The Riverfly Partnership was established in 2007, comprising nearly 100 organisations including anglers and conservationists. Their objectives are to work together nationally to protect and improve the water quality of our rivers, preserve habitats and study riverfly populations.
The scheme reached our area early in 2014 through an initiative from the North Devon Nature Improvement Area (NIA), itself driven through the Devon Wildlife Trust. The aim is to get volunteers involved with sampling of invertebrate life in the Torridge catchment area, which will help with long term monitoring of the river’s health.
We are pleased to say the Brandis Corner Wildlife Group is taking part, with four members undertaking a training day. We were issued a free sampling kit and in late July, monthly sampling commenced at the volunteer nominated sites. In a normal year, sampling will be from April to September.
Sampling involves using a standard replicable method to record the presence and numbers of bottom living invertebrates of seven indicator families of flies and a freshwater shrimp, over a four-minute time period and then recording the results through the Riverfly Partnership’s website http://www.riverflies.org. The indicator families reflect the different degrees of tolerance those species have to pollution and the data derived from them is turned into an index, which is measured against a trigger level for each site. Investigation and action is taken by the Environment Agency if the index falls below the trigger level.
The NIA is very impressed that 34 people in the Torridge Catchment area have been trained for the project, sampling 29 separate sites. It is pleasing to know that BCWG is contributing to this scientific project and fascinating to see what the results will be for 2015.
UPDATE – THIS YEAR’S SAMPLING
It has been a mixed year in terms of invertebrate sampling for Alan and I in that flooding on the Torridge during August and September made sampling impossible. On one occasion, our sampling site was approximately six feet under water! Our own availability and the weather itself (it is almost impossible to sample when it is actually raining) compounded the issue.
Never mind, we still did four samplings – April to July, which we found as absorbing and rewarding as ever. A summary of our results this year has been kindly supplied by Matt Edworthy – see it by clicking here. As you can see, all our sampling is well above the trigger level 8, meaning that water quality is good. Note that our site is described as Bradford Mill, when in reality it is at least half a mile upriver from there. (This is because the nearest site for which historic data from the Environment Agency is available is Bradford Mill from which the trigger and comparison is derived)
Matt also shows results for the whole Torridge catchment and is heartening to see that samples below and at trigger levels have more than halved from last year to this. This could be through natural causes or a function of the developing expertise of surveyors over this initial period. It will be interesting to compare subsequent year’s data.
Barrie Lewis & Alan Rowland
4th Dec 2015
Riverfly Monitoring – Geoffrey Pitt, 27th Oct 2015
This was my first year of monitoring. I have two sites, the first of these is one of the small streams that feed into the Torridge, the tributary of Cookbury Stream that runs through Bramble Wood. I found a quiet spot away from dog walking areas. The water level is shallow and I did not know what I would find. I have found Caddisflies (cased and caseless), Up-wing flies (Mayfly, Olives (including Blue-winged), Flat-bodied up-wings), Stoneflies and Freshwater Shrimp. I sampled the stream in May, June, July, August and September. Mayfly, Caddisflies (cased or caseless) and Blue Winged Olives were not found in some samples, but on each occasion the general level of abundance of river invertebrates was higher than the trigger level.
Abundance Trigger level 4, Results 10, 10, 9, 7, 9. So no water quality concerns were raised.
For the Torridge (Kithill site) I had some help, I was always accompanied by another adult. I collected samples from the Torridge up river from Dipper Mill. On the river the total number and variety of invertebrates were greater than from the stream as you would expect and took longer to sort and count even with help. After the extended period of rain in August the Torridge was flowing too high to allow safe sampling.
I collected samples in April, May, June, July and September.
Abundance Trigger level 8, Results 14, 14, 13, 13, 13
Riverfly Monitoring – Jan Mallik 25th Oct 2015
This season’s river sampling has been exciting, but complicated by the weather. Just to remind you, those of us involved take a sample of the invertebrates which live on the weed, stones or in the sand or gravel in our chosen stream or river. The Environment Agency has set a ‘trigger level’ for each site, arrived at by the quantity of each species they expect to be present, and if that level is breached it means something unusual has happened and either they go to investigate, or we are asked to return and take another sample.
This happened to me at one of my sites during the August sample – there were far fewer of the eight species I had to check, so my trigger level was breached. I wasn’t worried though; it didn’t look as if there was a pollution problem, and I could see there had been a flash flood within the last day or two. However, a fortnight later I was asked to take another sample, and this time the trigger level was just reached. The landowner appeared as I was checking the sample, and she said the flash flood had been the highest she’d known, the water had risen at least six feet, topping the bank and flooding her meadow, so clearly most of the invertebrates had been washed downstream. I was surprised how quickly the population had re-established – although most of the larvae were smaller than normal, they were at least there.
A couple of earlier months were so dry I had to wait until it rained! It’s difficult to sample a trickle of water, but luckily each month there was just enough water for me to take the samples.
The photographs are of three of the upwing fly larvae we count – they turn into mayflies and other similar flies. The actual size of the mature larvae varies between an inch to a third of an inch, excluding the tail, depending on the species.
Sadly this season’s sampling is over, and I have to wait until next April to begin again!
The Poorlands, located near Cookbury, is the name given to a 1.6 hectare piece of wood which was donated to the church as a field in 1850, for use as allotments by the ‘labouring poor’ of Cookbury. It was abandoned about 50 years ago and reverted to woodlands, now rich in ferns, mosses and associated wildlife. In 2014 an important survey was carried out by experts, which revealed 100 species of plants, 20 of which were ancient woodland indicator species. The wood is also important for Lichens, 25 species of which had been logged.
The Brandis Corner Wildlife Group is involved in a project to develop a 10 year management plan for the wood, under the aegis of the church. The BCWG is initiating survey work for dormice and bats in 2015 as part of the assessment for this management plan.
The wood is not open for public access at the present time.
Dunsland Surveys 2016/17
For two years now, myself and Group member David Cleverly have been surveying some of Dunsland’s wildlife for the National Trust. We studied the Dragonflies and Damselflies for both years (ex Group members Sue and Jamie Godwin had studied them in 2015) and birds, this year. More detail on both surveys now follows and I will also touch on butterflies.
We had responded to a request from the Dunsland Ranger Gregg Wilson in 2016, for someone in the Group to continue the survey and agreed with Gregg a method of 10 minutes observation at 5 different points along the poolside fence, with an optional foray through/over the gate to get nearer the pool.
I had also been in touch with one of the country’s leading experts on dragon/damselflies Dave Smallshire, who happens to live in Devon and who gave me some useful tips on surveying. One of these was to go on a sunny day as there is little activity when it is cloudy and to take binoculars. Both points were very useful, as we discovered.
We surveyed from May to August and tried to go once every two weeks in 2016, when weather and our availability permitted. In total, we logged 4 species of Damselflies and 3 Dragonflies, all common species with total numbers peaking in June this year at 177, of which, 151 were common blue damsels. One of the most attractive seen was the female beautiful demoiselle resplendent in her overall coppery sheen when viewed in bright sunlight. Another interesting sight was the 3 emperor dragonflies seen this August, with at least 2 of them being males, which clashed sometimes in the air with a clatter of wings.
I entered the 2016 records into the National Biological Records Centre’s website, which has a section linked to the British Dragonfly Society.
Methodology – As I had been a volunteer in the BTO’s 2007-11 national Bird Atlas, Gregg was happy to “let us loose” on the birds of Dunsland, once I explained we would be conducting it using very similar methodology as that used for the BTO atlas. Basically, this entails visiting the site, preferably in the morning and walking a route taking in the boundaries where possible and all habitat types, each month from April to July for breeding birds and for the winter period, November to February. It should be done in an hour but we stopped the clock when standing in one spot in order to try and identify a particular bird. Species were recorded visually and by song or call alone (as per BTO) and codes used when breeding was confirmed e.g FF (adult carrying food for young) etc.
We also used Roving Records at the site to log bird species not seen during the ‘official’ monthly visits.
Results – The results were interesting: 36 species in total seen/heard, with breeding proved for 10. One of the highlights was seeing a family of 8 ravens in the air together over the old house site in July and we heard a tawny owl calling around 11a.m. near the pool in June.
Strange bird behaviour – I recorded too, a very interesting piece of bird behaviour I had never seen before, involving moorhens at 6.15 a.m. during one of my solo June visits. A pair of adults were on the pool with just one chick about 75mm long and I watched through my binoculars, somewhat incredulous, as both adults took turns to hit the chick with their beaks, sending it under the water. There were two ‘sessions’ of this and after the second one, the chick stayed under for what seemed a long time but was probably only 10 seconds or so. It then surfaced about 2 metres away from the adults, looking understandably dazed and stayed still for a couple of minutes. The adults then went to it and acted normally. What was going on, were they teaching it to dive when danger threatened for example, was the chick ill in some way, or was it simply vindictive behaviour? And what had happened to the other chicks? I was convinced at one stage that the little thing was going to die!
Incidentallly, I was confident the adults were not reacting to me, as I was hidden behind the trees looking through the leaves.
Very briefly, we logged butterflies seen during the bird surveys and were thrilled to see 9 species in one location during a 20 minutes spell in late July and it was truly like the old days of English meadows, in terms of the numbers around us in the air and on the plants – magic!
There is clearly a need for a proper butterfly survey, so David and I hope to achieve it this year.
The results of both surveys are summarised on 2 PDF files below.