Drone image looking northeast along the length of South Milton Ley Nature Reserve
Back at SML after a week’s ringing at Portland Bird Observatory, the highlight of which, for me, was ringing two Wrynecks. There was a little gardening required in the main reed bed net ride before I could start as a torrential thunderstorm during my absence had flattened vegetation into the ride. This done, the ringing was steady rather than exceptional and I even had time to cut in a new 6m ride in an attempt to intercept birds moving down a bordering hedgerow.
Combined totals for both days were: 3 Blackbird, 14 Blackcap, 2 Blue Tit, 3 Chaffinch, 35 Chiffchaff, 4 Dunnock, 4 Great Tit, 3 Meadow Pipit, 2 Reed Warbler, 4 Robin, 1 Spotted Flycatcher, 2 Willow Warbler and 3 Wren.
It’s been relatively unusual for me to manage two visits in the same week this year but a stable high pressure over the UK provided a welcome weather window. I was joined on both occasions by Paul Salaman and his wife Sara. Paul has a long history in British ornithology and rang on occasions at South Milton with Bob Burridge before transferring his interests to South America, which culminated in the creation of a national park and a network of private nature reserves in Columbia and the description of four bird species new for science. As CEO of the Rainforest Trust from 2012-2019 he raised $118 million and allocated $105 million in project funding to purchase and to protect over 40 million acres of critical wildlands to save endangered species in 60 countries across the tropics. By comparison, the 42 acres at SML and my own contribution to conservation seem like small fry but I guess it all counts.
Unfortunately, despite favourable winds from the NE, Sunday night had been cloudless with a full moon and most birds seemed to have taken advantage of the opportunity and cleared out by Monday morning, resulting in what was probably my lowest ever catch in August. Just 15 new birds and no Sedge Warblers at all: 1 Blackcap, 1 Cetti’s Warbler, 1 Chiffchaff, 1 Great Spotted Woodpecker, 4 Reed Warbler, 1 Song Thrush, 1 Sparrowhawk, 3 Tree Pipit, 1 Whitethroat and 1 Wren.
Sod’s law being what it is the woodpecker and Sparrowhawk both turned up in a net within 20 minutes of Paul and his wife leaving.
Friday was a little busier but certainly not up to the usual pace of a morning in August with 34 new birds including: 2 Blackbird, 1 Blackcap, 1 Blue Tit, 5 Chiffchaff, 1 Garden Warbler, 1 Grasshopper Warbler, 1 Great Tit, 1 Great Spotted Woodpecker, 1 Long-tailed Tit, 5 Reed Warbler, 2 Robin, 4 Sedge Warbler, 1 Tree Pipit, 5 Willow Warbler and 3 Wren.
Today was one of those bread-and-butter days with enough birds to keep me occupied but sufficiently spread out to avoid any unwelcome stress. A few dark clouds on the horizon briefly raised anxiety levels mid-morning, especially as there was no mobile phone signal, meaning that the rainfall radar app. I normally rely on was out of action. This gives me an audible warning when precipitation is within 20k of the site, which is just about enough time to get all the nets furled before a shower arrives. In the event, I made a judgement call and carried on.
At the end of the session, I made my way across to Horswell Ditch. The leaking sluice was repaired earlier this year and it’s now holding the intended amount of water. Unfortunately, an invasive alien aquatic plant from southern Africa, Lagarosiphon major, known as curly-leaved waterweed, has established itself and spread uncontrollably, floating just below the surface. Whether this arrived naturally or was introduced by a well meaning but ill-informed member of the public is open to question but it’s here to stay.
Curly-leaved Waterweed Lagarosiphon major
However, every cloud has a silver lining. A bit of research revealed that it is an ideal soil improver and compost accelerator. The soil on my allotment in Plymouth is heavy clay and desperately needs organic matter to improve its quality. Other plot holders use seaweed in vast quantities but I am reluctant to collect this from the natural environment so the waterweed provides a sustainable alternative. Using a grapple on the end of a length of rope, I can drag an appropriate amount onto the bank, where I leave it for a couple of hours to drain and to allow any organisms to get back into the water before bagging it and driving it back to Plymouth. A win-win situation!
On a more positive botanical note, for the first time in over a decade Broadleaf Cattail typhus latifolia has appeared in places along the northern bank of the ditch. This species had gradually disappeared from the reserve as the water table fell, a consequence of excessive ditching operations in the past. However, the open water and unshaded banks of Horsewell Ditch seem to have provided long-dormant seeds with the right conditions to re-establish. A favoured winter food source for Reed Bunting and Bearded Tit it’s a welcome return and an indication that Horswell Ditch may be achieving its objective of raising the water table in one of the drier parts of the reserve.
Garden Warbler – 10th August 2021
Back to the ringing. 64 birds were trapped with just four re-traps amongst them. This included the first two Grasshopper Warblers and the first three Garden Warblers of the year. Totals were: 3 Blackbird, 4 Blackcap, 1 Bullfinch, 3 Cetti’s Warbler, 3 Chiffchaff, 3 Garden Warbler, 2 Grasshopper Warbler, 6 Reed Warbler, 3 Robin, 21 Sedge Warbler, 14 Willow Warbler and 1 Wren.
Getting to South Milton has been a bit of a struggle in the last month or so and keeping the blog up to date even more so. Suitable weather conditions for ringing always seem to clash with my shifts at Home Park mass vaccination centre. At present I feel that getting the vaccine into the arms of the hesitant has to take priority. On the few days when I have managed a ringing session the gap between visits has meant more vegetation to clear before I can get the nets up and, frustratingly, the numbers of birds have been low as well. The table below shows just how much Covid has impacted on the number of sessions in the last two years.
There have been three visits on the 8th and 22nd of July and 3rd August since my last report. The combined total is 116 birds processed of which 104 were new with 11 re-traps and one control. The controlled bird was an adult, female Sedge Warbler with a UK ring, which initially caused me some confusion. The ring string I am currently using for this species is prefixed AVJ as was the ring on the bird in question, which made me assume that it was a re-trap. However, I always ring on the right leg with the ring orientated so that it is the correct way up if a bird happens to be photographed in the field. This bird had an inverted ring on its left leg. On closer inspection, I realised that my ring numbers begin with 7 whilst the control ring started with 1. This is the first time I’ve seen the ring numbers coinciding like this and I assume it must be a pretty rare event. I routinely check for rings on the left leg after inadvertently adding a second ring to a Blue Tit in the past. Just one more thing to look out for in the future!
Totals for the last three visits are: 9 Blackbird, 16 Blackcap, 2 Blue Tit, 1 Bullfinch, 23 Chiffchaff, 5 Dunnock, 1 Greenfinch, 1 Great Tit, 1 Great spotted Woodpecker, 15 Reed Warbler, 5 Robin, 9 Sedge Warbler, 2 Song Thrush, 5 Willow Warbler and 9 Wren.
This was one of those days when I think I would have been better off staying in bed! Leaving the house at 04:30 for what, at that time of the morning, is normally about a forty-minute drive to SML I was surprised to find the A379 closed at the turn off for Holbeton. I retraced my steps back to a diversion sign and headed off into the unknown only to find two further diversion signs pointing in opposite directions at the next T-junction. With no mobile phone signal at that point, I guessed right and headed off down a series of narrow lanes past places I had never heard of until eventually I saw a sign to Aveton Gifford. I finally arrived at South Milton at 06:15, almost an hour later than planned.
Things did not improve from that point on. I erected the two nets beside the sewage works without any issues and furled them before setting off to the main reed bed net ride. A five-metre-tall willow tree had come down across the main path, but I managed to scramble through the upper branches to reach the point where Marsh Ride used to be. I say “used to be” quite deliberately as the ride and access bridge were completely blocked with vegetation. A lesson learnt! I hadn’t used the ride for about five weeks, which I now know is long enough to allow the reed and water dropwort to completely take over.
It was not a pleasant experience pushing through waist-high greenery, covered in early morning condensation, and I ended up soaked from the waist down. Forty minutes with my hedge trimmer and two rechargeable batteries later, the ride was just about clear enough to get the nets up and operational although there’s still about an hours’ work left to tidy up the margins and reveal the wooden boardwalk underneath all the cut vegetation. Time to dry off and have a hard-earned cup of coffee!
The ringing was steady until about 11am with thirty birds trapped, twenty-two of which were new. There was nothing unexpected, but the first juvenile Reed and Sedge Warblers of the year were a positive sign. With just two birds trapped in the last hour, I packed the nets away and started to clear the fallen willow tree. I carry a variety of tools including a couple of branch saws as it’s not unusual for one of the young Elms beside Blaca Ride to succumb to Dutch Elm disease and topple across the ride. However, the eight-inch diameter of the fallen willow, which was still attached to the main trunk was hard work to saw through before I could, just about, drag it off the path and out of the way.
Totals were: 5 Blackcap, 1 Blue Tit, 7 Chiffchaff, 1 Dunnock, 1 Great Tit, 5 Reed Warbler, 4 Robin and 6 Sedge Warbler.
I’ve been volunteering at the Covid mass vaccination centre at Home Park, Plymouth, which has curtailed ringing operations a bit, but today a day off coincided with a decent weather forecast so South Milton beckoned.
After the disappointing catch on my last couple of visits I decided to open the two net rides to the east of the sewage works rather than the main reedbed ride. These are on the edge of an area of wet woodland and I had completed preparatory work on my last visit, replacing posts and guys and lopping off overhanging branches.
Together with the nets beside the sewage works, these proved to be quite productive with 47 birds trapped, only 11 of which were re-traps. Twenty recently fledged Chiffchaffs dominated the catch. Totals were: 5 Blackbird, 4 Blackcap, 23 Chiffchaff, 1 Dunnock, 1 Great Tit, 4 Reed Warbler, 1 Robin, 5 Sedge Warbler and 3 Wren.
Despite appearances and the best part of a month of rain and high winds, I have managed a couple of ringing sessions at SML. They were so unproductive that I struggled to motivate myself to update the blog. Five hours on the 7th May resulted in just 12 birds, only four of which were new and another five hours yesterday, (27th May), was only slightly better, producing seven new birds and fifteen re-traps.
A high proportion of re-traps is to be expected during the breeding season, especially as the spring migration seems to have come to an end. The best of these was a Reed Warbler first ringed as a juvenile on 9 August 2014 and, even better, a second Reed Warbler, originally ringed as a juvenile on 7 August 2010, almost 10 years and nine months ago, meaning that the bird has made an astonishing twenty-two trips between the UK and Africa. There is still some way to go to beat the BTO record age for the species of 12 years 11 months 21 days.
In between net rounds, I continued to gather evidence to support my case against the excessive dredging of the drainage ditch on the northern side of the reserve. Historically, an increase in the area of reed at the eastern end of the Ley was much publicised, although this was actually the direct result of fencing the perimeter and the exclusion of livestock and grazing rather than management of the water levels. The loss of almost 14,000m2 of reed, since the year 2,000, due to drying out of the reedbed has, understandably, generated no publicity at all from the reserve manager. One result of the lowering of the water table has been the uncontrolled spread of Hemlock Water Dropwort at the expense of reed. The photo below compares the middle Ley in 2010, with about 50% reed, with the situation yesterday and clearly illustrates the total loss of reed in the area. The yellow line of reed in the right-hand picture marks the demarcation zone between the dry eastern part of the reserve and the wettest part of the central Ley, (at about 650m from the eastern boundary.
Looking SW across the Ley in 2015 (left) and 2021 (right)
If I’m honest, after the photos have been scaled to fit on the screen, it requires a bit of imagination to see the difference between the two images. However, thanks to Google Earth, the following aerial shot better illustrates the point I am trying to make. Taken on 30th May 2020, a time of year when the Hemlock Water Dropwort has already reached between 1-1.5m in height and is starting to produce flower buds, whilst the reeds have only reached about 30cm, the paler, silvery green areas show the extent of the dropwort in the dryest region between the public footpath and Marsh Ride, rapidly decreasing in density to the west as it reaches those areas, which are regularly inundated during flooding events. Unsurprisingly, it is particularly abundant along both sides of South Milton Stream, where the elevated and drier banks produced during path construction, together with the spreading of nutrient-rich spoil and fragmentation of its tubers during ditching operations has allowed the species to proliferate.
The extent of Hemlock Water Dropwort (paler green areas) on May 30th 2020 (Image from Google Earth)
In recent years, in collaboration with English Nature, we have been allowing the western end of the drainage ditch to silt up naturally and there has been some improvement, particularly in the central 500m. Exceptional rainfall and a persistent high sandbar in has enabled sediment to deposit in the lower reaches, where the flow is impeded by water impounded behind the sandbar.
The reserve manager has always had a free hand at SML and his work proposals have often been approved without question. Whilst his experience as a groundsman has been useful in managing the grassland and hedgerows around the perimeter of the reserve, his lack of understanding of the principals of hydrology and a preference for “big” engineering projects has meant that almost every intervention involving drainage has had a negative effect on the water table and impacted on the quality and extent of the reedbed. As Nick Baker commented, in his Sept 2019, BBC Inside Out program featuring SML, Hemlock Water Dropwort has been able to outcompete reed over much of the central reserve. Stands of Greater Reedmace have also disappeared as the water table has fallen. The previous dredging was both unnecessary and excessive but the manager seems unwilling to accept this or that there have been adverse impacts.
I am concerned that, once again, the reserve manager is proposing to dredge this channel later this year and I have been lobbying Devon Birds’ Council to ensure this doesn’t happen. The figures below show the surface elevation along the length of the reserve from Mill Lane in the east to the footbridge on the South West Coastal Path in the west. The shaded pink area in the first figure illustrates just how much the water table was lowered following dredging in 1994.
The height of the water table at SML relative to the surface, pre and post dredging in 1994
However, the shaded brown area in the second figure shows the depth of the ditch as measured this month, following a gradual, slow improvement over the last couple of years. The steeper gradient at c. 800m coincides with the location of the boardwalk across the reedbed and marks the point where the flow downstream meets water impounded when the sandbar is intact, allowing sediment to build up. It is likely that the gradient below this point is actually shallower than illustrated but the boundary path deviates to about 15m away from the ditch below the boardwalk and I considered it unsafe to attempt to measure the depth when operating on my own.
Realistically, it is unlikely that there will be much improvement upstream of the public footpath at 400m as dredging along the eastern length of ditch caused a fourfold increase in gradient and the consequent higher flow rate prevents sedimentation from occurring.
The height of the water table at SML relative to the surface in May 2021
Not dredging the ditch will allow sedimentation to continue and the shallowing stream should restore the natural floodplain in the centre of the reserve at the expense of Hemlock Water Dropwort and to the benefit of the reedbed and its associated ecosystem. At the very least, doing nothing and allowing nature to take its course, costs nothing and, if it all goes pear-shaped, can easily be reversed by a man in a hi-vis jacket and a very big digger!
After a completely clear, windless night with a full moon I wasn’t expecting much in the way of grounded migrants this morning and I wasn’t disappointed! Nevertheless, despite the lack of numbers, there was a reasonable selection including eight species of warbler and the first Reed Bunting, Garden Warblers and Whitethroat of the year. A French ringed Sedge warbler provided the icing on the cake, although this is known to be a local breeder, ringed as a 1st year at Trunvel, Treogat, Finistère, France on 6th August 2018 during its first southwards migration. Now returning to South Milton to breed for the third successive year.
Once again, my time was most profitably spent, between net rounds, clearing more grass from the boards in Marsh Ride. With 42 metres of board now fully exposed, just six remain to be cleared during my next visit.
One of the major shortcomings at South Milton Ley, identified in the last management plan, was the lack of comprehensive, contemporary information on the flora and fauna of the reserve and the complete absence of monitoring both before or after major projects, which may have affected species distributions and diversity. Since 2015, I have made considerable efforts to encourage specialist teams to visit the reserve and the fruits of their collective efforts have been considerable.
Whilst this blog primarily concentrates on bird ringing at SML, Devon Bird’s current lack of an archivist causes me concern that, in the event of my sudden demise or that of my pc, many records could be lost. Consequently, I have sent copies of species lists to Natural England, who oversee the SSSI, and made the decision to post copies on this blog as well.
My own contribution to today’s lists is minor when compared to the efforts of visiting specialists and, whilst I have made every effort not to omit anyone, it was safer to name the parent groups rather than individuals and I apologise in advance if anybody feels overlooked.
In summary, since the current management plan was written in 2015:
The number of plant species identified has increased from 95 to 208 thanks to surveys by John Day.
The number of arachnid species identified within the reserve has increased from 10 to 26, thanks to Geoff Foale from Salcombe. Insect species have increased from 130 to 877, thanks principally to the efforts of Geoff Foale and members of the Devon Fly Group. Barry Henwood and members of the Devon Moth Group have increased the number of moths from 6 to 174, whilst Dr Martin Luff has increased the number of beetles from 15 to 192.
In terms of vertebrates the number of amphibians and reptiles remains the same at three and four respectively. One additional fish species has been identified, taking the total up to a majestic three and a comprehensive bird list has been compiled with the assistance of Mike Passman, Bob Burridge and Vic Tucker. Only species recorded either within or flying over the reserve have been included and several rarities, shearwaters, divers, auks and waders, recorded either in the bay, on the beach or at South Huish are now omitted. The current avian total stands at 202 species.
Finally, local resident John Ward has recorded fourteen species of bat adjacent to the reserve and Jess Smallcombe and Ellie Knott of the Devon Biodiversity Records Centre have just provided conclusive proof of the presence of both Water Voles and Otters, taking the mammal total up from 22 to 32 species. Species lists for all of these groups can be accessed here: South Milton Ley Species Lists
Another cold and frosty start greeted me this morning and, for the second time in a row, conditions were almost perfect for ringing with just a gentle NE breeze and clear skies. However, the persistent blocking area of high pressure over the UK seems to have stopped migration in its tracks with birds being held up in N Africa and S Europe. It was as if they were observing their own lockdown! An all-time spring low of 18 were trapped in a five-hour session with just six new birds amongst them. The first Sedge and Reed Warblers of the year and three passage swallows provided a glimmer of hope but my time was more profitably spent continuing to clear grass from between the boards in Marsh Ride using hand shears.
