Keep up to date

Keep up to date with the latest posts David's Bat Blog on Facebook

Sunday, 29 June 2008

Swarming Pipistrelle Video

A few weeks ago I included a brief snippet of video, showing a colony of Soprano Pipistrelles (Pipistrellus pygmaeus) swarming at dawn, before entering their roost. I have now had opportunity to film a longer video with a larger colony.

The video was recorded between about 04.10 and 05.00 on a morning when dawn was around 04.30. A colony count the evening before showed that 383 bats left the roost. I hand-netted two of them and both were lactating females, indicating that this is a maternity colony. When I filmed them it was too early in the maternity season for the young to be flying, but in just a few weeks there will probably be double this number of bats, as each young bat starts to follow it's mother out to feed at night.

The video shows up to fifty bats at a time swarming and there are close-ups of one of the roost entrances, showing how the bats "touch and go" at the entrance, without actually entering. At times, so many bats were attempting to do so that there was an aerial queue and the clattering on the wooden barge-board as they touched and pushed off again was audible some distance away.


My web-site

Thursday, 26 June 2008

Welsh Bats and Scottish Bat-workers

Last weekend I made the long trek to Aberystwyth - a 7 hour drive each way - for the B.C.T. Welsh Bat Conference. Organised by Tom McOwat and hosted by Aberystwyth University, this was an excellent conference at a reasonable charge (even for us consultants, who usually pay extra). A pleasant surprise was the discovery that no less than nine of us were travelling down from Scotland, so with a bit of hectic organisation everyone squeezed into two cars and we did our small bit to save the planet and avoid having to remortgage the house to buy a tank of petrol.

There were a number of good talks. It would be remiss of me not to mention the two Scots: John Haddow describing tips for identifying bats in the hand and Kirsty Park on bats in man-made habitats.
Another highlight for me was Helen Miller describing BCT's new survey programme for the rare Bechstein's bat. This rare woodland bat is extremely hard to survey for: they fly fast and cover large distances, so the survey method employs an actic technique: using ultrasonic lures to attract Bechsteins into harp traps by broadcasting their social calls. Very clever, and with a strict methodology that minimises disruption to the bats.

Another fascinating talk was by Chris Corben, the innovative Australian who designed the Anabat system, which is revolutionising professional bat-work. The Anabat SD1 is a frequency division detector which saves data direct to a CF memory card. It allows effective long-term monitoring of bats and is increasingly finding a place in transect work too. With the associated Analook software, which is designed to work with frequency division data (unlike Batsound etc, which use audio files) it is astonishingly easy to analyse large numbers of bat passes swiftly and efficiently.

A very clever idea incorporated into the conference was the usual evening bat-walk. Except it wasn't the usual one. Instead, all the delegates were divided into teams and spread out over twelve woodland sites around Ceredigion. The result: a far greater survey effort in one night than most bat groups could manage in a year. And to validate the results, the Sunday morning session comprised analysis workshops for the various software programmes.

Naturally, the Scottish bat hooligan squad had to push things to the limit. Not satisified with six bat species in our patch of woodland (including a possible Nathusius' Pipistrelle - a very rare species), we wanted more. We set out to look for Lesser Horseshoes, which we were told had been recorded at a road widening scheme a few miles from Aberystwyth. Imagine the scene: a car bursting with wild bat enthusiasts and literally bristling with bat detectors, careering down a Welsh country road in the middle of the night. We had three Bat-box Duets poking out of the sun-roof (set to 20, 50 and 120 kHz), an Anabat SD1 poking out of the side window and one intrepid bat-worker (who shall remain nameless) hunched in the passenger seat, monitoring the frequency division output of one of the Duets, just in case a bat escaped all the other detectors.

So, did we get any Horseshoes? Did we heck. But at least we have an excuse to go back to Wales...if they'll have us!

My website:

More on the Bechstein's Project:

Chris Corben and Anabat:

Tuesday, 24 June 2008

A Rant About Planning

Early in 2007 the Scottish Government (or was it still the Scottish Executive then?) wrote to all local authorities in Scotland, clearly setting out their responsibilities in relation to European Protected Species (which include all UK bat species) and the planning process. What they said includes some very simple guidance: " is clearly essential that planning permission is not granted without the planning authority having satisfied itself that the proposed development either will not impact adversely on any European protected species on the site or that, in its opinion, all three tests necessary for the eventual grant of a Regulation 44 licence are likely to be satisfied." Surely that isn't hard to understand?

Why then, are some local authorities still granting planning permission for developments without giving the slightest consideration to protected species? Edinburgh are the worst offenders I know of, but I'm sure there are others. I have recently seen a development involving the direct destruction of a known roost. I was called in by the owner to give advice on how to proceed and was appalled to discover that planning permission had already been granted.

On the other hand, some local authorities are diligent: the planners at Scottish Borders Council not only make it clear to applicants what species need to be surveyed for, they provide succinct guidance, written by the county ecologist and clearly focused on the individual development.

This process is the safety net through which pointless destruction of bat roosts can be prevented: ensuring developers and others face their responsibilities towards protected species and helping them understand what they need to do and when. It's basic and essential conservation law.

My other frustration is the local authorities who approach their Habitats Directive responsibilities with a "one size fits all" approach. One west of Scotland local authority responds to planning applications by setting out what programme of surveys must be carried out, without knowledge of the characteristics of the site or it's bat potential. Yet the BCT Bat Survey Guidelines are clear: "It is worth noting that the type of survey to be undertaken and amount of effort expended can often only be fully determined after visiting the site at least once." I recently completed a pointless set of sunset surveys at a modern city centre building with very low bat potential, no nearby or connected habitat and no records of bat activity in the area. The local authority's ecologist insisted on his standard litany of "two to three emergence surveys", with no mention of an initial inspection survey. After I carried one out it was abundantly clear that no further survey was necessary, but was obliged to do so anyway. As a result, the developers have been delayed, have paid over the odds and are disillusioned with the whole process. In other words, conservation has been discredited by thoughtless actions.

For all I know, their next development could be a steading conversion surrounded by prime habitat: a building with high bat potential. After their bad experience at this site, they could be tempted to turn a blind eye to protected species. If the local authority is one of those which does the same, the result could easily be the destruction of an ecologically sensitive roost.

Rant over (climbs down from soapbox).

Tuesday, 10 June 2008

Pipistrelle Roosts: from Intermediate to Maternity

The roosting cycle of the commoner UK bat species is reasonably well understood: hibernaculum in winter, then move to an intermediate roost in spring. In the breeding season, the females move into maternity roosts and in most species the males use other sites. Once the young are flying in late summer, intermediate roosts become important again, with mating roosts used in some species, then it's back to hibernacula. More often than not, we only see little snippets of this and have to work hard to interpret what we see. I've been lucky enough to see a slightly bigger piece of the picture with two Soprano Pipistrelle (Pipistrellus pygmaeus) roosts I've been working with recently.

The first is the site at which I videoed swarming bats in May ("Dawn Swarming", 15 May). On that occasion I saw around 70 bats swarming, 30 of which entered the roost, the remainder flying off to the north-east. We know of another roost about 500m away in that direction, so clearly there was likey to be a link. Last week I returned at sunset to do a colony count and volunteers from Lothians Bat Group went to the other roost site to the same thing simultaneously. 48 bats had been counted at the other site a week previously, so I was intrigued to see which roost would be used for breeding.

Unexpectedly, only three bats emerged from "my" roost. I hand-netted one of them, which turned out to be a very small non-breeding female. She was in poor condition and was carrying an enormous (by Pipistrelle standards) Cimex bat-bug (a close relative of the human bed bug) on one wing and huge numbers of Macronyssidae (a family of tiny mites).

Incidentally, it's quite unusual to see a bat-bug attached to a bat outside of the roost. They are not really equipped to grip on to a rapidly moving wing for long and normally feed from bats within the roost, dropping off before the bats emerge, so it looks like this one got caught out! It's probably Cimex pipistrelli, but there are records of another, rarer Cimex species on bats and I'll reserve judgment until I have it under the microscope.

Here you can clearly see the Bat-bug (Cimex sp.) on the bat's wing

And the other site? Only thirty bats emerged, suggesting that the maternity roost is probably somewhere else entirely. What we now need is someone mad enough to prowl the streets of Edinburgh at dawn for a few days, looking for a swarm of bats, to tell us where the maternity roost is! It's not that we really need to know, but it would be nice to find the missing jigsaw piece.

The other site is the one I mentioned in February ("Two Roosts for the Price of One", 6 February), with droppings of two species in the attics. As yet the Brown Long-eareds (if my dropping analysis is correct) haven't put in an appearance. At dawn one morning in May, I watched 7-10 Soprano Pipistrelles swarming around the gable end of the "wrong roof", i.e. the attic which did not have Pipistrelle droppings in it in February. Did I have it all wrong? Was the maternity roost actually here?

(Above) The roost entrance identified in May - the bats swarmed in front of this gable end and entered via the gap visible below one of the roof tiles

(Below) Droppings stuck to the timber facing below it, 3 weeks later

When I returned with a team of helpers at sunset last week, there were many droppings stuck to the wall around the access hole the bats had been using on the previous visit, indicating it had seen some use. However, at sunset no bats emerged from there. Instead, 118 bats emerged from two holes in the gable end of the main attic, right where I originally found piles of droppings within the attic. So, not only were we able to confirm the location of the maternity roost, the May visit enabled the identification of an intermediate roost, which wasn't apparent from signs within the attic.

Bats are always enigmatic and rarely give up their secrets easily. It's nice when, once in a while, we can see tiny bit more of their lives than the usual tiny snap-shots...

My website: