Monday 27 October 2008

National Bat Conference; 2.

2. Bat rehabilitation – why bother?

Gail Armstrong of the North Lancashire Bat Group gave a presentation at the Conference on care and rehabilitation for bats. She had collated data from years of taking in grounded bats and trying to release them back to the wild. She concluded that statistically it did not appear to make much sense in trying to release the bats. Many of them were cat attacked and were unable to be kept alive let alone nursed back to health. But it wasn’t the small number of bats that were released that was the most important. Very few of her bats were able to be released and the potential impact upon populations is hard to determine, but is likely only to be small. Any help though is better than none.

The biggest impact of taking in grounded bats though seems to be the communication of details about bats to members of the public. The majority of members of the public never come into contact with a bat and many still seem to have the idea that they are some form of rodent that will damage their house and stop them using it if they decide to roost their. But, collecting grounded bats from the public is an ideal time to talk to them about what bats are and how they live. Being able to show someone how small and in offensive a bat is a wonderful piece of bat conservation.

And it’s true. So many times I have collected bats from people who have found a bat in their house or garden and not known what to do. Hopefully, after seeing the bat at first hand and being shown by someone how fascinating bats are they will have a better understanding of why bat conservation is important and how they can help.

Monday 20 October 2008

National Bat Conference.

National Bat Conference.

1. Lesser Horseshoe bats and buildings.
The National Bat Conference was held at Reading University this year. One of the talks was by Henry Schofield of the Vincent Wildlife Trust. The Trust have over may years purchased properties and adapted them as roosts for Horseshoe Bats, particularly Lesser Horseshoes. The talk was a brief introduction to the types of buildings they had adapted and the styles of new bat roosts that had been built. The new buildings were built to look as much like small agricultural buildings or houses as possible. Having undertaken the creation of new roosts over many years the Trust had built up an extensive knowledge of what worked and what didn’t.

They had monitored the types of materials used and which worked best, creating hot and cool areas within roof spaces for the bats to use at different times and tried different methods of ensuring bat access but deterring use by birds etc. The amount of information available upon what worked for Lesser Horseshoe bats was wonderful and the talk was ended by promoting a book that the Trust was releasing about the work they had done over the years. The information provided will be invaluable for work with Horseshoe bats but will also help to plan mitigation for other bat species by guiding people what materials are good and what should be avoided.

The book comes out in late October but I’ve already ordered a copy.

Friday 17 October 2008

Boys and their toys.

In September and October male bats will be spending time feeding ready for the winter and hibernation, but they will also be trying to attract females to their harem. Male Common Pipistrelle bats add 'chonking' sounds to their echolocation, associated with mating. The most succesful males will gather bigger harems of female during this period.



When going out with a hetrodyne bat detector it is possible to hear these 'chonking' sounds. By recording the ultrasound calls through a frequency division or time expansion bat detector it is possible to analyse the sound on a computer. I have recently been recording Common Pipistrelle bats at a roost with a Batbox Duet frequency division bat detector. This detector analyses all of the ultrasound and divides the frequency by 10 in order to make it audible. The information can then be put into a program, I use batscan, to produce a a sonogram, a graph of the sound frquencies of the call.

This call shows the lower frequency 'chonk' sounds that the bat is making, as well as the normal echolocation calls.

Monday 13 October 2008

Releasing bats, again.

I’d collected a bat from a school. It had apparently flown into an office and was picked up and put into a box with some shredded paper. By the time I arrived the milk bottle top in the box had been spilt and the bat was soaked. Taking out one very bedraggled and sorry looking bat I showed all of the staff how small bats really are.

I was on my way back home with the kids so they all came in to help. Having seen plenty of bats before they were not phased by any of it. When we got the bat home I had another look at him and checked him out in more detail to make sure there was not damage. Because he was soaked and looked very small I did not have too much hope for him but we dried him off and put him into a larger box with space to hang and fresh water. A little later I took him out and the kids helped me feed him mealworms. They helped by chopping off the head and gently rubbing the mealworm around the bats mouth so that it got the taste and smell.

Sure enough in a few minutes we had him eating mealworms. Over the next day or so he began to take meal worms from a bowl that we just topped up a couple of times a day. Within a few days he was eating happily and had put enough weight on to allow him to be released. With the kids we went to the school and stood on the grass outside one evening when the weather was good, and the forecast wasn’t for rain for a couple of days. A miracle in that part of September! With gloves on the kids held the bat and warmed him up, feeling him begin to shiver and warm him self up. After about ten minutes Rose said that he was getting very wriggly. I told her to open her hand more and let him crawl up the glove to the edge of her hand. To everyone’s delight he spread his wings and dropped off her hand, flying off. He flew around in circles for a few minutes and then he was off.

The kids really enjoy telling their friends about helping the bats. Not everyday in most peoples households! All good publicity for bats and bat conservation.

Friday 10 October 2008

What are bats doing now?

As the weather begins to get colder in October insects become fewer. All British bats eat insects and therefore their prey/foodstuffs become less.

Bats can handle the colder weather because of the fur on their bodies and because they are mammals. But there will come a point when the energy expended in catching insects is greater than that available from the insects that are around. At this point the bats will decide it is better to stay in their roost and slow their body down, go into torpor.

In the cold of winter bats will hibernate, but before they get to this point they have to eat as much as possible in order to put weight on ready for hibernation. So slowing their body down in torpor is like a mini version of hibernating. They use very little energy/fat and can last long terms between feeds as the weather gets colder and the insects become fewer.

Monday 6 October 2008

Bats don't have back bones - do they?

We went to collect some grounded bats that had appeared in an office at a hospital. The call had come because there were 15 bats in the office when someone entered the office in the morning. They opened a window and locked the room. When we got there to rescue them there were only 6 hanging on the curtains, the others presumably having flown out of the window.

As usual with these things everyone wanted to see the bats and be told about them. One gentleman who was dressed in what appeared to theatre overalls was very animated about looking for bats. He was clearly interested in wildlife and had seen bats at some point. He did however let himself down by saying that ‘bats don’t have back bones, do they?’ Quite where he’d got the idea from we never knew but he was convinced that bats did not have a back bone. How else could they crawl into such small spaces!

We had to explain that the majority of the bat that you see is fur and that the body underneath is really very small. This is the reason they can get into such small spaces, not the ability to be a slug! People get the strangest ideas.

The bats were taken back that night and released. Hopefully they won’t return to the hospital.

Thursday 4 September 2008

Light levels.

It seems to have been wet for ever. Not the extreme weather of last year. Just continuously wet and damp.

Bat surveys can’t be done in the wet and bats can’t forage. I did one bat survey, arriving on site fifteen minutes before sunset, and there were Common Pipistrelles already feeding amongst the trees at the end of the garden. It had rained for a couple of days before so the bats were hungry. The evening was overcast, so the light level was low. Hungry bats had therefore come out earlier than usual. Braving the possibility of being picked off by birds of prey, in order to get fed!

The books say that Pipistrelles will come out about fifteen to twenty minutes after sunset. But, should we rather being saying that bats will come out at certain light levels?

Bats don’t watch the clock. They don’t read the books about what they are supposed to be doing. They must have some sort of sense about when the light level is right for them to go out, and not be liable to be someone else’s dinner. So, should we be measuring the light levels when the first bats emerge?

A talk with another bat worker who understands technology better than I do led to an idea that you could use the old style light meters used with 35mm cameras, and available second hand. The light levels on the meter should be able to be correlated to light levels measured in Lux from a light meter. This would allow light levels to be measured in a standard unit that could be used any where. Measurements could then be compared between sites and at different times of the year to see if there are any patterns about emergence.

Tuesday 2 September 2008

Releasing a bat.

Being on the care and rehabilitation list for the region brings you calls at all sorts of odd times and for places you’ve never been. A month ago I received a call that someone had found a bat on the path outside their office. The office was only just down the road, so I called in and collected the bat. It was a juvenile Common Pipistrelle that appeared quite healthy. No wing damage. No wounds. So probably not cat damaged, which is always a relief when collecting a grounded bat!

Handing it on to someone who is better organised and more skilled at looking after bats is something you have to do when you have four children. The same day I collected another Common Pipistrelle from about a quarter of a mile away, so a busy day!

Last night I took the first bat to release her. The lady who had found her wanted to see her released. She had become fascinated by bats after being told their life cycle and shown the grounded bat when I collected her.

The bat had put on weight and had been to the flight cage to show everyone she could fly. I’d had her for two days, feeding her on meal worms. The evening was overcast but warm. I held the bat in my hand for a few minutes while the lady who had found it and I talked about bats. The bat warmed up nicely and began to get active in my hand, trying to escape. So, it was time to release her. And off she flew, into the distance and off into the dark.

The other bat still isn’t flying but hopefully it will. The big plus though is getting people to be involved in bat conservation. Seeing other people get as enthusiastic as any other batty person and want to support bat conservation in any way they can.

Saturday 30 August 2008

Bats sometimes change roosts!

There is a building on a site that we have obtained planning permission and a European Protected Species licence to demolish. There had been a single Common Pipistrelle in there last year and we had designed and constructed new roosting opportunities on site for the Common Pips using the building. The bats were roosting between the underfelt and the large interlocking concrete roof tiles. Access was through a gap in the verge where the concrete had fallen out at the junction between the roof tiles and the ridge tile.

The demolition, originally scheduled for the early part of 2008, was put on hold because of funding issues, so the building was put into the monitoring programme for this year. It was quite a surprise therefore to find 11 bats emerging during mid July from the same spot. The bat detectors showed that they were all Common Pipistrelles. Because of the possibility of them being part of maternity roost we thought it best not to hand net them until late August, when the juveniles would all be flying.

So, there we were last night on the roof waiting for the bats. The building has two adjoining pitched roofs with a large, 1.5 metre wide, valley gutter between them. Plenty of space when we’d got up on the roof to move around safely. Luckily the interlocking tiles are all laid on a shallow pitch so it was possible to walk up the tiles and lie down close to the ridge. I could then hold the hand net just below the entrance to the roost without getting too close myself. It was much easier than trying to hold a hand net in place from the ground. With 5 metres of extensions on to reach the ridge hand nets soon get very heavy, and they also wobble a lot, putting off bats they may be waiting to emerge.

The weather was good. 16 degrees Centigrade, light winds and overcast, but dry. A perfect night to find out more about the bats in the roost. It was still a good night an hour and a quarter later when I was still lying on the roof and Anna was listening to a Noctule and Common Pipistrelles on the bat detector, but no bats had emerged. All the preparation and the bats had moved on!

Friday 29 August 2008

Swarming bats.

A return to site for a dawn survey to find out if the bats are returning to roosts in the building being surveyed sounds great until the alarm goes off at 03.50. It is even harder to drag yourself out of bed if you only got back from an evening bat survey at 22.30.

One of the wonderful sights of dawn surveys is of groups of bats ‘swarming’ around before they enter their roost. This morning was slightly different. From 04.30 there were a few Common Pipistrelle bats flying past the building, continuing to feed, and a few Natterer’s bats feeding around a two storey entrance to an open section of the barn. From 04.52 the Natterer’s bats increased in number until there were seven ‘swarming’ around the entrance to the barn at one point. The bats circled around the entrance to the barn before flying inside and then flying around inside the building. This included flying around in the roof space and flying into the open first floor storage areas.

The bats continued to fly in and out of the barn until around 05.30. Standing in the entrance to the barn I had counted 26 bats entering but only 22 leaving. There are other entrances to the barn so they may have exited elsewhere or it may be that some remained, roosting in the cavities in brickwork and splits in the beams that can be found throughout the building.

I’ll have to return to site with the night shoot video recorder for another dawn survey to film the ‘swarming’ and try and take some of the Trainee Volunteer Bat workers along to practice with their bat detectors and to see ‘swarming’ bats.

Thursday 28 August 2008

Evening emergence surveys.

I was surveying a set of buildings last night. Building surveys had found evidence of bats using the building. This had included droppings, individual and in small clusters, as well as butterfly wings. The butterfly wings indicated that bats may have been returning to the building to perch and eat some of their larger prey. In order to gather further evidence on the species and numbers of bats I initially arranged to visit the site and undertake an emergence survey.

Bats emerge in the evening to catch insects. Some species emerge around dusk, while others wait until it is nearly fully dark. Standing outside a building from just before sunset you can see any bats that roost in the building emerging. As it gets darker this becomes more difficult and the use of aids such as night vision binoculars or night shoot video recorders can help. The best aid to finding where bats are roosting, where they are going to eat and what species they are is a bat detector. One type of bat detector commonly used is the heterodyne bat detector. These detectors take the echolocation that the bats use to locate their prey and convert it into a sound that can be heard by humans. The differences in the calls, their frequency, repetition rate and tonal qualities can all be used to help distinguish different species.

During the survey last night I had Common Pipistrelle bats visiting from 20.27, 18 minutes after sunset. They continued to feed until around the building until 21.30 when they became more intermittent visitors to the site. The best part of the survey however was the arrival of a Myotid species of bats. These bats produce sounds on the heterodyne bat detector that are sharper ticks compared to the wetter slaps of the Pipistrelles. They continued feeding around the buildings until around 21.50 when they became intermittent. Their echolocation calls on the Pettersen D200 bat detector was a series of fast tiks, with a tonal quality similar to walking over straw. They are probably Natterer’s bats but I’ll have to return to site to gather more evidence before being sure.

Wednesday 27 August 2008

How many species of bats are there in South East Staffordshire?

There are 9 species of bats that have been recorded in South East Staffordshire. These are;
Brown Long Eared bat. Plecotus auritus.
Common Pipistrelle. Pipistrellus pipistrellus.
Soprano Pipistrelle. Pipistrellus pygmaeus.
Noctule. Nyctalus noctula.
Leisler’s bat. Nyctalus leisleri
Whiskered bat.Myotis mystacinus.
Brandt’s bat. Myotis brandtii.
Daubenton’s bat.Myotis daubentonii.
Natterer’s bat.Myotis nattereri.

All bats are protected by law.

Some of these bats can be seen and heard when attending bat walks arranged in conjunction with the South East Staffordshire bat group. These walks start at sunset and carry on for an hour or more. The bat group members will take groups of people on the walk and help them to look for bats and listen to them using bat detectors.

Thursday 21 August 2008

What is the optimum time to conduct a bat survey?

Bat surveys should be conducted between May and September. This is when bats are most likely to be present and not hibernating.

Tuesday 19 August 2008

How many bats are there in South East Staffordshire?

There are 17 species in the UK but in this part of the country there are just 9 which are:
  • Common pipistrelle
  • Soprano pipistrelle
  • Brown long-eared bat
  • Whiskered bat
  • Brandt's bat
  • Natterer's bat
  • Daubenton's bat
  • Noctule
  • Leisler's bat