Plecotus

The Annual Journal of the N. Yorkshire Bat Group
Issue 1 - 1999

Contents

Introduction
VIIIth European Bat Research Symposium
BCT National Bat Conference
Bats and farm woodlands
How many batworkers does it take to find a bat?

Introduction

Welcome to the first edition of what we hope will become an annual publication from the North Yorkshire Bat Group. Within these pages you will find articles and reports about bats from both home and abroad, plus distribution maps of each of our North Yorkshire species.

Comments on this edition will be most welcome, as will contributions to the next edition, due out in Autumn 2000.

John Drewett
Chairman


VIIIth European Bat Research Symposium - Kraków, Poland 23-27 August 1999
by John Drewett

In August, batworkers from nations stretching across Europe from Ireland to Ukraine gathered in the historic city of Kraków to discuss the latest research into the world of bats. As well as the opportunity to meet old friends, there was the welcome chance to make new contacts, especially with delegates from eastern Europe and to view dozens of poster displays describing the vast array of bat work currently underway across the continent.

With almost 150 papers and posters presented, there is insufficient space here to give even a brief summary of the complete proceedings, so what follows is a personal account of what I think may be the most interesting highlights seen from a North Yorkshire perspective.

In 1998 the French Mammal Society (SFEPM) began a project to update the Atlas of French Mammals, starting with bats. A mapping project was quickly initiated for the nation's 30 species with the intention of completing the project by 2002, presumably in time for the next research symposium which will be held in Le Havre.

A German paper looked at the provisions which can be made to accommodate bat flight paths into the design of new motorways. A range of schemes are being tried, but as this is a relatively new area, the effectiveness of these measures has yet to be confirmed.

The activity of a colony of Brown long-eared bats has been studied with the aid of a remote infra-red video recording system. This has shown flight activity within the roost takes place throughout the day and that during parturition and until the juveniles could fly, bats made greater use of a crèche area adjacent to the chimney, which was 3-8 degrees Celsius warmer than the roof apex.

There has been some suggestion that the only way of accurately ageing small bats is to count the dental incremental lines on their teeth. However, work in Lithuania casts doubt on the validity of this method, particularly where bats are more than ten years old.

While North Yorkshire has a couple of known Noctule roosts which are not in trees, we probably would not consider this a particularly adaptable species. Yet, in Hungary, the Noctule's adaptability ensures that it is the commonest species of bat. There, Noctule bats roost in cracks in the walls of tower blocks in large towns. They seem to prefer west facing roosts, 6-8 m from the ground where they can be found in vast numbers. In one 81 ha study area there were 148 roosts, with a density of 83 bats per ha. The location of roosts appears to be independent of the quality or quantity of surrounding vegetation. Noctules also roost extensively in similar locations in the Czech Republic. In winter this species hibernates in buildings in a range of countries including Sweden, Holland, Croatia, Ukraine and Kazakhstan.

Radio-tracking in south Wales has revealed that Lesser horseshoe bats are more active around woodland, with hedgerows and riparian habitats also being particularly important. Some animals were observed foraging in tree canopies up to 2.5 km from their maternity roosts.

The Greater mouse-eared bat (Myotis myotis) is found on both sides of the Gibraltar Strait, yet genetic investigations have revealed no connection between the two populations. For a species that can travel hundreds of kilometres, it is odd that they do not cross the 17 km strait. It is now considered that the Moroccan bats are a distinct species which will probably eventually be named Myotis omari.

In Britain, where the Greater mouse-eared bat is now extinct, we can only be envious of Christian Drescher working in Gargazon in northern Italy where he is studying the diet of a colony of 1300 adult females roosting in the village church. The surrounding landscape is intensively cultivated, but the bats actively hunt in the orchards. Analysis of droppings found they fed on 15 taxa, but particularly on mole crickets and carabid beetles.

Work on Natterer's bats in Germany and Switzerland has found that the animals mostly hunt individually on summer evenings, but that their foraging ranges overlap. They preferred feeding in orchards and along forest edges and had an average home range of 31 ha.

The calls of Greater horseshoe bats consist of a long constant frequency (CF) component with a short terminal FM (tFM) component. The tFM part of the call is used to localise targets while the CF part is considered to play the major part in actually detecting fluttering insects. However, work with trained captive bats in Germany suggests that this species also uses the CF component to guide it along regular flight paths and also to warn the bats of unexpected obstacles.

Whereas much bat conservation work involves persuading people not to do things that will endanger colonies, in Ireland the Vincent Wildlife Trust takes a more positive approach to the conservation of Lesser horseshoes. They have leased or purchased a number of buildings which were becoming dilapidated and undertaken extensive repairs, so far to the benefit of about 1000 bats.

An excellent example of what an amateur can achieve is Dave Priddis' work on horseshoe bats in the Lower Wye Valley on the English/Welsh border. Within the study area 200 sites used by horseshoe bats and a further 100 potential sites have been identified. The area contains 18% of the UK Lesser horseshoe population and 6% of the Greater horseshoe population.

Their size and habits make it difficult to assess the number of bats killed by motor vehicles. Peter Twisk from The Netherlands has looked at evidence collected from dead bats found during bicycle rides in Europe and the results of a systematic survey by W Jongejan in central Netherlands to estimate that 0.7 - 1.4% of all Dutch bats are killed annually by road traffic.

BCT National Bat Conference - Ripon 10 - 12 September 1999
by John Drewett

Coming shortly after the Kraków conference, there was something of an overload of information for those of us attending both events, although this was relieved to some extent by some speakers presenting the same paper at both conferences. Even so, there was too much new information to adequately summarise here, so these are again edited highlights.

The conference began with a look at the wide ranging work of Bat Conservation International, a clearly well financed organisation. Next, at the other extreme, was a well presented paper by Sergiu Andreev, the bat worker of Moldova, on his country's bats. It was good to see him leave the conference with a selection of equipment thanks to the generosity of sponsors and those supporting the conference raffle. John Altringham from Leeds University ended this session with a report on the bats of the Brandberg mountain in the Namib desert.

The ecology and behaviour session covered the rare species, Bechstein's, Barabastelles and Horseshoes. Woodland and wetland play an important part in the requirements of female Bechstein's while Barbastelles in West Sussex seem to have exclusive hunting ranges within the total colony range area. In Norfolk, the Barbastelles were initially feeding around a wooded churchyard and garden, before moving later in the evening to feed over vegetated sea cliffs and along the beach.

Many other fascinating papers were presented, including one from Noel Jackson of the Durham Bat Group. His group has been developing guidelines for local planning authorities in an attempt to place some structure on the process by which bats are considered in planning applications. The scheme developed is thought to be effective in highlighting the presence of most species other than the pipistrelles. Since the conference both the North Yorkshire Bat Group and some academics are working on further refinements to this scheme with the hope that it can be more widely implemented.

As usual, the conference included a range of workshops covering useful topics such as the effective use of bat detectors, bats in bridges, planning the work of your bat group and ageing, sexing and handling of bats. This year there was also a very useful post-conference workshop on the use of time expansion detectors. It was encouraging that each of the field sites suggested by our group for the bridges and time expansion workshops proved to still support bats despite our data not having been updated for more than a decade.

Bats and farm woodlands
by Niall Moore, Central Science Laboratory

Since 1988, the Ministry of Agriculture, Fisheries and Food (MAFF) has been encouraging farmers to plant woodlands on farms by providing money under two schemes, viz. the Farm Woodland Scheme and the Farm Woodland Premium Scheme. To date, almost 70,000 hectares has been planted or approved in the UK in the 11 years of the schemes. Most of these woodland blocks are small (several hectares) and predominantly broadleaved (almost 90% of the trees planted in England). Although originally the rationale behind the schemes was reduction of farm surpluses, MAFF is also anxious to maximise the environmental benefits of these plantings and has commissioned several research projects on aspects of biodiversity in small farm woodlands. CSL (an agency of MAFF) is carrying out research on bats to attempt to identify ways in which these new plantings can be designed to maximise the benefits to bats.

Our initial work was carried out in Suffolk in summer 1997 where we carried out detector surveys on 45 plantations. We have been using Pettersson bat detectors with time expansion which allows analysis of calls back in the laboratory. This work showed (to our delight) that bats of several species (Pipistrelles, Noctules, Myotis species and Serotines) were making extensive use of these plantations. Most of the plantations are small (less than 2 hectares) but all still had some bat activity. Bats were more attracted to plantations that were larger, weedier and closer to existing woodland. They were feeding more over plantations with taller trees. In 1998 we decided to move the focus of the work to the Vale of York and carried out a more extensive detector survey. Once again, bats were making use of all the plantations but the factors influencing usage were not always the same as those that were identified as important in the previous year. Similar species were identified to those in Suffolk with the exception of the lack of Serotines in Yorkshire. We did find 45 kHz Pipistrelles at virtually all of the plantations, Noctules at most and Myotis bats at over half on at least one of the six visits. 55kHz Pipistrelles turned up at over 30% of sites too.

Work is continuing this year with efforts concentrating on radio-tracking as well as detector surveys. We have thus far attached radio tags to two brown long-eared bats (one male and the other a non-lactating female). This species is supposed to forage almost exclusively within 1km of the roost. In our naiveté we thought that following the bats (all night!) would be easy as the transmitters had a range of 1km. Unfortunately (but interest-ingly) the male was trekking 2-3kms every night to feed, despite an abundance of suitable woodlands close to the roost. The female, however, was more elusive and we lost contact with her every night as she disappeared in a southerly direction. The rest of the night was spent fruitlessly searching for her. On the ninth night of her disappearance we found her foraging nearly 7kms from the roost! That same night the tag fell off back at the roost. We now intend to tag some lactating females to see where these forage. We are also investigating if bats have preferences for individual tree species by placing automatic recorders under trees in hedgerows.

The end product of all this research will mean that MAFF will be able to make more informed decisions with regard to new woodland plantings, tweaking the grants to produce more bat-friendly woodlands. With the substantial contribution that new farm woodland plantings are making to woodlands on farms, this should help reverse the huge losses of suitable bat habitat caused by agricultural intensification. This is especially pertinent in arable areas, precisely where the farm woodland schemes are targeted.

How many batworkers does it take to find a bat?
by John Drewett

In the previous article Niall Moore describes the research being carried out by the Central Science Laboratory into the activities of Brown long-eared bats in the Derwent valley just into East Yorkshire. Sounds easy, doesn't it? However, anyone who has ever worked with animals will know that things are seldom that straightforward. So it was that the assembled expertise of the North and East Yorkshire Bat Groups, Bat Conservation Trust (BCT), Central Science Laboratory (CSL) and several other bat workers assembled outside a Yorkshire farmhouse one July afternoon in 1999 to catch and radio-tag some Brown long-eared bats.

We all knew that the house was an established roost, the owners were co-operative and access to the roof space was relatively easy. So what could possibly go wrong?

After brief discussions, Tony Hutson from BCT and myself agreed to climb into the roof with our nets and cloth bags to collect the bats and bring them out to the assembled party for weighing, recording and tagging. After half an hour we emerged through the hatch, climbed down the ladder and out into the garden much dirtier, only to admit that we couldn't find any bats.

Never mind, we still had plan B. The bats must be somewhere in the building, so all we had to do was to string up a few mist nets around the garden, retreat to the pub, then return at dusk to remove the bats from the nets, tag them and release them. Of course, the bats had other ideas. One volunteer bravely clung to the top of a long ladder for much of the evening holding a static hand net over a supposed emergence hole, only to see a bat appear from somewhere out of reach. Otherwise the evening was fairly uneventful.

Batworkers are not easily deterred, so next morning saw us back at the house for another assault on the roof. This time we did find a bat - yes, just one. He was tightly wedged into the roof apex against a beam, but with some persuasion was encouraged to submit himself to the indignity of being tagged.

After this bat was returned to the roost and we decided to check on another Brown long-eared roost in a house a few miles away, just in case we had better luck there. After negotiating a rickety ladder and climb through the hatch which was concealed in a small cupboard, we were astounded to find around 80 long-eareds hanging from the beams and flying round the roof space, many with babies attached. So as to minimise disturbance, we quickly collected a selection of bats and retreated outside to check their weight and condition. A non-lactating female was chosen for tagging and the rest returned to the attic. Success at last!

A few days later I was chatting to Niall when he told me how this female had been found foraging 7km away the previous night. This sounded like an interesting bat to follow, so I volunteered to spend the next night in the field with Niall tracking her. At the appointed hour we met near the farm and soon picked up the tell-tale bleep on the receiver which suggested she was still in the roost. We moved down the track to the farm and stood waiting outside the house for her to emerge, ready to make a dash after her as soon as she left the roost. An hour passed and she still hadn't moved. Then another hour. And another. Eventually, in the middle of the night we got bored and went home. Had her long excursion the previous night tired her out? Had she died in the roost? Or had something else happened?

The next night another observer bravely (foolishly?) waited for her to emerge, again to no avail. The time had come to find out what had happened. Next day we decided to check out the roof space. The bats were still there and we could clearly pick up the signal from the tag. Eventually we found the tag wedged between a couple of roof tiles, no longer attached to a bat! It seems that on her return after her long expedition, as she had squeezed through this tiny gap the tag, which was simply glued to her back, had become detached.

Despite the set-backs this small project has already provided valuable information about these bats and will no doubt have taught us some valuable lessons for more tagging in the summer of 2000.