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Thursday, 8 September 2011

A Weekend With Engelbat

I once worked on a bat project with someone whose sense of humour was completely absent. Anyone who knows me will tell you that my sense of humour is ever-present and decidedly peculiar, so things would always be a little difficult! This person was adamant that individual bats should never be given names as it anthropomorphises them, though in my view giving something a name simply labels it and is harmless (it is poor interpretation of behaviour that anthropomorphises a wild animal). The result of this difference of opinion is that, in honour of the humourless one, any bat which passes through my hands is immediately given a ludicrous name. This is how Engelbat (Engelbat Humperdink? Geddit? No? See what I mean?) came to be named.

He was a juvenile Brown Long-eared Bat (Plecotus auritus), found one July morning on the ground floor of a large country house. The house has a known BLE maternity roost in the attic, four stories above, but Engelbat had wandered quite some distance from there and looked rather sorry for himself, covered in cobwebs and tucked under a radiator.

I had no way of knowing why he had left the roost. This site has no history of bats straying into the building. It's possible his mother had died, causing him to become dehydrated and leave the roost in search of water. However, as he was old enough to fly it is perhaps more likely that he got separated from his mother and simply ended up in the wrong place. I often explain to roost owners that young bats are just as likely to do something silly as young humans.

A close-up of Engelbat's wing, showing the clear patches (unossified bone) in his joints which indicate a juvenile.

I don't normally get involved in bat rehabilitation work. It's a difficult, skilled and phenomenally time-consuming job, so I normally pass casualty bats on to those dedicated individuals who excel in it (hats off to Tracey, Carol and Nigel!). However, Engelbat was a bit different in that he was several weeks old and capable of flight. he just needed some TLC and a plan to get him back into the company of his mother.

Having given him a drink of water (always the number one priority with a casualty bat - they can go a few days without food, but dehydration is a swift killer) I checked Engelbat over for signs of injury and found none. I then took him home and installed him in the bat-cage. This is simply a small plastic cage of the type used to transport hamsters etc. Inside is a shallow water-bowl, a glass jar of warm water with a towel wrapped round it (to simulate his mother) and a canvas pouch hanging on one site, to allow him to retreat out of site into a simulated crevice. He quickly grabbed onto the warm sock and settled down and I left him to get used to his new surroundings. Later he left the sock and took a drink from the bowl, before moving up into the canvas pouch: all positive signs.

Engelbat with the warm sock which acted as a mother/colony substitute.

A while later Isla and I got him out of the cage to feed and assess him. He had done a couple of droppings in the cage, indicating that his digestive system was functioning. When offered a mealworm he grabbed it with enthusiasm, but had some difficulty chewing it, a bit like a small child given a hard toffee. Mealworms are the standard food source for casualty bats, but for younger animals their tough outer skins are a bit too chewy. We tried him on "white" mealworms, i.e. those which have recently shed their skins and have not properly hardened. He found these easier, but still struggled, so from then on we fed him mostly mealworm innards. This is a delightful meal to prepare. First slice the head off a mealworm, then squeeze out its insides as though its a tube of toothpaste. The resulting blobs of vile gunk were voraciously devoured. He prove to be a slightly aggressive little bat, using his forearms to "stamp" at anyone who came too close. Male Brown Long-eareds have a reputation for being grumpy when handled and he fitted that stereotype quite well!

A brief video of Engelbat slowly munching his way through a white mealworm.
So far he ticked a lot of the boxes for being capable of rapid release: no injuries, functioning digestive system, eating and drinking well, so the final test was could he fly? He quickly demonstrated he could by flying happily round and round the living room. Brown Long-eareds are slow-flying bats, so the restricted space didn't seem to faze him at all and eventually he astonished us by managing to land and somehow grip a smooth painted wall, which I'd never seen a bat do before. Several more flights were managed with aplomb.

As he was clearly a competent flier for his age that led us towards how to restore him to his colony. Placing stray infants back into roosts is a questionable approach, as it is impossible to know whether the animals mother is still within the colony, or whether the juveniles wandering may be due to her death, for example killed by a predator. If this were the case then returning the juvenile to the roost may not be the best way forward.

After a conversation with Tracey Joliffe (a very experienced bat carer) for a second opinion, we took Engelbat back to the roost at sunset and placed him on a wooden bench which the adults fly over on their way to their feeding grounds. Our expectation was that his mother would encounter him and encourage him to fly with her. As it happened he chose to fly on his own and flew very competently along the flight line used by the colony, into the nearby woodland.

Of course it's impossible to tell the outcome of a casualty bat returned to the wild (unless you are Maggie Brown, who has done some amazing work tracking her casualties post-release, to evaluate their success). Hopefully he fed successfully and returned to the roost with the rest of the colony and hopefully he teamed up with his mother, if she was still alive. We'll never know for certain. Now I have to think up another ridiculous bat name, ready for the next bat who comes to stay...

If you're interested in caring for sick, injured or orphaned bats the best starting point is to speak to an existing bat carer, who can mentor you and help you get going. It's easy to get things wrong and sound advice and support is essential if you want to get it right. Contact your local bat group to find out who does bat care in your area. You can find your local group via the BCT website (and if you're not already a member...join!) . Another great source of information is the "Bat Rescue Manual", published by the West Yorkshire Bat Hospital, who also publish a regular newsletter: "Bat Care News". Your local bat carer will be able to put you in touch.

BCT Website: BCT Bat Groups page

My website David Dodds Ecology

Thursday, 18 August 2011

Anabats and Songmeters

I have written before about my good opinion of the Anabat SD1 (now replaced by the SD2, with some minor upgrades), a machine which offered huge advances in passive monitoring of bats (i.e. leaving a machine on site to continuously record bat calls), in use with a GPS receiver for walked and car transects (where a route is followed, recording bat calls and their locations) and for use as a training aid when connected to a PDA personal computer, to display live sonograms of bat calls. Prior to the arrival of the Anabat the only way of doing these surveys was with a Frequency Division bat detector, recording WAV (or poorer MP3) audio files: a massively time-consuming and data intensive process, so the Anabat was a big step forward.

Like all good things, the Anabat had some downsides: reliability has never been as good as it might be, technical support is patchy and confusing and the price (around £1400) is prohibitive for many users. So the arrival of the rival Songmeter SM2 on the UK market last year generated a lot of interest. At around £800 it is clearly cheaper and many bat workers and ecologists were excited to try out the latest generation of bat detector. Personally, I was quite cynical and, having had the chance to use several Songmeters this year, my reservations may have been justified. Let me clear though: I am not saying that the SM2 is not a good piece of equipment: it has a lot going for it. What I am saying is that, just like the Anabat, it has strengths and weaknesses and to claim as some have, that it is a technical advance on the Anabat is simply nonsense!

The two importers of the Songmeter, Alana Ecology and Envisage Wildcare have marketed the Songmeter powerfully in the U.K. and it's arrival on the market suggested that it was a new and exciting development. In fact the Songmeter had been on the market in the U.S., alongside the Anabat for quite some time. Anabat had been successfully sold in the U.K. by both companies for several years and both provided excellent technical support. In early 2010 Titley Electronics (who make the Anabat) suddenly withdrew the product from them and set up a European sales office in the U.K. Deprived of a key part of their product ranges, both companies looked around for a replacement product and settled on the Songmeter. So it's arrival here was a result of commercial necessity, rather than technical development and the flurry of interest in it is primarily a result of marketing hype. So I was interested to get my hands on some Songmeters this year and find out how they match up to the hype.

An Anabat SD1. The later SD2 version has a USB socket on the right-hand side, rather than a serial port. The velcro on the left was stuck on to allow a GPS receiver to be attached for transect work.

A key advantage of the Anabat is the fact that it converts bat call audio to a digital format, so that each bat pass generates a tiny file of around 2-5KB. Thus a 2GB memory card can last weeks or even months, without needing to be replaced. The SM2 records WAV high quality audio, compressed to form WAC files. Theoretically, this allows the creation of better quality sonograms for analysis. Unfortunately, the compression results in very large files, compared to Anabat. My experience of using SM2 has been of long hours spent downloading, copying and converting many tens of Gigabytes of data. The Songscope software supplied by Wildlife Acoustics (the makers of Songmeter) is expensive and unpopular, so that most people use Analook (the Anabat software) to analyse Songmeter data. Wildlife Acoustics supply a free program (WAC2WAV) which converts WAC files to ZCA format, so they can be analysed using Analook. However, running WAC2WAV on large amounts of data (and most passive monitoring produces large amounts of data) is slow and tiresome.

Using Anabats for passive monitoring has always created the problem of waterproofing, leading to many imaginative ways of keeping Anabats dry and free from condensation when used in the field. Unfortunately, long-term use in our wet Scottish climate has always been a problem, with inevitable condensation build-up leading to failure if the machines aren't occasionally taken somwhere warm, to dry out for a few days. The SM2 case is waterproof in itself and needs no further protection. It also addresses the Anabat problems by including "Humisorb" pouches inside the units and having a valve to equalise air pressure inside with that outside. That sounds ideal and would be...if it worked. At present several of the SM2s I am using have proved unequal to the challenge of a cold, wet upland site, with quantities of condensation present inside the machines. In fairness, none has yet stopped working and the manufacturers have proved keen to find a solution. Only time will tell if they are successful.

There is a clear cost benefit in buying an SM2, rather than an Anabat, but there are also hidden costs. A 2GB CF card for an Anabat costs around £15, but a set of four 32GB SD cards for an SM2 could set you back several hundred pounds (how many you need will depend on how often you download data). SM2s have internal capacity for a set of outdated D size batteries. The machines reportedly do not respond well to the lower voltage produced by rechargeable batteries. Happily the machine, like the Anabat, will work with an external Sealed Lead Acid Battery. Unlike the Anabat, you will have to pay around £100 for an external voltage regualator. Oh, and if you want the software designed to be used with the Songmeter, that will be another £500.

Probably my biggest beef with Songmeter is its lack of flexibility. It is a passive monitoring machine. Full stop. Anabat has a range of potential uses, as I described above. The SM2 does have some interesting potential though. For example, it comes with an in-built temperature recording unit. It also has the ability to work with two separate microphones concurrently. Potentially, this allows some interesting studies to be carried out, using extension microphone cables. For example, recording the direction of bat movement along a linear feature such as a hedgerow or comparative studies of bat activity at ground level and at height.

A Songmeter SM2 in position, attached to a post. This unit is being operated with two microphones simultaneously.

Another intersting feature of the Songmeter is it's omnidirectional microphones, which pick up bats in all directions. This is potentially a useful feature in a passive monitoring machine. When a detector is used in the hand we tend to point it at bats we hear, getting the clearest possible calls. When a detector is used passively the directionality of the microphone works against us, so an omnidirectional microphone seems a good idea. However, it has drawbacks too. A microphone which picks up bat calls in all directions also picks up background noise from all directions too, reducing the gap between noise and bat calls. This could easily reduce the clarity of a recording and increase the number of non-bat ultrasound recordings.

My biggest beef with the Anabat has always been it's limited ability to keep accurate time. Over a period of weeks they are fine, but over protracted periods of use the internal clocks tend to lose or gain time. So far the SM2s I have been using have been reliable in that respect. They also have a useful ability to be set to start and stop recording at specified periods before sunset/after dawn, rather than specified start/finish times, as with the Anabat. This saves having to reprogram them through the year, to reflect changing dawn and sunset times.

One colleague I spoke to this year was hopeful that using SM2s intead of Anabats might reduce the number of equipment failures. Sadly that hasn't been my experience. It's easy to think that, when you buy a machine with a high price tag you are getting high quality electronics, but electronic development doesn't really work that way. The major cost in producing any electronic equipment is the initial development cost. If you are developing a new iPod, confidently expecting to sell millions of units, you can afford to invest millions of pounds in perfecting the design. If you are developing a bat detector, with an expected sale of a few thousand units then the development budget is inevitably much smaller. In this respect both machines are in the same boat and they appear to have an equal propensity to fail.

So what would I spend my cash on? Well, the SM2 is an interesting piece of equipment, with some useful features. It had the potential to knock the Anabat for six on waterproofing and reliability, but so far it has proved no better on either score. It lacks the Anabat's flexibility and it's memory-hungry format is time-consuming to manage. So, unless I was involved in a project which could benefit from the specific extra capabilities of the Songmeter I would spend my hard-earned cash on an Anabat.

Wildlife Acoustics (maker of the Songmeter)

Titley Electronics (maker of the Anabat)

Wildcare & Alana (the UK Songmeter importers)

My website:

Thursday, 10 March 2011

Realities of bat conservation in Malta

As a wildlife conservationist with an especial interest in bats, I sometimes despair of the state of conservation in Britain and the prospects for the future of biodiversity. Cut-backs in conservation spending, prioritisation of projects that engage people, rather than those with real impact, the near-impossible task of enforcing wildlife law are all sources of frustration. Whilst these problems are all very real, they were put in context for me last year, when I spent some time working with bats on the Maltese Islands.
Malta is of course, part of the European Union and therefore bats and their roosts have the same legal protection, as elsewhere in Europe. However, Malta is a small country and pressures on wildlife are magnified by problems of scale, as well as by social issues.
I was lucky enough to spend time with Dr. John Borg, Director of the Malta Natural History Museum in Mdina. John is an energetic and ornithologist and bat-worker, who faces monumental difficulties and yet still works relentlessly to promote conservation. Malta, like several other Mediterranean islands, has a strong culture of shooting and trapping migratory birds. Though now curbed by European legislation, this is still a very real problem in Malta and it affects bats too, as they are used for target practice as they emerge from the roosts at sunset.
John Borg with a Maghrebian Mouse-eared Bat
When I was there the sound of gunfire was a constant backdrop, away from the towns. Hunters take their shooting heritage very seriously and John's work as a bird-ringer has brought him into conflict with them. Whatever our problems in the UK, we don't face the kind of intimidation John faces. He has had his car set alight, his tyres slashed and lights smashed and has even had a hole punched in the driver's door by a shotgun blast! To emphasise the point, when we were leaving a bat cave we had to leave quickly, as the trees above our heads were shredded by apparently deliberate shotgun fire.
A typical Maltese bird-shooter's hide. The island is littered with these structures.
The small size of the islands and their growing population creates massive development pressure, and the Maltese Environmental Protection Agency (MEPA) are very active in enforcing the law. Nonetheless, bat roosts are heavily pressured, especially underground sites, as the size of the islands makes the limestone caves used by Maghrebian Mouse-eared Bats (Myotis punicus), Grey Long-eared bats (Plecotus auritus) and Lesser Horseshoe Bats (Hipposideros hipposideros) often well-known and threatened by human activity.
I visited two of the biggest maternity colonies of Maghrebian Mouse-eareds, neither of which showed any signs of being used by the species any longer. Ghar Hasan is an extensive cave on the cliffs at the south east coast of Malta. It is a popular attraction and, as well as being visited by tourists, the litter within showed it is also used by the seedier end of humanity. In order to protect the bat colony, John Borg paid for a gate to be installed on the section of the cave used by the bats. When we visited part of the gate had been ripped away. John showed me where, in previous years there had been a large heap of bat droppings. Now there is nothing.
The vandalised bat gate at Ghar Hasan
Another formerly prolific maternity cave was Ghar il-Friefet, on the outskirts of the town of Birzebugga. When a new road was built over the cave attempts were made to safeguard the bats by gating it. Today this gate lies alongside a hairdresser's salon and the cave is no longer used by bats. The road surface was less than three metres above the cave roof and John described how the bats would take flight every time a truck drove overhead.
The bat gate at Ghar il-friefet - sadly a lost cause.
I wouldn't want to leave you with the impression that wildlife conservation is a lost cause in Malta. Alongside John's efforts, Birdlife Malta are an extremely active conservation organisation, who are making a real impact. Also, MEPA have a deliciously hands-on approach to dealing with planning violations (often the hands are on the controls of a bulldozer), from which our SNCOs and local authorities could learn a lot.
One of the most poignant moments of my visit to the island was when I spent some time with a group of undergraduates at the University of Malta, teaching them how to use bat detectors. Their enthusiasm and commitment to wildlife conservation was little short of inspiring and if they are the future of Maltese wildlife conservation the game ain't over yet.
Discussing bat detectors with a group of students from the University of Malta - the bright future of Maltese conservation

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Swarming bats and shivering bat workers

Last September I spent a night outside a disused lead mine, with fellow bat-workers from Lothians Bat Group and Dumfries and Galloway Bat Group. Our goal was to find out whether any autumn swarming activity took place and to catch any swarming bats and examine them for ectoparasites. As a licensed trainer I would also use this as a opportunity for bat license trainees to gain some experience handling bats.
The site was high in the hills of Dumfriesshire and as the sun went down it was a beautiful, calm evening. The mine had two access points: a ventilator on the hill above us and an addit (a horizontal shaft) leading into the mine. We blocked the ventilator with rubble netting, to ensure that any bats inside the mine would leave by the main entrance and set up my harp trap across the addit (see "The Kitchen Table Harp Trap", Feb. 2008 and "Happy Harp Trapping", August 2008).
The harp trap in place across the mine entrance, with rubble netting at the sides and below, to prevent bats from flying round the trap.
Our hope was to find that the mine might be used by Myotis bats (which in Scotland means Daubenton's, Natterer's and Whiskered) as a swarming site. It has suitable characteristics to be used as a winter hibernaculum and swarming bats had been recorded there the previous autumn. Myotis bats tend to gather in the middle of the night during August, September and October and fly together. It's not clear why they do this, but mating is probably involved, as males tend to remain around the sites and females commute in from surrounding areas. It may also be connected with checking access to a hibernaculum or showing the site to juveniles. John Altringham's team at Leeds University have been researching this for some time, revealing some fascinating insights (see "Untold riches of swarming bats", April 2008).
Soon after sunset a bat flew into the trap from within the mine. It was an adult male Daubenton's Bat (Myotis daubentonii). Sadly (for me, not the bat) it had no ectoparasites, but provided good handling experience for two trainees. This was fortunate as it turned out to be the only bat that we caught...
The adult male Daubenton's Bat we caught, before the temperature dropped.
As autumn swarming is an all-night activity we started the evening sitting around in folding chairs, for all the world like a group of picnickers, with positive thoughts about spending the entire night there. Then it started to get colder....and colder. Soon it seemed like a good idea to erect the gazebo someone had brought. Then we added the side walls. Then the sleeping bags and blankets came out!
Dr Stuart Smith demonstrates the right equipment for bat-work in sub-zero temperatures.
Common sense told us we should give up. After all, with the thermometer at just 2 degrees there wouldn't be any bat activity would there? Actually, yes there was. Two bats had been swarming around the front of the mine fairly continuously since not long after the Daubenton's was caught and released, but were not tempted into the trap. From the bat detector we could see they were Myotis and their relatively faint calls made me suspect they may be Natterer's Bats (Myotis nattereri), but without catching them we couldn't be sure. Possibly they were males, awaiting females arriving from elsewhere. If so then they were destined to be were we!
Eventually, after many hours, when the thermometer descended below zero we concluded that the female bats had more sense than us, or the males, and had stayed home! We packed up and followed their lead. The next day I tuned in to the TV weather forecast in time to hear the forecaster say that the previous night was "the coldest September night for decades".

Important note: In the UK (and other European countries) it is a criminal offence to catch, handle or disturb bats without a license issued by the relevant SNCO (Scottish Natural Heritage, Natural England etc).

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