The Long Dam

A roaring kind of Spring has arrived, even if a month late. Snowdrops are still in full blossom and the daffodils are still in bud.

The big dam in the Wet Wood has been extended a bit at its southern end (not to be seen in this photograph).

 Nor does this photo show the extreme southern extension, but is taken from just south of the ditch where the first little plug was built to block it eleven years ago.

I must go out and photograph the southern end and the paths that lead into the plantation.

Wild Boars and Snowscapes of Beaverdom.

Here, just for a change, is a photo of some wild boar.

Back to the Wet Wood at Bamff and the beavers who live there.

This is a dammed area at the west end, where the beavers have dammed water coming from one of the ponds that was dug in the autumn of 2001. A canal leads from the pond in question through to the big expanse of water that the beavers have created with their Long Dam (about 100 metres).

I took this photo with the panoramic facility of my iPhone. It shows the Long Dam I mentioned above and the pond thereby created.

This photo shows the small pond in the middle distance. A ditch dug in the early nineties, or even earlier leads the eye to a trap, not yet set, that is going to catch a beaver for blood sampling as part of the Tayside Beaver Study Group's work of monitoring the beavers of the Tay.

Easter is early this year, but I don't remember a white Easter here, although we do get snow until May sometimes. My first lambing here, in 1981, was made more interesting by heavy snow falls. Luckily, the snow soon melted.

Now, here's a thing. While we were in Oregon in January, attending the State of the Beaver Conference, Paul Henson of the Oregon Wildlife and Fisheries Department spoke about surrogate species. He was keen that the beaver should be seen as a surrogate species. I have pasted in Heidi's Call to Action below, which explains 'surrogate species' as a technical term.

From: Heidi Perryman [mailto:hdshrnkr@comcast.net]Sent: Monday, March 04, 2013 11:18 AMTo: 'beavers@surcp.org'Subject: Recommending Beaver as a Surrogate species - Don't forget!

A Call to Action:

   Posted by heidi08 On March - 4 - 2013

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 << OLE Object: Picture (Device Independent Bitmap) >> After the State of the Beaver Conference, I talked mentioned the mandate for Fish and Wildlife services to focus its efforts on a few key ‘SURROGATE SPECIES‘. State supervisor Paul Henson had recommended we think about beaver in this role, and asked for public comment. Since there are about 25 days left for your comments to be submitted, I thought I would offer some reminders and encouragement.

In case you slept through that biology class lecture, a SURROGATE SPECIES is defined thusly:

A species selected as a priority for conservation with the assumption that its conservation will serve to protect many other species with overlapping habitat requirements.

This is a tool for monitoring ecological systems, although obviously not a perfect tool. Just as following the regional price of cardboard will tell you something about the amount of shipping that occurs in the US, but it won’t tell you everything you need to know about the economy, for example. It has been successfully argued that watching ONE token species often misses important impacts to others.

Case in point, if we were to watch beavers as a surrogate species, we would have a good chance at learning about conditions for salmon and birds and dragonflies – but if there were a specific toxin introduced to the water that killed fish and everything that ate them, we might not find out about it at all from watching beavers. Fair enough. As a tool it has its limits. However, if we routinely destroy beaver dams we can assume that all the species that depend on them will be dramatically impacted, even if the food chain is preserved. So surrogacy has an undeniable value.

There are several types of surrogate species, including

Umbrella Species:

Where the conservation goal is to protect a habitat or community of species, an umbrella species may be employed as a surrogate to delineate the size of area or type of habitat over which protection should occur.

Flagship Species:

Flagship species are used to attract the attention of the public Flagship species can garner sympathy for nature at a global level, as in the case of the giant panda, the emblem for the World Wide Fund for Nature, or at a national level.

Indicator Species:

Defined “an indicator species [as]an organism whose characteristics (e.g., presence or absence, population density, dispersion, reproductive success) are used as an index of attributes too difficult, inconvenient, or expensive to measure for other species or environmental conditions of interest.” This can include Health Indicator Species, Population Indicator species, and Biodiversity Indicator Species.

I would argue that beaver dams and the wetlands they create, (as well as beaver chewing and subsequent coppicing), make them is an excellent candidate for Biodiversity Indicator Species, as well as an Umbrella species, and as it happens, (In Martinez and the entire Bay Area for nearly two years) a powerful Flagship species to boot. The effect of our beavers on our tiny urban stream is still being measured,  and there is reason to think that if every city took care of its beavers, every city would have this and more:

 << OLE Object: Picture (Device Independent Bitmap) >> In addition to creating habitat for these and countless other species, I would add that beavers make an excellent SURROGATE SPECIES because they leave clues that are convenient for burdened agencies to track track down. You don’t have to install night cams or get up at 3 in the morning to keep track of beaver. You just need to count dams and chews whenever you can get around to it and keep your eyes open. Even though they can be hard to see, beavers are actually fairly easy to monitor.

Need a few more reasons? In addition to being a Keystone species, beavers are also considered a Charismatic Species which means that children and adults LOVE to learn about them. They can help teachers convey difficult concepts like habitat and ecosystems, which is why they were included in the EPA curriculum for every first grader in California. Beavers also teach problem solving skills, since their challenges are so easily solvable that it might inspire folks to solve other wildlife problems in humane ways.

Last reason? CLIMATE CHANGE.

With more than half of the contiguous States in the U.S. identified under extreme drought conditions last year, we are should be more protective than ever of our natural water-savers. Drought conditions are recognized by FEMA as a natural disaster, making counties eligible for federal funds to recover crops, cattle and neighborhoods destroyed by dry conditions. Beavers and their remarkable capacity for water-tending,  are one of the only renewable resources we can deploy to successfully combat this ongoing crisis.

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I know you’re busy, and life is full of demands. But 431 people read this website on Friday and you each have the power to make a huge difference in the lives of beavers. Fill out the form, or submit your comments here. And if you do let us know, and we would be thrilled to post all or part of your comments on the website to show what a beaver community is capable of.

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http://www.youtube.com/watch?v=jwXZaeqUBWA

Beavers along the Dean Water where it flows under the A90 near Forfar Loch.

I forget when word reached us that some poplars by the Dean Water, where that stream flows under the A90, were thought to be in danger of being felled onto that road by beavers. 

Nobody seemed to know whose land the trees were on and so no one was sure whose responsibility it was to do something about the trees.

So nobody did anything about the poplars until BEAR decided to fell such trees as might fall over the A90 if felled by the beavers.

As everyone knows the poplar genus is the beaver's favourite.

We approached the place of the poplars by way of the Forfar Loch (where we saw fresh evidence of the presence of beavers: cut willows that will coppice in the spring). This photograph shows the Dean Water as it flows out of the Loch. 

Originally, the Forfar Loch stretched as far as Glamis (only a few miles downstream), but draining for agriculture started, I think, in the seventeenth century. The Dean Water was canalised and deepened to drain the loch. The soils are fertile, but very prone to flooding.

We crossed the A90

and approached the clump of poplars and alders. 

It wasn't long before we saw trees that the beavers had felled.

Most, if not all the trees had been numbered, though why this willow had been treated in this way I do not know.

A Bavarian beaver trap had been set as part of the Tay Beaver Study Group's monitoring programme and a trail camera had been placed by the tree behind it, as you can see in the next photo.

Looking down the Dean Water.

This is one of those charming, forgotten fragments of land that, as it seems, belongs to nobody.

Here you can see signs of beaver burrows. Much of the digging must have been done to escape from flood waters through the winter. There is also a handsome food cache in the water.

These poplars were the ones nearest to the road. You can see a lorry on the sky line. 

It seems to me that all these trees could be protected with rabbit netting fixed round the base of the trunk , pinned down at the bottom and supported by a couple of rebars. 

Roadworks by the Bamff Drive

At last, the decision had to be made to do something about the dam in the distance. 

The beavers had rebuilt it after its breaching at the time of the logging of the Whitehills Plantation this time last year. Then, with all the rain, snow, snow-melt and more rain, they had gone on building up the dam so that the drive was lower than the water level at the dam. All this was continuing after the work of mitigation that we had carried out lower down the dam to protect the lodge at the end of the drive.

Water was increasingly running down the drive.

Lewis Smith (Lush) and his colleague, Terry, were keen to instal pond levellers, but felt that more radical action was necessary. Stewart Crabbe, the top of whose head is missing in the photograph on the right, found that the old stone culvert that drained the Big Pond was dug in very low. It would be necessary to unblock the culvert, in which case the dam below could not be allowed to be rebuilt, or to instal a new pipe under the drive, but lying over the old culvert. I was keen for the dam to be restored as much as would be consistent with a dry drive.

Accordingly, a pump was set to work to drain the pool that you see in the top two photographs and the dam was dismantled with great care to avoid sudden collapse. Next, Stewart Crabbe excavated the channel that leads to what had become the dammed pool.

Then the drive was dug up.

And the new pipe was installed.

Downstream, the dam had been lowered to the bed of the ditch.

Would the beavers return to rebuild, or would they move off?

By Monday we had the answer: the beavers had begun to rebuild their dam. It remains now to decide at what level to instal a flow device. 

I should say that the drop in the level of the water in the channel revealed a burrow, so the beavers will be keen to cover signs of its existence.

Pond Levellers, flood mitigation measures and some dams.

The photographs and map in this post are here to tell the story of some attempts to manage affairs to the convenience of the humans who live here, but not forgetting the well-being of the beavers.

Nearly a year ago the plantation woodlands in the southern part or bottom of the Google photo below were to be felled. The contractor was anxious that his trucks/lorries would damage the drive (the white line running through the photo), particularly as some water was overflowing damming that beavers had done west of the drive at the place marked by the two red markers. 

I should mention that the drive was built in the 1840s with horse drawn carriages in mind. The traffic of lorries weighed down with loads of timber and the destruction this can bring was not thought of at the time. The consequences of tracked vehicles travelling on such a road were unimagined. 

Until recently it was possible to stack felled timber by the side of public roads, but this is no longer allowed.

To cut the story short the dam was breached by the contractor and water flooded down the drive.

The beavers began immediately to rebuild this dam, providing a great opportunity for my trail camera.

At the same time the contractor started to fell timber and stack it by the side of the drive, some of it blocking the old culvert at the lowest blue blob on the satellite photo. The beavers responded to the flow of water that now ran down the west side of the drive by damming it. Eventually, the topography of the land demanded that the water flow across the drive and the beavers began to dam the drive itself. 

All this during a very wet summer: in due course all the timber was removed and the blocked culvert was cleared. 

In December 2012 heavy falls of rain caused the barrage that closes the ponds to the east of the drive to overflow. This caused flooding in the cellar of the gate lodge (to distinguish it from the beaver lodges) at the southern end of the drive. Heavy (relatively speaking) snow in conditions of thaw caused more flooding in January. We arranged for a digger to come and clear a ditch just north of the lodge. This has cured the problem for the time being, but we need still to do some work on the water levels upstream.

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This photograph, looking roughly east across the main pond, shows where beavers are keeping the water open as they swim back and forth. It was taken from the furthest right of the blue blobs.

One of the lodges is shown by the blue blob, second from the right on the satellite photo.

Large woody debris in prone, vertical and angular states, seen from the barrage that closes these ponds.

The barrage that created these ponds was built in the 1890s, I think. It was planted during the 1950s with Norway Spruce, whose rooting systems have been drowned by the raising of the water level brought about by the beavers. 

A few metres on. The dead trees, infested by wood boring wasps, have snapped in the wind rather than been upended on their roots. 

The sluice for the barrage is at its southern end. Since 2002 the beavers have kept it dammed. 

During the various recent attempts to lower water levels a notch was made in the dammed part of the sluice, releasing a great deal of water. As you can see, beavers have been back to repair the damage done to their work by humans.

The last two photographs are roughly where the right of the two red blobs is place on the Google image.

The sluice from downstream.

Looking downstream from the area of the sluice across the swamp.

This photo shows a small enclosure, almost a primitive attempt at a 'beaver deceiver', which marks the entrance to a culvert that goes under the drive. The beavers never tried to block this culvert, so far as I am aware, but raised water levels from the dams downstream made this unnecessary.

The right of the two clear blue blobs marks this on the Google map.

The culvert's outlet is marked by the hole in the ice nearest the camera. There is another hole some yards on and the clear water beyond the felled birch tree marks the beginning of a deeply dug ditch with embankments. The left of the two clear blue blobs marks the emerging place of the culvert.

This is the top dam of that big ditch. A notch has been made in the middle of the dam and the water level has been considerably reduced. Should this be the place for a pond levelling pipe and cage to be installed?

The east side of the dam runs along the bank of the embanked ditch. You may be able to make out the notched bit of the dam that appeared in the previous photo.

A flight of small dams controls the water as it runs south along the ditch.

A small dam filters the water where the embankment has ceased.

The old stone culvert was intact, though somewhat silted, and lengths of plastic pipe were inserted at the inlet and outlet last summer.

This photo shows the line of the embanked ditch. The Google image shows it too if you look for it.

This is our first big attempt at mitigating the impact of beavers. It will be interesting to see how it goes.

In this situation the combination of wet weather through the summers of 2011, 2012, wet winters in both those years, coupled with timber operations, and the work of the beavers have brought about a situation that we need to manage.