Editorial. Contents. Copy deadline. Helpline and LBG contact telephone number. Newsletter of Lincolnshire Bat Group Volume 26 Issue 2.

Transcription

1 Newsletter of Lincolnshire Bat Group Volume 26 Issue 2 Editorial Contents Editorial 1 Copy Deadline 1 Helpline number 1 Stourton Cellars 2 Records! 2 Hibernation Counts Village Bat Walk 3 More Unusual Bat Roosts 5 Welcome to the second newsletter of 2012 from Lincolnshire Bat Group. It doesn t seem very long since the last issue, probably because we are still waiting for summer to arrive Yet again the plans of things that wanted looking at seem to have gone by the wayside. This issue sees some interesting articles on work the Bat Group have been doing during There have been many shows and events over the last year and there are further opportunities for some personal encounters with bats on the hibernation surveys in early Numbers will be limited so please get in touch as soon as possible to secure a place on the counts. There will also be other shows and events next year so keep checking the website for news of these Bats in the Fens 3 Ian Nixon Diary Dates 5 The Scotter Bat Roost 6 Who s who? 8 Copy deadline Please send any articles or other bat related copy for the April issue of BatLincs to Ian Nixon by 17 th March Diary Dates 8 Many thanks Ian Helpline and LBG contact telephone number BatLincs November 2012 Page 1

2 Stourton Cellars Many Bat Group members will be familiar with Stourton Hall cellars which have been regularly visited since 2006 as part of the National Bat Monitoring Programme. In winter, the cellars regularly hold numbers of Natterer s and Daubenton s bats. Brown long-eared bats hibernate there occasionally and the cold weather of February 2012 drove two barbastelles into the cellars for the first time on the NBMP surveys. The site comprises 3 cellars and an interconnecting passage of high quality brickwork with few of the missing-mortar niches that are found in most of the other NBMP hibernation sites that the Bat Group visits. have been a storage cellar so that they were as high above floor level and rodent predators as possible. Since the Bat Group put up the roost piles only a few bats have used them. One of the possible problems was that the gaps left between the bricks was too wide and in order to address this problem, Ian Nixon, Sue Turner, Helen Scarborough and Nick Tribe visited the site on 3rd October to improve the roost piles and put up more wooden roost niches. It was a lovely warm, sunny, autumnal day what better way to spend an afternoon than underground It is tempting to suggest that lack of roost niches is a limiting factor for numbers of hibernating bats although perhaps this applies to smaller roost sites as niche availability in our railway tunnel hibernation sites does not appear to be a limiting factor for bat numbers. It will be interesting to observe whether bats find and use the (hopefully) improved roost piles and wooden roost niches; but as we all know, bats can be ungrateful critters at times Nick Tribe In 2010, with the permission of the site owners, Bat Group members made the stairs safe by clearing debris and took the opportunity to increase the number of niches by building bat roost piles from the bricks lying around on the floor. Records! If you have records to send me it would be really appreciated if you could get them to me as soon as possible after Christmas, and certainly by the end of January. Record keeping these days is a fairly mammoth task and the winter months are when I have the most time to do them. Once we get into March other priorities start to take over and I have less time to spend on them. ALL records are welcome, including the bat(s) you record over your garden, with or without the aid of a bat detector. If you use the recording form on the website, that asks for all the info needed. If you don't have a computer it's probably best to contact me on and we can do it over the phone. Many thanks. Annette The piles were put up on the shelves of what appears to BatLincs November 2012 Page 2

3 Hibernation counts 2013 Day Date(s) Location Leader Saturday 12 th January 2013 South Elkington/Stourton cellars Helen Scarborough Sunday 13 th January 2013 Withcall/South Willingham Tunnels Dave Hughes Sunday 20 th January 2013 Toft Tunnel Barry Johnson To be confirmed Harlaxton Manor Annette Faulkner Sunday 27 th January 2013 Lincoln Castle/ Bishops Palace Nick Tribe Saturday 9 th February 2013 South Elkington/Stourton cellars Helen Scarborough Sunday 10 th February 2013 Withcall/South Willingham Tunnels Dave Hughes Sunday 17 th February 2013 Toft Tunnel Barry Johnson To be confirmed Harlaxton Manor Annette Faulkner Sunday 24 th February 2013 Lincoln Castle/ Bishops Palace Nick Tribe There will also be surveys at Tattershall Castle and Tattershall Carrs these will be mid-week and anyone who is interested can contact either Helen Scarborough or Ian Nixon (see Who s who for contact details or the helpline number on page 1). Although somewhat more distant time wise there will be a further check of the bat boxes at Tattershall Carrs in April. Please contact Ian Nixon for more information. A Village Bat Walk at Sutton St James Last year we were asked by Natural England to survey Sutton St James church, as they needed some repairs doing. We had never surveyed the church before but had been past it plenty of times, and knew there to be brown long-eared bats roosting there. Because the repairs were likely to affect access points we needed to do an emergence survey. We enlisted the help of a local Bat Group member, but as the church warden and the vicar were both extremely pro bat and interested, they came along too, along with the other church warden and the vicar's mother, so it turned into quite a party. roost in the belfry. The churchyard is very nice not over managed and full of mature trees so we not only had a long-eared or two out of one of the anticipated accesses, we had both soprano and common pipistrelles foraging in the churchyard. Which had come from the belfry roost? And where had the others come from? Thus was born the idea of having a village bat walk, where villagers had a short introductory bat talk, some basic training on how to use a bat detector, and then a series of short walks along the village streets with a map to record what they heard. I had no idea whether it would work, but the church warden was very enthusiastic so we decided to give it a go. In the course of our original survey the church warden had also taken us up the tower, which wasn't included in the repairs and lo and behold, there was a genuine (pipistrelle) Fast forward to September this year: The church warden did much of the organisation at the village end see the brilliant poster she did while I set to work with the map to BatLincs November 2012 Page 3

4 create 12 walks of 1 1 ½ km long, that people could either walk in both directions or take two cars and walk one way only, and as the South Holland Main Drain passes just to the north of the village we included sections along that as well, as there is a well maintained bridle way the full length. I'd asked the church warden to let me know approximately how many people to expect around 35! - and the church was full. Some just came for the bat talk at the beginning, but approximately 20 people had come to do the walks as well. We explained that they were pioneers, did the basic training both inside and out in the churchyard and to my relief almost immediately had bats. With a northerly wind and a temperature of 7.5 C were we going to get any? One family had been unable to come, but nine of the twelve walks were taken, and we did the tenth. They took from twenty minutes where recorders hadn't done the full length - to an hour to complete and we all reassembled back at the church afterwards. I had also taken the precaution of adding a couple of feedback questions and space for comments at the bottom of the written instructions that they had, which most of them filled in. sopranos ('if in doubt just put a cross'), and how to screen out pipistrelles so that they could hear the Daubenton's if along the Drain. And most of them managed this. Gratifyingly, the two ladies who did a section of the Drain upstream from us had exactly the same results as we did. There were a number of pipistrelle sp recorded at 50kHz, but where they were able to separate them they found nearly all were common pipistrelles. One lady, who'd been on a bat walk before, was convinced she'd had a noctule, with several records down in the 20s, but this needs verifying, and one group didn't really manage very well and we went back to check that one out. - nearly all common pipistrelles, as noted below. But apart from that the rest of the results are entirely consistent, have flagged up a few hotspots, and have simultaneously recorded common pipistrelles across much of the village, giving a much better idea of the overall population. The advantages from our point of view were a) that we could do it without extra help, apart from at the local level this was essential, as it would have been very much harder to do without the church warden's help in getting people organised; b) it's an excellent way of getting people involved (some of them were really fired up and are already asking if we can do it again next summer); and c) it's a brilliant way of collecting a lot of basic records in a short space of time. The organisation is quite simple you need a local person to prepare the ground, the equipment for a short bat talk, a set of enlarged maps, the detectors when no-one else needs them (which requires forward planning of course), and a meeting place. If anyone else with bat detector skills wants to have a go next year, I can provide the instructions and any further info. Annette When we got home I had a look at the results and they were quite amazing. The distance they found about right and they found using the Magenta detectors easy to fairly easy. I had explained how to distinguish common pipistrelles from BatLincs November 2012 Page 4

5 More Unusual Bat Roosts Bats in the Fens, an interesting discovery After 'bats in sacks' (BatLincs May 2011) I didn't think I would come across another example but, as you can see, they pop up in all sorts of places one might not expect! This example from an Estate near Grantham arose from a chance conversation with the gamekeeper; who seemed quite taken with 'his' bats, with whom he had spent many a summer s evening in close proximity listening to their awakening rustles and scratches, and subsequent emergence to forage in the ride overlooked by the deer observation tower (polite phrase for shooting gallery). This summer I have been out with a botanist on a number of surveys of the big Fenland drains in South Holland. Although I'm a reasonably able botanist when it comes to terrestrial plants and a lot of the plants at the fringes of the drains, I knew comparatively little about aquatic plants. What I did know, however, was that a lot of invertebrates associated with riparian and fringe wetland habitats which have varying degrees of rarity across the rest of the country and which are listed in various 'Red Data' books, are relatively common here it's just that not many people have ever got round to looking (it's flat, boring, full of cabbages and wildlife free...), until a few English Nature (now Natural England) entomologists decided to have a look a few years ago, when they found all sorts of interesting stuff. What I also knew was that a lot of the past abuses by various internal drainage boards eg where they stood on a bridge and tipped herbicide into the water have long ago ceased, and water quality is generally pretty good. More unusual was the roof construction - corrugated tin sheeting nailed over a multi-ply sheet. How many times might we dismiss this in a farmyard shed / house lean-to as an unlikely medium for roosting; and focus attention more on slate roofed stone buildings, or underfelted pantile roofing? Dredging up weed with a hooked device called a grapnel was a real eye opener, and many of the drains had upwards of 5 or 6 species liberally deposited on the bottom. At the fringes too there were plants I'd never seen before, including some very rare ones. What all this means in biodiversity terms is that the more species of plants you have the more species of invertebrates you are going to have. Bat food! As I was not there for the bats, and during the working day, I don't know what the species was - perhaps next year I'll join the shooting set and armed with my trusty SM2 detector, find out just what they are. Graham Colborne So then I started to look at what species of bats were recorded over the drains and added a few more records this year too. And what I have found is that out in the open countryside, away from towns and villages, where you tend to find more species, these drains appear to exclusively support common pipistrelles and Daubenton's bats, both of which are indeed very common here. Is this true elsewhere, such as over the big drains in the Isle of Axholme and north and west of Boston? Would anyone like to have a look next year? Annette BatLincs November 2012 Page 5

6 The Scotter Whiskered Bat Roost I first discovered something interesting was happening in my house in June It was the morning of my first ever sunrise survey and I was out of bed an hour earlier than I needed to be, playing around with my Ciel bat detector well before the scheduled start of 5.30, an hour before sunrise. Nothing much came of the survey. Everything happened before that and, perhaps improbably, finished at 5.29, exactly one minute before the official start of the survey. That was the time when the last of 29 bats, flying at approximately one minute intervals, flew into the valley between two roof pitches of my house. They all came from the direction of the River Eau at the bottom of my garden. I m not brilliant at field identification now but I was even worse then. I was certain however that they were not pipistrelles. They didn t have the complex quality of ultrasonic emissions of pipistrelles and they had no obvious peak frequency. They were more clicky and there was little change in pitch across a wide range of frequencies. I knew that meant they were myotids but I could say no more about them. None of them counted as part of the sunrise survey, the last one having missed inclusion, of course, by just one minute. Quarries Nature Reserve and Daubenton s are known to forage over them. However, the River Eau does not connect with the Reserve. In the autumn, I went into the roof space. The bats had gone. There was plenty of evidence of their previous presence in the form of droppings which were distributed at the base of a chimney and directly beneath the central ridge beams. There were also a couple of areas of droppings elsewhere. We had roof insulation laid down in 2004 and the builder who did it remembers bat droppings at the time. So, it looked like, whatever the identity of the bats was, they were possibly annual visitors. I took a sample of droppings to Dave Hughes and we compared them to a database that he had. They most resembled pipistrelle droppings, which was a bit disappointing. It also made things a bit more complicated. I was already convinced that I had a Myotis roost but now there was the prospect of pipistrelle coroosting. About one month later, I was stood at the window of my bedroom, having spent an hour earlier detecting pipistrelles at the back of the house. It was after 11pm. I saw two or three bats fly past the window from the direction of the roof valley. This was well after the pipistrelle activity had subsided. I tried recording the bats one morning. The equipment I used was poor quality and, again, I didn t really know what I was doing. I was very dependent on Ian Nixon to help me with the interpretation of the sound files and it was an interesting 15 minutes at the LBG meeting when he and I looked at the sonograms on his laptop. Ian showed me the parameters for helping to identify bats from sonograms, including shape of spectrum, inter-pulse interval, duration of pulse, start and end frequencies and maximum frequency and we compared the parameters with the sonograms. There was nothing definitive, apart from the confirmation that they were myotids, but the Inter pulse frequency suggested (tantalisingly) that they might be Daubenton s. As we know, Daubenton s don t usually roost in domestic dwellings. The nearest lakes are 2.5 miles away at the Messingham Sand Emergence point A very unwelcome discovery in my roof space was daylight. The mortar between most of the ridge tiles had disappeared. I therefore needed to make repairs to the roof. At the same time, the concrete roof tiles on another adjacent part of the house needed replacing and so I decided to have all the repairs and reroofing carried out in one job. Anxious to conserve the roosting conditions, I contacted Natural England for a survey and advice on the best time to undertake the work together with any suggestions for mitigation. Natural England asked a chap called Dave Hughes to do the survey and Dave and I went up into the roof on 25 August The space is quite large and I have boards down to walk on. BatLincs November 2012 Page 6

7 There is a small square hole in the brick wall that separates the oldest part of the house from the part built in A loft ladder accesses the roof of the old house and the Edwardian roof is accessed through the hole. It is this part of the house that the bats occupy. It is south facing and well exposed to sunlight for most of the day in the summer. When we entered this area we were quickly met by a single flying bat. Dave was able to gently pick it up once it had settled and just before it tucked itself into a crevice. I couldn t have hoped for better. An examination of the physical characteristics suggested it was a juvenile whiskered/brandt s. These are usually referred to as whiskered/brandt s because they are difficult to tell apart even though they are genetically very different. Fortunately I had a specimen pot in the house and, with a pair of nail scissors; we managed to clip off a tuft of fur before placing the bat back on a rafter. The fur was posted to Warwick University where it was processed in a DNA Polymerase Chain Reaction (PCR). Two weeks later the result came through from Warwick. This showed that the bat sampled was a Myotis mystacinus or whiskered bat. This was very exciting. I now felt obliged to study this roost but I still needed to make roof repairs I was anxious that the bats may never return. I had no idea where they were gaining their access to the roof and the repairs may consign them to history. I arranged for the roofing company to install some mitigation in the form of lead bat slates, three on each side of the ridge. The repairs proved to be a nightmare. I was told that the existing tiles on the older part of the roof were inadequately supported by the timbers. We needed a custom-manufactured steel girder and extra timber frame to make it all safe. Once the work was completed, I took the opportunity to install electric points, four video surveillance cameras wired to a VCR downstairs in my study, an internal ultrasonic microphone with lead down to a Song Meter detector in the garden, and two data loggers within the roof space. Later, I added a fifth camera on an external wall and trained onto the emergence site. I had found this during one night after recruiting my wife and two daughters to watch around the outside of the house. I also installed a wireless external weather station which radioed data every two minutes to my PC in the study. Loft space (with camera!) Whilst waiting for the results of the DNA analysis, I tried to beat the high tech approach at its own game by examining a dead bat that I found on the floor of the roof. The body was sufficiently decomposed for the skull to be devoid of most tissue and for an examination of the dentition to be possible. Could I tell whether it was a whiskered or Brandt s from the presence or absence of a protocone on the third upper premolar? I took the skull to work where I have access to a plate microscope used to examine colonies of fungi on agar plates. This magnifies to X10 and illuminates specimens giving the best possible view. Despite this, I found it very difficult. I formed the conclusion that, if I were a betting man, I would put my money on it being the skull of a whiskered bat but I was far from certain. Weather station Everything was set up. All I needed were bats. The wait was long and frustrating and I convinced myself that the roof repairs had somehow prevented their return. In the end, the bats surprised me. I suddenly caught sight of them whilst idly watching the images on my PC as I was doing some other work. I believe I must have missed the first night of their return because, by now, it was 25 May and BatLincs November 2012 Page 7

8 considerably later than I would have expected. I started recording them on all cameras and also made recordings inside and out with the Song Meter. At first I recorded for an hour before sunset until an hour after sunrise every day but later in the season I recorded round the clock so that I could detect any daytime activity and, in particular, change of roosting positions with temperature increases. I conducted fairly regular emergence surveys, my wife and daughter having discovered the single emergence point at the front of the house. Luckily, I am able to observe this point from the bay window of my bedroom. There is a street lamp that gives adequate illumination and therefore I am able to get very accurate counts. I tend to do the counts in duplicate over two nights just to add that little extra reassurance. In May there were 49 bats. By the end of July there were 82 and by the end of August there were 33. I did not manage to do a duplicate count to confirm the 33 and it may be that the numbers were on the way down at that time, but it is intriguing to note that 82 minus 33 is 49. Perhaps the mothers had all left the roost and only the juveniles remained? It had been a bad year for weather and yet the delivery of live young and their survival to independent flying and foraging was 67%. I do not know what an expected survival rate would be but it should be high for a species that only has one young a year. As I write this, there are four bats that have stubbornly remained in the roof after all their roost mates have left for the winter. I am now only running one internal camera and one external. I am still collecting data logger and weather data but have stopped the sound recordings and the dropping collection. Some of the video is exciting to watch. There are mothers carrying their young in flight and some of the interaction between bats is fascinating. There is so much to learn from what I have done already. I have over a terabyte of data in storage. Guess what I ll be doing this winter! Peter Cowling Who s who? Chairman: Dave Hughes serotine666@yahoo.co.uk Secretary: Helen Scarborough & Clare Sterling helenscarborough@tiscali.co.uk csterling@lincstrust.co.uk Membership: Elizabeth Biott ebiott@lincstrust.co.uk Treasurer: Records: Ruth Snelson rutysnel@msn.com Annette Faulkner annettefaulkner@btinteret.com Newsletter: Ian Nixon ian.nixon99@btconnect.com Training: Ian Nixon and Dave Hughes Mission control Another study that I am undertaking is the collection of weekly droppings on one metre square sheets of cotton. This gives me an idea of activity immediately above the sheets and will allow me to investigate dietary changes through the season. I am also in conversation with a pollen expert who would like to identify pollen in the droppings as a means of indicating foraging habitats. Diary Dates The next meeting will be the Christmas Social at 8:00pm on 10 th December at the Fighting Cocks, Horncastle. There will be an illustrated talk on the bats of Crete by Ian Nixon. The next open meeting will be on 14th January 2013 all members are welcome. BatLincs November 2012 Page 8