Horswell Ditch – nine months after excavation
With the weather forecast to deteriorate tonight, I squeezed in a ringing session this morning. Not the most exciting of days but pretty typical for the middle of June. Just 27 birds of which 7 were recaptures and one a control Reed Warbler. This has probably come from Slapton Ley. Wrens and Blue Tits made up the bulk of the new birds but these also included the first juvenile Chiffchaff and Sedge Warbler of the year.
Things were so quiet at one point that I strolled across to look at the new ditch. The water level has dropped recently, exposing muddy banks but vegetation is already re-establishing after last year’s excavations. There were four species of damselfly and dragonfly present and I spotted a young frog close to the sluice. This is the first amphibian I have ever seen at SML so it looks as though the hoped-for increase in biodiversity has already started!
Another fine day tempted me out again today to complete clearing the net rides. Ringing produced 21 new birds: 1 Blackcap, 1 Blue Tit, 2 Long-tailed Tit, 8 Reed Warbler, 7 Robin, and 2 Sedge Warbler. 16 re-traps included a further 10 Reed Warbler and 2 more Sedge Warbler. There were plenty of juveniles of the resident species knocking about and the first juvenile reed warbler of the year was ringed.
It’s been a while since my last blog entry, partly because of a week off waiting for my stitches to come out but mostly because I was struck down with a particularly nasty intestinal bug, which showed no sign of improving. Tests followed, then more tests, followed by bloods and x-rays before a diagnosis was reached two weeks later. Turns out I had picked up Giardia, a water-borne parasitic flagellate, which attacks the lower intestine, most probably caught whilst splashing through the mud and water at South Milton when clearing the net rides on my last visit. It turns out that David Walliams caught the same bug during his charity swim down the Thames.
Fortunately, things improved rapidly after a course of antibiotics although I’m not 100% even after three and a half weeks. Nevertheless, I felt fit enough to get to SML on 2nd June and face up to the task of clearing the net rides again. I started at the seaward end. These rides had been under a metre of water during the late winter but were accessible now and the soft young reeds only took about thirty minutes to clear. The net rides by the sewage treatment works were more problematic and were at risk of being swamped by hemlock water dropwort. It still amazes me how much bramble and willow can grow in a few weeks as well.
Anyway, I carried on clearing vegetation until my batteries ran out then set up a few nets at about 9am. This turned out to be surprisingly productive, with 68 birds caught and a reasonable variety: 3 Blackbird, 4 Blackcap, 4 Blue Tit, 4 Chiffchaff, 4 Dunnock, 1 Garden Warbler, 1 Goldfinch, 2 Greenfinch, 1 Great Tit, 23 Reed Warbler, 4 Robin, 11 Sedge Warbler, 3 Whitethroat and 3 Wren.
During the years with my former trainers, I used to ring regularly throughout the breeding season at several sites on Dartmoor where Cuckoos were often present. To increase our changes of trapping these difficult birds, I set about making a series of lures using plastic Magpie decoys. In the end I produced three, a male, a female and a hepatic female, which covered all the options and proved reasonably successful in attracting the birds to the netting areas, when used together with a tape. When I changed trainers at the start of 2017, I left the decoys behind, as it has been some years since Cuckoos last parasitized Reed Warblers in Devon’s reedbeds and they would have been little use to me at South Milton.
When we returned from Crete, I received an email from a colleague, who operates a CES on Goss Moor in Cornwall, asking to borrow a decoy. Unfortunately, I couldn’t help but I’ve just had a skin cancer removed from my face and although the area affected was relatively small it’s left a big hole, which needed sixteen stitches to patch it up. Consequently, I’m not allowed to do much as the surgeon has forbidden me from ringing until the stitches come out in a week’s time. Apparently, she considers the mud, stagnant water, sewage outfall and rat and bird faeces at South Milton to be an infection risk! Anyway, to keep things brief, I used the time to make a new decoy – a standard female. Let’s hope it proves effective!
Before and after
My first visit to SML for three and a half weeks and, as expected, the vegetation in the net rides had flourished in my absence. Young reeds are easily dealt with using my rechargeable hedge trimmer but the hemlock water dropwort, which has proliferated in the nutrient rich spoil used to create the paths around the perimeter of the reserve, is a tougher proposition. If left unchecked, the stems of this poisonous plant can reach a diameter of 6cm and once mature, the dry, umbrella-shaped seed heads are a nightmare to remove from a mist net on a windy day. Luckily, almost all the emerging plants were young and tender enough to be dispatched by the hedge trimmer. It will be a constant battle to keep the greenery at bay and the net rides open throughout the summer though.
I had anticipated the vegetation issues and arrived early at 05:30. The main rides were defoliated and six nets erected by 06:30. I cleared another 66m in Crake and Crest rides at the end of the session. On the bird front, things were quiet, with little sign of visible migration other than 19 Whimbrel together with a lone Bar-tailed Godwit in an adjacent stubble field. Clear skies and favourable winds the previous night had given nocturnal migrants no reason to stop. Despite this, 28 birds were trapped including 3 Blackcap, 4 Chiffchaff, 9 Reed Warbler, 8 Sedge Warbler and 1 Reed Bunting. Of the warblers, the majority were males, presumably arriving before the females to establish territories. One of the Chiffchaffs though was clearly female with a fully developed brood patch, indicating that breeding was well underway.
The ringing recovery referred to in my previous post relates to a 1st year, male Blackcap, ringed at South Milton Ley on 16th September 2017 and controlled at Puente de Celemín, Benalup de Sidonia, Cádiz, Spain on 22nd November 2017, a distance of 1,554km almost due south of SML.
No great surprise in the location, slap bang in the middle of the normal wintering area for British-ringed birds in the western Mediterranean but, as this is the first ever foreign control of a Blackcap in nearly 50 years of ringing at SML, I think I am entitled to a moment of smug self-satisfaction!
The map above, cropped from the BTO’s Birdfacts webpages, depicts foreign ringing and recovery locations of Blackcaps encountered in Britain or Ireland. Purple dots indicate locations where birds that have been ringed in Britain or Ireland have been found and Yellow dots indicate ringing locations of birds subsequently found in Britain or Ireland.
I’ve just returned home, after two weeks in sunnier climes, to find a BTO – Ringing Recovery Report sitting in my Inbox. The bird in question was a Blackcap, ringed at SML and controlled in southern Spain. The use of the word “Recovery” started me thinking about the nomenclature employed by British ringers and use of the terms Control, Recovery and Encounter in particular.
My personal view is that a Control is a ringed bird, which has been caught elsewhere by another ringer subsequently and released unharmed to go on its merry way. In the darker reaches of my head I tend to think of a Recovery as relating a bird, which has met either a natural or untimely death and ironically, the one thing it won’t be doing is recovering any time soon!
However, in BTO-speak, a Recovery is a subsequent encounter with a ring, irrespective of whether its owner was alive or dead, re-captured by a ringer, found under a window, brought in by the cat or whether the number was read through a telescope. Note the use of the word Encounter in the previous sentence. This now replaces both Control and Recovery in the latest, on-line version of the BTO’s ringing software – DemOn, where all contacts with a ring from the date of ringing onwards are referred to as Encounters. Grudgingly, I think this makes sense as it encompasses all possibilities by which a ring number could be recorded, and I cannot think of a more suitable alternative, despite scouring a thesaurus.
I’m struggling with the demise of the Control though. It still seems the most appropriate term when a ringed bird is subsequently recaptured elsewhere. There are checks involved. It is a form of control where the ring number, identity, age and sex of a bird are recorded and is not dissimilar from the process at UK airports. I suspect it will be some time before I return from holiday overseas via Passport Encounters or the nice man from Building Encounters comes around to check I have used the correct size beams in my new extension!
I have just finished preparing a ringing report for SML for 2017, partly because Natural England have sent me a copy of their rules relating to bird ringing on SSSI’s, which says a report should be submitted to them annually, but principally because I think that data is of no value unless it is in the public domain. Copies have been sent to Natural England and to Devon Birds for the Harrier.
Chris Townend’s assessment of the bird reserves owned or managed by Devon Birds in 2015 recommended that: “All reserves should have realistic, species specific targets for birds breeding, wintering or on passage. Measuring the success of such targets can only be carried out through regular and accurate monitoring.” The current SML management plan also highlights areas where contemporary data on the flora and fauna of the reserve are inadequate or lacking and the need to address this shortcoming before future changes and the impact of habitat improvements can be assessed. With this lack of data in mind, ringing continued throughout the breeding season in 2017.
Historically the principal focus at SML has been on ringing migrant birds during spring and autumn passage but, as the migratory routes of most of the species there are already well understood, the focus has now shifted to more demographic based studies. For the first time, in recent years, ringing took place in every month and continued throughout the summer. This will enable changes in population, survival and productivity rates between years to be monitored in the future at SML.
Overall it was a productive year with significant improvements to the ringing infrastructure leading to a total of 2,137 birds processed, including nearly 1,200 warblers, and the data collected will form the baseline for future comparisons. You can read the full report here: Annual Ringing Reports
A windless morning with a thin layer of high cloud saw me back at SML just after dawn. It was a little bit warmer and a little bit busier today, although still best described as slow and steady. 32 birds were trapped of which 21 were new including 14 Chiffchaff, 5 Blackcap and 3 Willow Warbler. The Spotted Crake remained on site, calling just twice at 07:30 and 09:15. It has been completely elusive, despite the best efforts of numbers of hopeful observers, and isn’t responding to tape lures any more. I did get good views of a Water Rail in the same area of reedbed though as a consolation. The whole reserve remains exceptionally wet and the fact there are still rails present and they have ceased calling and gone into stealth mode reinforces my belief that there may be several pairs attempting to breed this year.
On a non-bird note, I was tipped off by a visitor last Sunday that there was an unusual flower growing in the upper Ley. Risking life and limb and nearly parting company with my wellies in the process, I managed wade through a particularly wet and overgrown swamp to secure the photo above, which I think is Arum italicum, based on the colour of the spadix and the lack of purple around the margin of the cowl. Separation from the native Lords-and-ladies or Cuckoo Pint, Arum maculatum is not easy for a non-botanist with limited reference books but, either way, it will be a new species for the reserve’s plant list!
After another unproductive session on the 26th March, which certainly wasn’t worth blogging about, with just three new Chiffchaffs ringed, and with a forecast of a clear skies and no wind I was anticipating a decent day at SML and it started well. Arriving at 07:00, there was still a thin layer of frost on the ground and on the mist net poles, and I made my way to Marsh Ride to erect the nets when I was amazed to hear the unmistakeable whiplash call of a Spotted Crake just a few metres away from me. Despite my best efforts I couldn’t see the bird although it responded well to my attempts to imitate its call. It called again briefly a couple of hours later and that was it. I am reliably informed that this is the first spring record for the area.
On the ringing side, things weren’t exactly hectic with 19 birds trapped of which 12 were new including 4 Chiffchaff, 3 Willow Warbler and 1 Goldcrest. Re-traps included a male Cetti’s Warbler of unknown origin and female ringed as a 1st year bird at SML in 2016. This is good news as Cetti’s have been very quiet here for the last couple of years and it’s nice to know that a pair is present at the start of the breeding season.