspberries and strawberries has become big business. Many of the bees used are imported from Slovakia: like the students who come to pick the fruit, essential immigrants.

Going back to the plantain, I see that research carried out in the Swedish Ă…land Islands, over the last twelve years, has shown that ‘isolated, fragmented ribwort populations were more frequently infected with powdery mildew than were well-connected ribwort populations’(( Fragmentation of habitats makes many diseases worse.

Such fragmentation is manifest everywhere you go. A recent walk along the Seaton Cliffs outside Arbroath reminded me of the fact of fragmentation of habitats in our countryside. A few yards of cliff head with path: beyond that, inland, as intensive arable cultivation and soft fruit growing in polytunnels as you could find anywhere. Beside the path the hogweed buzzed with bees and the air was thick with the cries of the kittiwakes. Were the bumblebees taking time off from the polytunnels to remind themselves of the taste of the nectar from other species, or were they just locals out for a buzz?

The forgoing was my article for July's number of the Alyth Voice.

I came across this link earlier today. It emphasises the dangers of the international trade in bumblebees from the point of view of the spread of disease.

Wednesday, 18 June 2014

18th June 2014

I am delighted with this new dam on the east side of the drive to Bamff House.

And this one a little further down stream.

The Ragged Robin is out now.

Here is some coppice regrowth from young stems cut last winter.

And the iris. Hurray!

It was good news to learn that the RSPB are keen to see the beaver restored to Scotland.

Not before time, I think, for them to come out into the open.

Sunday, 30 March 2014

Yesterday, carried away by the effort to post a blog after so long, I posted another one but put it on the wrong Blog. Here is the link to get to my alternative and previously unused blog.

Saturday, 29 March 2014

Winter 2014

This photograph is taken from the B954 at the junction with the road that goes to Leitfie, looking South. The flood was not at its most extreme because the road was passable, having been under water a few days before.

Winter has more or less passed: April is next week. Here are some photographs to show that I have been up and about a bit.

The beavers in the Wet Wood have been active throughout this mild winter. This photograph shows some scraping of dead vegetation off the ground to an extent that I haven't noticed before. What a seed bed for willows! And, no doubt all sorts of other plant life.

February brings with it the annual visit of the Edinburgh University First Year Ecology class. They have been carrying out a monitoring project for the last three years and come equipped with nets, tapes and sampling equipment.

Sunny March: A view of the Long Dam.

A wander up into the plantation to the south of the Wet Wood revealed that some drains were being cleared by the beavers after many years of neglect.

          • Next we come to the joy of Spring - a profusion of frog spawn.

That is all for now, I think. I have lost my touch with Blogger, so some photos have come out huge and others small. One of two seem to have disappeared altogether. Well, not altogether, I seem to have fixed something.

Ciao for now!