February 9, 2022 • 26 mins
S3E31 This week Steve is on the Tortworth Estate in south Gloucestershire with Jim Mullholland. They're joined by a voluntary team of arborists who are assisting Jim with his 5 year project to create natural tree features for Bechstein's and barbastelle bats. By using chainsaws to create different crevices and cavities within living trees, the team hope that they will be taken up by colonies of the two bat species which are present in the woodland Steve is visiting today in this episode. The episode starts on a sunny spring day in an ancient woodland with chiffchaff singing in the canopy overhead. As the episode moves down to where the team are working for the day there's more background noise than you're used to on BatChat because the woodland is right next to the M5 motorway.
- Jim Mullholland is on twitter and Instagram
- Jim has a YouTube channel with a number of videos of bats inside tree roosts.
- The Tortworth Estate opens to the public on certain days of the year. Find out more here.
- Listen to our other episodes on veteranisation with Jim and Vicky Bengtsson
- A guide to veteranisation techniques is at this link.
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Producer: Steve Roe @SteveRoeBatMan
Cover Art: Rachel Hudson http://rachelhudsonillustration.com/
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Steve Roe (00:09):
This week we have Bat Conservation in action for you
in South Gloucestershire. Thisis BatChat from the Bat
Conservation Trust.
(00:29):
Hello, and welcome to BatChat.
This is the podcast where webring you the stories from the
world of bat conservation. I'mSteve Roe a BCT Trustee. And if
you're a regular listener, it'sgood to have you back with us.
And if this is your first timelistening to BatChat, welcome
along. Episodes are beingreleased every second Wednesday
from now through to the spring.
And you can join theconversation online using the
(00:50):
hashtag BatChat that's all oneword. As we meet each of our
guests, you'll hear from peopleworking to make a difference in
the world of bat conservation.
As well as keeping up with thelatest news and hearing from
people in the world of bats. Wehope that you'll be inspired to
get involved because bats needour help. Now if like me, you're
looking forward to the sunnydays of spring, you'll like
these next few minutes. Back onepisode 11 we had Jim Mulholland
(01:11):
talking to me about hisveteranisation of trees
projects. And last March Ijoined him out in the field on
an estate in Gloucestershire, insome woodland, where a team of
arborists are volunteering theirtime to help him with his
projects. So we joined Jim atthe start of the day in an
ancient woodland, where heexplains what the plan for the
day is, and tells us about theproject he's got running on the
estate. Later on in thisepisode, there's slightly more
(01:33):
background noise than you'd usedto hear on BatChat because of
the site's location right nextto the M5 motorway. So it's a
nice spring day, at the end ofMarch, chiffchaff singing, and
Jim Mulholland is back on andwe're in South Gloucestershire
on an estate called theTortworth Estate. So Jim, nice
(01:54):
to have you on again, what isthe Estate and who owns it?
Jim Mullholland (02:01):
The Torworth Estate is perhaps one of the
best states in the country forbats, as Steve raises his
eyebrows at me
Steve Roe (02:08):
Big claim, big claim
Jim Mullholland (02:09):
It is a big claim. But I can substantiate
that. We have 15 of the UKspecies here. The only ones
we're missing a grey long-earedand Alcathoe, and I'm hopeful
for Alcathoe like everyone elseis I guess in the country.
Steve Roe (02:21):
I mean, that's pretty good, isn't it?
Jim Mullholland (02:22):
It's pretty good. It's not bad at all. And
considering it's five minutesfrom where I live, all the
better. It's a privately ownedestate. I think it comprises
somewhere in the region of 2500acres. And it's a mix of
wonderful habitat. So we arecurrently sat in Daniels wood.
And this is an area of ancientsemi natural woodland. And it
has other habitats such asorganic pasture has two
(02:45):
freshwater lakes. It has lots ofold buildings. And my original
involvement here was to do withlesser horseshoe bats, which
were hanging up in theoutbuilding of Robert and
Sally's house. And they keptseeing all this poo on the mower
and thought it was a huge colonyof mice that had moved in and
(03:05):
then suddenly decided to look upand saw these bats. And it kind
of started from there as I wasinvolved with some work with
lesser horseshoes, and itsnowballed from there. And so
we've been involved withNathusius', the National
Nathusius' project led by DanielHargreaves down at the lake. And
we recorded them down therealthough we didn't catch any.
We've had sightings of Leisler'sI had a wonderful evening where
(03:26):
I was looking at about thinking,it looks like a noctule, it
sounds a bit like a noctule butit's a little bit too high. And
then all of a sudden, thenoctule appeared next to it.
And so had the confirmation andthen subsequently we find a
young Leisler's in about a boxas well. I've been working here
since the it's 2013. And my workfor the last five years or so
(03:48):
has been very much focused onbaps and trees here. And so my
evidence base for the two talksat the National Bat Conference
come from largely from data fromthese sites. And we're on to the
new chapter today.
Steve Roe (04:01):
And the rumble that we can just hit the background
is the M5 motorway so forlisteners who travel south on
the five and pass the MichaelWood services, the block of
trees over the hill on the leftis basically where we are. So
what are we doing here inDaniels wood. There's about
seven arborists working justdown at the bottom of the field
from us. And we'll come on tothat later. But what are we
(04:24):
doing up here in Daniels wood.
Unknown (04:25):
At the moment I'm trying to get my tablet to work,
which isn't playing ball. But weare doing some work as part of
our five year project funded bypeople's trust for endangered
species. The arboriculturalassociation is supported by
Stihl and the title of that isimproving the future for to
Woodland bat species. We havetwo main strands of the project.
(04:46):
The first one is focusing on theefficacy and efficiency of tree
surveys for bats. And it's atopic that I've spoken a lot
about and raise the issue thatthe service that we undertake
are really quite limited, Istarted some work trialling the
use of trail cameras to see ifwe could use them use technology
(05:07):
and replace surveyor efforts. Sothe first strand of the project
is really just refining that. Sowe have a number of Bechstein's
and barbastelle tree roots here.
And we will be deploying thosetrail cameras to see if we can
improve and refine that approachand and hopefully see that begin
to roll out and improve ourservice for bats in trees. The
second strand is then moving thenext step, which is the really
(05:30):
exciting step, which is can wecreate that roost in trees by
wounding them in deliberateways. And this is something that
various people have tried for anumber of years, I believe. And
I think the the main limitationwith previous work is that it's
just not been monitored. Andthat's because it's very, very
difficult to establish whetherbats are using a tree. So we
(05:50):
have the two elements of theproject really coming together
that we will create thesefeatures. And the design of
those is very much guided by thedata from the battery habitat
key. And then once we havecreated them, we'll be in a
position where we can use thetrail cameras to establish
whether they're used, andhopefully, they're used by the
species that we intended to beused by. So one of the strands
of the project is to look at thetemperature and humidity
(06:14):
regimes, both in naturalfeatures, the features that we
create, and we are in Danielswood at the moment, because we
are going to put some dataloggers in bat boxes to see how
they compare.
Steve Roe (06:25):
I think last time you came on, I accused you of
trashing trees. And then sincethen, we've had Vikki Bengtsson
on the podcast and she talksabout the project she's been
doing both here in the UK andacross Europe. And the results
from that a pretty spectacularreally so it's nice to see
somebody else's taken on here inthe UK, the data loggers you've
got so they're their dataloggers, the are familiar to
(06:46):
people who do that work. Andtypically they go in caves and
roost sites. How are you fixingthem into that boxes today?
Unknown (06:54):
Good question. Not really sure. The flat Schweglers
have a section of wood at theback. So we will screw a small
screw in that and then hang themfrom a piece of wire. I think
for the rain Schweglers I'llhave to settle for just resting
them at the bottom of the boxand hope that that's gives us
some data. I admit that that'snot where the bats will
(07:14):
necessarily be roosting but itwill give us some comparison, at
least for an empty bat box andan empty cavity. Yeah, great
stuff. Vikki was my boss at theancient tree forum. Yeah, so
that's my first box and theancient tree forum and she's
inspirational. Think we so thisproject actually came from
(07:34):
working with Vikki on a Europeanproject called vet search where
we were developing acertification scheme for veteran
tree management. And I've kindof had this realisation that we
do fantastic work in ecology, wedo fantastic work with bats, and
typically we scrimp and save andtry to find the money to do the
work. And I was delivering atraining course with Vikki. And
(07:54):
she basically flipped that onhis head and said that through
the years she worked inconservation, they will find
money here, they will scrimp andsave and try and get what they,
they need to do an okay job. Andactually, we do fantastic work,
just need to sell it better. Sowe need to say, this is valuable
for this reason. And it's worththis much. And therefore I want
(08:15):
this money, we should be goingafter the big fingers really.
And it's about asking for whatwe need rather than what we
think we will get away with. Andso that inspired me, Vicki and I
then were delivering anothertraining course in Finland, we
were sat in a bar discussingvarious projects and her work.
And that's where the embryo ofthis project was born. And so I
(08:37):
came back from Finland andwithin three weeks, the people's
trust for endangered species hadtheir current round of grant
closing was finishing, that didnot make any sense. Within three
weeks, the people's trust forendangered species had a
deadline for one of the grantapplications. So I submitted and
here we are. Now I need to focuson this because otherwise I
(09:02):
won't run out of battery why isthis tablet not working
Steve Roe (09:11):
So Jim, we finished putting out the data loggers in
Daniel's would come down to thebottom of the fields. And we can
tell we're a lot closer to themotorway. And we can hear bits
and pieces of chainsaw noise inthe background. What are the
guys and the trees down heredoing?
Unknown (09:24):
So they are working on the trees that will be used for
creating the bat roosts. So thefirst step is to remove the top
of the tree. And that's becausewe are cutting features into
tree and we're worried aboutpotential failure through
torsional loading. So twistingmotion of the tree. So that's
step one. So we have four orfive people down there at the
moment, just taking the top setof trees. Then the next step we
(09:47):
will be looking at actuallycutting the features into the
trees themselves. So we have twospecies we're catering for.
We're looking creating roots forBecstein's and barbastelle and
for each species, we are tryingwhat we're calling instant
roosts and future roosts. So theinstant roosts, as the name
would suggest, suitable oncethey are cut effectively, it's a
(10:10):
bat box in a living tree. Andthis is similar to a lot of
other work that's been going onpreviously, if cutting slits,
etc, they are perhaps slightlymore tailored to the individual
species roosting requirements,that the idea is that yeah,
we'll take a section of tree outkind of a wedge from the front,
we take the back off of it, wecut an entrance into it, and
(10:30):
then we reinsert that lid,effectively, the future roosts
where we are cutting wounds intothe tree with the idea of
anticipating how the tree willrespond and how it will grow
after the wounding. So work fromVikki Bengston, who you
mentioned earlier, she has anest box designed to the
(10:51):
incident routes is very muchlike the nest box designed but
it's it's tailored for bats. Herwork has shown that after maybe
five or so years, the lead getsbasically spat back out of the
tree, as if the tree isrejecting it. Because it's no
longer living, it's no longerpart of that tree. So in
conservation, we're looking athaving various tools, and one of
them might be an instantprovision. But also we're
looking at longer termprovisions as well. So the
(11:13):
future roosts are doing justthat. So we cut features into
the tree, they're open to beginwith. As the trees continue to
grow, they will callus over. Andthey will close over entirely.
So effectively, what we shouldend up with something is very
similar to a natural featuresthat's covered in living
functional wood. So we havewater moving through that word,
it means that the temperaturehumidity regime should be as
(11:35):
close as possible to livingtrees as natural features as
possible.
Steve Roe (11:39):
And why are these better than bat boxes?
Jim Mullholland (11:42):
We don't know at the moment is the question.
So we are experimenting, I guesswe are looking at can we
increase the size of ourtoolbox. And this is something
that Vicki talks about as wellthat they will not be suitable
in all situations. We haveselected trees here with the
foresters that are of loweconomic value and low
ecological value. So they wouldhave heard of or otherwise been
removed. And it's all aboutexpanding the size of the
(12:04):
toolbox. We know that that boxeshave their place. But we also
know from studies that thetemperature and humidity regimes
are not as good or not the same,at least as natural cavities.
And the concern there is thatthe individuals that use them,
especially if they're breeding,perhaps will be less healthy if
they're less healthy, or they'regiving birth to young that are
(12:24):
less healthy, and well that havea knock on effect to the
populations year on year onyear. So it's increasing the
size of the toolbox.
Steve Roe (12:34):
Right, we're going to head down the hill and on top
some of the top guys were makinga lot of noise
Jim Mullholland (12:39):
they are it's getting smoky here as well
Steve Roe (12:43):
sort of comes down the bottom field and we're now
in fairly steep woodland, and wecan see the traffic on the M5
motorway. There's a guys makinga lot of noise up a tree. Taking
the top of the tree out like itwas
Unknown (12:59):
probably 15/20 metres up the tree. It's raining
sawdust.
Steve Roe (13:04):
Once you taken the top out of this tree where
abouts on the tree is he makingthis cut? making
Unknown (13:07):
the call, we will be creating them between five and
10 metres on the main stem. Sowe're focusing all of the
features on main stem we chosefive to 10 metres because that's
what the data from the bat treehabitat key says that we should
do. Basically it talks about thehighest proportion of maaternity
roosts recorded the trees are inthat region. That could be down
(13:28):
to bias in data. But obviouslywe know that there's probably a
preference to roost at a certainheight so below five metres is
probably unsuitable and higherthan that potentially gets less
suitable as well because thebats experience more movements
in the wind, etc.
Steve Roe (13:43):
It's not a very dense woodlands. It's quite windy
about the winds. Quite quickly.
Do you know that there are barbsand Bechstein's in this bit of
woodlands or is this an areayou've not surveyed yet.
Unknown (13:52):
So we're in Daniels wood still we're at the other
end of Daniels word and the topend of Daniels words is in a U
shape so overall the woodlandstend to be in a Y shape. If you
mentioned sticking the the southend on bottom. We are basically
the furthest north you can goand the furthest west you can go
right next to the M5. TheBechstein's pretty much all
(14:13):
roosted within Daniel's wood,albeit slightly further south
than where we are. There is onetree roost that's, maybe 300 400
metres from here Bechstein'sbats. The barbastelles however,
they do use the woodland and Icatch them on the rides in The
Woodlands on the other sidewhere we just were looking at
the bat boxes. But to myknowledge, they don't roost in
this woodland so they roostfurther south from here they
(14:35):
roost further north from here,but I haven't yet recorded any
barbastelle roosting in thiswoodland. The trees we selected
we have three sites on theestates for creating these
features. We have Daniel's woodwhere we are now. Next week, we
will be working in a regioncalled Hawkers Grove, which is
further south and then we willbe finishing off by one of the
legs. And so we kind of spannorth to south maybe about two
(15:00):
kilometres between the threeareas. And that encompasses more
of the areas where thebarbastelle roosts are.
Steve Roe (15:07):
And what are the what are the tree species? When
you're targeting? Are youtargeting particular species for
the two different species ofbats? Are you just trying to
connect with them,
Unknown (15:15):
I'm less worried about individual tree species,
especially for the instantroosts. Because we're not
waiting on any decay processes.
We're not waiting on the treesto respond. We're essentially
creating bat boxes and livingtrees, it would have been nice
to use just one tree species forconsistency. However, I had to
go with what the foresterprovided me with essentially. So
(15:36):
we have a mixture. And it's amixture of oak mixture of ash,
sweet chestnut, and somesycamore as well, it depends.
The makeup of individual treespecies varies through the three
different woodlands that we'reworking within Ash is going to
be an interesting tree species.
(15:56):
The forest, as you can imagine,was very happy to give me all
the ash trees that I wanted. ButI limited in the number that
we're using just throughconcerns over the longevity and
future stability. I'm stillhappy to create them in them, I
think it will be a usefulexperiment. There's lots of talk
about at the moment about whatwe are going to do with ash
(16:18):
trees. First of all, the hope isthat we won't lose all the of
the ash trees. Second of all,there will be some that will
contract ash dieback but surviveso they kind of get it and come
out the other end. Okay. We knowthat trees that are in the more
natural setting, more diverseecosystems are more likely to be
resilience to as diverse and sowe're in at least in Daniels
(16:41):
wood, we're in an area ofancient semi natural woodland,
some fantastic ground floraaround us at the moment. So the
soil ecosystem here should befairly healthy. This section
we're in now is a nonintervention area, with the
exception of what we're doingclearly. So yeah, I'm cautiously
optimistic about our ash diebackhere, however, it is inevitably
(17:01):
going to have an impact.
Steve Roe (17:03):
Yeah, I mean, you say the grand falls nice. I mean,
you can't actually see much soilat all you've got bluebells
starting to poke through thecarpet of dogs mercury, there's
some wild garlic starting. Sothe smell of thats drifting down
the hill. Yes, nice woodanemonie as well.
Unknown (17:20):
Okay looks liek the final guy has come down. It's
teatime!
Steve Roe (17:25):
So after a tea break from taking the weight out of
the top of the canopy, we joinMark back at the tree where he's
now going to create the actualfeature for Bechstein's on the
trunk. So the feature that'sMark here is that to make say,
an instant feature, so it's likecreating a what essentially a
bat box would do within anatural tree feature. So they're
cutting a long rectangular blockof wood out of the main stem of
(17:50):
the tree, the tree trunk, andthen they're cutting in from
behind to release the back ofit. And that's been released and
lowered down to the ground and achunk of that shaved off so that
when it's placed back in themainstem and put in place with
nails or screws, there's anatural cavity then then created
and that's what Mark is about tocreate. So Mark was just telling
(18:14):
me that he's been an arboristfor about the last 20 years. Is
this the first time you've donethis sort of work on this? For
this reason?
Mark (18:21):
Yes, bat roost creation like this. I've done coronet
cups. I've done all boring holesfor the birds and stuff like
this. But yeah, specificallythis precise A bat roost habitat
creation and that sort of stuff.
I've done various surveying forbats looking for them in holes
in trees, but actually creatingscratches. First time I've been
Steve Roe (18:39):
Watching Sean there do it on the ground look fairly
straightforward. How complicatedis it being stuck in a harness
on a rope?
Mark (18:45):
it's a little bit trickier because you're using the tip of
the bar and you've got tobalance it and it's not. It's
not the sort of cutting you makeon a daily basis. It's not the
sort of thing you do when you'repruning branches are cutting
chunks off. So it's slightlydifferent. On the day to day as
an arborist have a it's the sametechniques, it's using the sword
same way but it's just slightlydifferent to how you do it.
Steve Roe (19:06):
I'll let you get on with it. You don't see Claire
Balding doing this on herpodcast I'll tell you that much!
So this is a BatChat first I'm10 metres off the ground in a
harness and I'm next to Markwho's got a chainsaw in his
hands so Mark just describe whatyou're about to do.
Unknown (19:25):
I'm about to cut a big slot, either side of this oak
tree 1.3 metres long down thetree about 10 centimetres wide.
We're going to remove that slotlower it from the ground, cut
the back off it to createhabitat for neck stones habitat.
(19:45):
So yes, I'm going to make twoparallel longitudinal cuts down
the stem of the tree bout 15centimetres deep to measure my
chainsaw to work out with 15centimetres a lot easier.
Steve Roe (20:29):
So you can hear Mark is now making the final cut
around the side of the tree justto the left of where he's made
the front cuts and that willrelease a metre long piece of
wood along the length of thetrunk which will be lowered down
to the ground we worked on thetrusses nice and clean himself a
(20:51):
nice little comfy position nowset on the branch halfway up the
tree. And as I'm still to watchhim now there's a whole range of
orange florescent jacketsthrough the woodlands some of
them halfway up trees some ofthem on the ground as the team
works on four trees around us.
(21:17):
The thumping noise is Mark hidin the piece that he's cut with
the back of his hook, which he'sgoing to use
Mark's having to go around theright hand side of the piece
because the branch that he wassat on earlier, is now in the
way of where he needs to makethe cut. And the cut that's been
(21:40):
made is facing south and it's anoak tree. There's probably about
20 metres high and the cut'sbeing made it around eight to 10
metres up and there's no lowerlens on there. So true. Please
get it in the bottom now it'slooking quite carefully and he's
got to the now. Now it's timefor the final test with the axe
(22:01):
and there's one resistant bit inthe middle which is just not
going to be released easily
Unknown (22:06):
At the top have you gone up above the opening?
Steve Roe (22:24):
So Jim just described the feature on the tree behind
the one that Mark's working onthis is for barbastelles.
Unknown (22:31):
So Will's creating one of the future roofs, it's
essentially just a long slit inthe face of the tree. And the
idea there is that we create asplit or crack type feature we
created a slightly wider openingand it's tree continues to grow
and callus around the wounditself. It covers over the
(22:53):
majority of it and just leavesthe small opening
Steve Roe (22:58):
Mark now it's just lowering this metre long block
of wood that is cut out fromfrom the tree he's been working
on. The piece is now on theground with Jim and Mark is just
coming down.
Jim Mullholland (23:11):
I have aweird hobby!
Steve Roe (23:20):
So as the features are being brought down, they're
being piled in the middle of thewood for everyone to work on. So
the team have just been makingcuts on the two metre long
sections one for barbastelle andone for Bechstein's and Mark is
(23:42):
heading up the tree now to thecavities currently got there to
place the data logger and thetop which is where hopefully the
bats will be roosting and thenthe metre long session will be
censored so it can be screwed inplace
(24:04):
so Jim is now attaching themetre long session to Mark's
rope which is now getting hauledup. So in the front of Mark's,
block of wood which is goingback in place there are two
vertical slips which have beencut to 40 centimetres from the
(24:25):
top and bottom and on theadjacent tree. The block has had
a artificial woodpecker holedrilled in using the battery
powered electric drill.
Woodpecker holes been designedfor Bechstein's and the two
slits on mastery here designedfor barbastelle
Jim Mullholland (24:46):
It's one tree per day per person.
Steve Roe (24:48):
So this is first time the team have done this and we
met at 10 o'clock this morningand it's now getting on for four
o'clock but Jim hopes that aspeople return to the site and
repeat the same process forother trees that the process
will become faster. So Mark isnow attaching the datalogger to
the top of the feature.
And that's it, the piece is backin place there's four screws
(25:20):
then holding it in place.
and thanks to Jim for having mealong for the day. And thank you
to you for listening to thisepisode. I hope you've enjoyed
it. If you take a look at theshow notes, you'll find links to
Jim's social media and our otherepisodes on this subject. Now
this series we are running backchats first ever competition.
(25:42):
children's authors Emma Reynoldsand Angela Mills have kindly
donated prizes. Angela hasdonated a copy of Bobby the
brown long-eared bat signed byboth Angela and Chris Packham,
and Emma has donated a copy ofher newly released book Amara
and the bats. To enter thecompetition to win one of these
brilliant books. All you have todo is write as a review about
this podcast BatChat. And thetwo winners will be picked at
(26:03):
random at the end of the series.
So there's only a few weeks leftto do this. Not all podcast apps
allow you to leave reviews soyou can find instructions in the
show notes of this episode. Andplease note that we're only able
to post prizes to addresses inthe United Kingdom. The series
continues in two weeks time withthe author of Bobby Brown on
good bat, Angela mills. So untilthen, I'll leave you with a clip
of that next episode. I'll seeyou then.
Angela Mills (26:27):
You know, Chris Packham did the foreword, which
is always lovely. And Kate doessome lovely illustrations. So as
my first attempt, I think it'sbeen a pretty good attempt when
I go into schools and read thebook. You know, the kids are so
enthusiastic, and I even had onelittle boy say to me once, this
is the best day of my life, andI thought, Wow, that's amazing.
This week we have Bat Conservation in action for you
in South Gloucestershire. Thisis BatChat from the Bat
Conservation Trust.
(00:29):
Hello, and welcome to BatChat.
This is the podcast where webring you the stories from the
world of bat conservation. I'mSteve Roe a BCT Trustee. And if
you're a regular listener, it'sgood to have you back with us.
And if this is your first timelistening to BatChat, welcome
along. Episodes are beingreleased every second Wednesday
from now through to the spring.
And you can join theconversation online using the
(00:50):
hashtag BatChat that's all oneword. As we meet each of our
guests, you'll hear from peopleworking to make a difference in
the world of bat conservation.
As well as keeping up with thelatest news and hearing from
people in the world of bats. Wehope that you'll be inspired to
get involved because bats needour help. Now if like me, you're
looking forward to the sunnydays of spring, you'll like
these next few minutes. Back onepisode 11 we had Jim Mulholland
(01:11):
talking to me about hisveteranisation of trees
projects. And last March Ijoined him out in the field on
an estate in Gloucestershire, insome woodland, where a team of
arborists are volunteering theirtime to help him with his
projects. So we joined Jim atthe start of the day in an
ancient woodland, where heexplains what the plan for the
day is, and tells us about theproject he's got running on the
estate. Later on in thisepisode, there's slightly more
(01:33):
background noise than you'd usedto hear on BatChat because of
the site's location right nextto the M5 motorway. So it's a
nice spring day, at the end ofMarch, chiffchaff singing, and
Jim Mulholland is back on andwe're in South Gloucestershire
on an estate called theTortworth Estate. So Jim, nice
(01:54):
to have you on again, what isthe Estate and who owns it?
Jim Mullholland (02:01):
The Torworth Estate is perhaps one of the
best states in the country forbats, as Steve raises his
eyebrows at me
Steve Roe (02:08):
Big claim, big claim
Jim Mullholland (02:09):
It is a big claim. But I can substantiate
that. We have 15 of the UKspecies here. The only ones
we're missing a grey long-earedand Alcathoe, and I'm hopeful
for Alcathoe like everyone elseis I guess in the country.
Steve Roe (02:21):
I mean, that's pretty good, isn't it?
Jim Mullholland (02:22):
It's pretty good. It's not bad at all. And
considering it's five minutesfrom where I live, all the
better. It's a privately ownedestate. I think it comprises
somewhere in the region of 2500acres. And it's a mix of
wonderful habitat. So we arecurrently sat in Daniels wood.
And this is an area of ancientsemi natural woodland. And it
has other habitats such asorganic pasture has two
(02:45):
freshwater lakes. It has lots ofold buildings. And my original
involvement here was to do withlesser horseshoe bats, which
were hanging up in theoutbuilding of Robert and
Sally's house. And they keptseeing all this poo on the mower
and thought it was a huge colonyof mice that had moved in and
(03:05):
then suddenly decided to look upand saw these bats. And it kind
of started from there as I wasinvolved with some work with
lesser horseshoes, and itsnowballed from there. And so
we've been involved withNathusius', the National
Nathusius' project led by DanielHargreaves down at the lake. And
we recorded them down therealthough we didn't catch any.
We've had sightings of Leisler'sI had a wonderful evening where
(03:26):
I was looking at about thinking,it looks like a noctule, it
sounds a bit like a noctule butit's a little bit too high. And
then all of a sudden, thenoctule appeared next to it.
And so had the confirmation andthen subsequently we find a
young Leisler's in about a boxas well. I've been working here
since the it's 2013. And my workfor the last five years or so
(03:48):
has been very much focused onbaps and trees here. And so my
evidence base for the two talksat the National Bat Conference
come from largely from data fromthese sites. And we're on to the
new chapter today.
Steve Roe (04:01):
And the rumble that we can just hit the background
is the M5 motorway so forlisteners who travel south on
the five and pass the MichaelWood services, the block of
trees over the hill on the leftis basically where we are. So
what are we doing here inDaniels wood. There's about
seven arborists working justdown at the bottom of the field
from us. And we'll come on tothat later. But what are we
(04:24):
doing up here in Daniels wood.
Unknown (04:25):
At the moment I'm trying to get my tablet to work,
which isn't playing ball. But weare doing some work as part of
our five year project funded bypeople's trust for endangered
species. The arboriculturalassociation is supported by
Stihl and the title of that isimproving the future for to
Woodland bat species. We havetwo main strands of the project.
(04:46):
The first one is focusing on theefficacy and efficiency of tree
surveys for bats. And it's atopic that I've spoken a lot
about and raise the issue thatthe service that we undertake
are really quite limited, Istarted some work trialling the
use of trail cameras to see ifwe could use them use technology
(05:07):
and replace surveyor efforts. Sothe first strand of the project
is really just refining that. Sowe have a number of Bechstein's
and barbastelle tree roots here.
And we will be deploying thosetrail cameras to see if we can
improve and refine that approachand and hopefully see that begin
to roll out and improve ourservice for bats in trees. The
second strand is then moving thenext step, which is the really
(05:30):
exciting step, which is can wecreate that roost in trees by
wounding them in deliberateways. And this is something that
various people have tried for anumber of years, I believe. And
I think the the main limitationwith previous work is that it's
just not been monitored. Andthat's because it's very, very
difficult to establish whetherbats are using a tree. So we
(05:50):
have the two elements of theproject really coming together
that we will create thesefeatures. And the design of
those is very much guided by thedata from the battery habitat
key. And then once we havecreated them, we'll be in a
position where we can use thetrail cameras to establish
whether they're used, andhopefully, they're used by the
species that we intended to beused by. So one of the strands
of the project is to look at thetemperature and humidity
(06:14):
regimes, both in naturalfeatures, the features that we
create, and we are in Danielswood at the moment, because we
are going to put some dataloggers in bat boxes to see how
they compare.
Steve Roe (06:25):
I think last time you came on, I accused you of
trashing trees. And then sincethen, we've had Vikki Bengtsson
on the podcast and she talksabout the project she's been
doing both here in the UK andacross Europe. And the results
from that a pretty spectacularreally so it's nice to see
somebody else's taken on here inthe UK, the data loggers you've
got so they're their dataloggers, the are familiar to
(06:46):
people who do that work. Andtypically they go in caves and
roost sites. How are you fixingthem into that boxes today?
Unknown (06:54):
Good question. Not really sure. The flat Schweglers
have a section of wood at theback. So we will screw a small
screw in that and then hang themfrom a piece of wire. I think
for the rain Schweglers I'llhave to settle for just resting
them at the bottom of the boxand hope that that's gives us
some data. I admit that that'snot where the bats will
(07:14):
necessarily be roosting but itwill give us some comparison, at
least for an empty bat box andan empty cavity. Yeah, great
stuff. Vikki was my boss at theancient tree forum. Yeah, so
that's my first box and theancient tree forum and she's
inspirational. Think we so thisproject actually came from
(07:34):
working with Vikki on a Europeanproject called vet search where
we were developing acertification scheme for veteran
tree management. And I've kindof had this realisation that we
do fantastic work in ecology, wedo fantastic work with bats, and
typically we scrimp and save andtry to find the money to do the
work. And I was delivering atraining course with Vikki. And
(07:54):
she basically flipped that onhis head and said that through
the years she worked inconservation, they will find
money here, they will scrimp andsave and try and get what they,
they need to do an okay job. Andactually, we do fantastic work,
just need to sell it better. Sowe need to say, this is valuable
for this reason. And it's worththis much. And therefore I want
(08:15):
this money, we should be goingafter the big fingers really.
And it's about asking for whatwe need rather than what we
think we will get away with. Andso that inspired me, Vicki and I
then were delivering anothertraining course in Finland, we
were sat in a bar discussingvarious projects and her work.
And that's where the embryo ofthis project was born. And so I
(08:37):
came back from Finland andwithin three weeks, the people's
trust for endangered species hadtheir current round of grant
closing was finishing, that didnot make any sense. Within three
weeks, the people's trust forendangered species had a
deadline for one of the grantapplications. So I submitted and
here we are. Now I need to focuson this because otherwise I
(09:02):
won't run out of battery why isthis tablet not working
Steve Roe (09:11):
So Jim, we finished putting out the data loggers in
Daniel's would come down to thebottom of the fields. And we can
tell we're a lot closer to themotorway. And we can hear bits
and pieces of chainsaw noise inthe background. What are the
guys and the trees down heredoing?
Unknown (09:24):
So they are working on the trees that will be used for
creating the bat roosts. So thefirst step is to remove the top
of the tree. And that's becausewe are cutting features into
tree and we're worried aboutpotential failure through
torsional loading. So twistingmotion of the tree. So that's
step one. So we have four orfive people down there at the
moment, just taking the top setof trees. Then the next step we
(09:47):
will be looking at actuallycutting the features into the
trees themselves. So we have twospecies we're catering for.
We're looking creating roots forBecstein's and barbastelle and
for each species, we are tryingwhat we're calling instant
roosts and future roosts. So theinstant roosts, as the name
would suggest, suitable oncethey are cut effectively, it's a
(10:10):
bat box in a living tree. Andthis is similar to a lot of
other work that's been going onpreviously, if cutting slits,
etc, they are perhaps slightlymore tailored to the individual
species roosting requirements,that the idea is that yeah,
we'll take a section of tree outkind of a wedge from the front,
we take the back off of it, wecut an entrance into it, and
(10:30):
then we reinsert that lid,effectively, the future roosts
where we are cutting wounds intothe tree with the idea of
anticipating how the tree willrespond and how it will grow
after the wounding. So work fromVikki Bengston, who you
mentioned earlier, she has anest box designed to the
(10:51):
incident routes is very muchlike the nest box designed but
it's it's tailored for bats. Herwork has shown that after maybe
five or so years, the lead getsbasically spat back out of the
tree, as if the tree isrejecting it. Because it's no
longer living, it's no longerpart of that tree. So in
conservation, we're looking athaving various tools, and one of
them might be an instantprovision. But also we're
looking at longer termprovisions as well. So the
(11:13):
future roosts are doing justthat. So we cut features into
the tree, they're open to beginwith. As the trees continue to
grow, they will callus over. Andthey will close over entirely.
So effectively, what we shouldend up with something is very
similar to a natural featuresthat's covered in living
functional wood. So we havewater moving through that word,
it means that the temperaturehumidity regime should be as
(11:35):
close as possible to livingtrees as natural features as
possible.
Steve Roe (11:39):
And why are these better than bat boxes?
Jim Mullholland (11:42):
We don't know at the moment is the question.
So we are experimenting, I guesswe are looking at can we
increase the size of ourtoolbox. And this is something
that Vicki talks about as wellthat they will not be suitable
in all situations. We haveselected trees here with the
foresters that are of loweconomic value and low
ecological value. So they wouldhave heard of or otherwise been
removed. And it's all aboutexpanding the size of the
(12:04):
toolbox. We know that that boxeshave their place. But we also
know from studies that thetemperature and humidity regimes
are not as good or not the same,at least as natural cavities.
And the concern there is thatthe individuals that use them,
especially if they're breeding,perhaps will be less healthy if
they're less healthy, or they'regiving birth to young that are
(12:24):
less healthy, and well that havea knock on effect to the
populations year on year onyear. So it's increasing the
size of the toolbox.
Steve Roe (12:34):
Right, we're going to head down the hill and on top
some of the top guys were makinga lot of noise
Jim Mullholland (12:39):
they are it's getting smoky here as well
Steve Roe (12:43):
sort of comes down the bottom field and we're now
in fairly steep woodland, and wecan see the traffic on the M5
motorway. There's a guys makinga lot of noise up a tree. Taking
the top of the tree out like itwas
Unknown (12:59):
probably 15/20 metres up the tree. It's raining
sawdust.
Steve Roe (13:04):
Once you taken the top out of this tree where
abouts on the tree is he makingthis cut? making
Unknown (13:07):
the call, we will be creating them between five and
10 metres on the main stem. Sowe're focusing all of the
features on main stem we chosefive to 10 metres because that's
what the data from the bat treehabitat key says that we should
do. Basically it talks about thehighest proportion of maaternity
roosts recorded the trees are inthat region. That could be down
(13:28):
to bias in data. But obviouslywe know that there's probably a
preference to roost at a certainheight so below five metres is
probably unsuitable and higherthan that potentially gets less
suitable as well because thebats experience more movements
in the wind, etc.
Steve Roe (13:43):
It's not a very dense woodlands. It's quite windy
about the winds. Quite quickly.
Do you know that there are barbsand Bechstein's in this bit of
woodlands or is this an areayou've not surveyed yet.
Unknown (13:52):
So we're in Daniels wood still we're at the other
end of Daniels word and the topend of Daniels words is in a U
shape so overall the woodlandstend to be in a Y shape. If you
mentioned sticking the the southend on bottom. We are basically
the furthest north you can goand the furthest west you can go
right next to the M5. TheBechstein's pretty much all
(14:13):
roosted within Daniel's wood,albeit slightly further south
than where we are. There is onetree roost that's, maybe 300 400
metres from here Bechstein'sbats. The barbastelles however,
they do use the woodland and Icatch them on the rides in The
Woodlands on the other sidewhere we just were looking at
the bat boxes. But to myknowledge, they don't roost in
this woodland so they roostfurther south from here they
(14:35):
roost further north from here,but I haven't yet recorded any
barbastelle roosting in thiswoodland. The trees we selected
we have three sites on theestates for creating these
features. We have Daniel's woodwhere we are now. Next week, we
will be working in a regioncalled Hawkers Grove, which is
further south and then we willbe finishing off by one of the
legs. And so we kind of spannorth to south maybe about two
(15:00):
kilometres between the threeareas. And that encompasses more
of the areas where thebarbastelle roosts are.
Steve Roe (15:07):
And what are the what are the tree species? When
you're targeting? Are youtargeting particular species for
the two different species ofbats? Are you just trying to
connect with them,
Unknown (15:15):
I'm less worried about individual tree species,
especially for the instantroosts. Because we're not
waiting on any decay processes.
We're not waiting on the treesto respond. We're essentially
creating bat boxes and livingtrees, it would have been nice
to use just one tree species forconsistency. However, I had to
go with what the foresterprovided me with essentially. So
(15:36):
we have a mixture. And it's amixture of oak mixture of ash,
sweet chestnut, and somesycamore as well, it depends.
The makeup of individual treespecies varies through the three
different woodlands that we'reworking within Ash is going to
be an interesting tree species.
(15:56):
The forest, as you can imagine,was very happy to give me all
the ash trees that I wanted. ButI limited in the number that
we're using just throughconcerns over the longevity and
future stability. I'm stillhappy to create them in them, I
think it will be a usefulexperiment. There's lots of talk
about at the moment about whatwe are going to do with ash
(16:18):
trees. First of all, the hope isthat we won't lose all the of
the ash trees. Second of all,there will be some that will
contract ash dieback but surviveso they kind of get it and come
out the other end. Okay. We knowthat trees that are in the more
natural setting, more diverseecosystems are more likely to be
resilience to as diverse and sowe're in at least in Daniels
(16:41):
wood, we're in an area ofancient semi natural woodland,
some fantastic ground floraaround us at the moment. So the
soil ecosystem here should befairly healthy. This section
we're in now is a nonintervention area, with the
exception of what we're doingclearly. So yeah, I'm cautiously
optimistic about our ash diebackhere, however, it is inevitably
(17:01):
going to have an impact.
Steve Roe (17:03):
Yeah, I mean, you say the grand falls nice. I mean,
you can't actually see much soilat all you've got bluebells
starting to poke through thecarpet of dogs mercury, there's
some wild garlic starting. Sothe smell of thats drifting down
the hill. Yes, nice woodanemonie as well.
Unknown (17:20):
Okay looks liek the final guy has come down. It's
teatime!
Steve Roe (17:25):
So after a tea break from taking the weight out of
the top of the canopy, we joinMark back at the tree where he's
now going to create the actualfeature for Bechstein's on the
trunk. So the feature that'sMark here is that to make say,
an instant feature, so it's likecreating a what essentially a
bat box would do within anatural tree feature. So they're
cutting a long rectangular blockof wood out of the main stem of
(17:50):
the tree, the tree trunk, andthen they're cutting in from
behind to release the back ofit. And that's been released and
lowered down to the ground and achunk of that shaved off so that
when it's placed back in themainstem and put in place with
nails or screws, there's anatural cavity then then created
and that's what Mark is about tocreate. So Mark was just telling
(18:14):
me that he's been an arboristfor about the last 20 years. Is
this the first time you've donethis sort of work on this? For
this reason?
Mark (18:21):
Yes, bat roost creation like this. I've done coronet
cups. I've done all boring holesfor the birds and stuff like
this. But yeah, specificallythis precise A bat roost habitat
creation and that sort of stuff.
I've done various surveying forbats looking for them in holes
in trees, but actually creatingscratches. First time I've been
Steve Roe (18:39):
Watching Sean there do it on the ground look fairly
straightforward. How complicatedis it being stuck in a harness
on a rope?
Mark (18:45):
it's a little bit trickier because you're using the tip of
the bar and you've got tobalance it and it's not. It's
not the sort of cutting you makeon a daily basis. It's not the
sort of thing you do when you'repruning branches are cutting
chunks off. So it's slightlydifferent. On the day to day as
an arborist have a it's the sametechniques, it's using the sword
same way but it's just slightlydifferent to how you do it.
Steve Roe (19:06):
I'll let you get on with it. You don't see Claire
Balding doing this on herpodcast I'll tell you that much!
So this is a BatChat first I'm10 metres off the ground in a
harness and I'm next to Markwho's got a chainsaw in his
hands so Mark just describe whatyou're about to do.
Unknown (19:25):
I'm about to cut a big slot, either side of this oak
tree 1.3 metres long down thetree about 10 centimetres wide.
We're going to remove that slotlower it from the ground, cut
the back off it to createhabitat for neck stones habitat.
(19:45):
So yes, I'm going to make twoparallel longitudinal cuts down
the stem of the tree bout 15centimetres deep to measure my
chainsaw to work out with 15centimetres a lot easier.
Steve Roe (20:29):
So you can hear Mark is now making the final cut
around the side of the tree justto the left of where he's made
the front cuts and that willrelease a metre long piece of
wood along the length of thetrunk which will be lowered down
to the ground we worked on thetrusses nice and clean himself a
(20:51):
nice little comfy position nowset on the branch halfway up the
tree. And as I'm still to watchhim now there's a whole range of
orange florescent jacketsthrough the woodlands some of
them halfway up trees some ofthem on the ground as the team
works on four trees around us.
(21:17):
The thumping noise is Mark hidin the piece that he's cut with
the back of his hook, which he'sgoing to use
Mark's having to go around theright hand side of the piece
because the branch that he wassat on earlier, is now in the
way of where he needs to makethe cut. And the cut that's been
(21:40):
made is facing south and it's anoak tree. There's probably about
20 metres high and the cut'sbeing made it around eight to 10
metres up and there's no lowerlens on there. So true. Please
get it in the bottom now it'slooking quite carefully and he's
got to the now. Now it's timefor the final test with the axe
(22:01):
and there's one resistant bit inthe middle which is just not
going to be released easily
Unknown (22:06):
At the top have you gone up above the opening?
Steve Roe (22:24):
So Jim just described the feature on the tree behind
the one that Mark's working onthis is for barbastelles.
Unknown (22:31):
So Will's creating one of the future roofs, it's
essentially just a long slit inthe face of the tree. And the
idea there is that we create asplit or crack type feature we
created a slightly wider openingand it's tree continues to grow
and callus around the wounditself. It covers over the
(22:53):
majority of it and just leavesthe small opening
Steve Roe (22:58):
Mark now it's just lowering this metre long block
of wood that is cut out fromfrom the tree he's been working
on. The piece is now on theground with Jim and Mark is just
coming down.
Jim Mullholland (23:11):
I have aweird hobby!
Steve Roe (23:20):
So as the features are being brought down, they're
being piled in the middle of thewood for everyone to work on. So
the team have just been makingcuts on the two metre long
sections one for barbastelle andone for Bechstein's and Mark is
(23:42):
heading up the tree now to thecavities currently got there to
place the data logger and thetop which is where hopefully the
bats will be roosting and thenthe metre long session will be
censored so it can be screwed inplace
(24:04):
so Jim is now attaching themetre long session to Mark's
rope which is now getting hauledup. So in the front of Mark's,
block of wood which is goingback in place there are two
vertical slips which have beencut to 40 centimetres from the
(24:25):
top and bottom and on theadjacent tree. The block has had
a artificial woodpecker holedrilled in using the battery
powered electric drill.
Woodpecker holes been designedfor Bechstein's and the two
slits on mastery here designedfor barbastelle
Jim Mullholland (24:46):
It's one tree per day per person.
Steve Roe (24:48):
So this is first time the team have done this and we
met at 10 o'clock this morningand it's now getting on for four
o'clock but Jim hopes that aspeople return to the site and
repeat the same process forother trees that the process
will become faster. So Mark isnow attaching the datalogger to
the top of the feature.
And that's it, the piece is backin place there's four screws
(25:20):
then holding it in place.
and thanks to Jim for having mealong for the day. And thank you
to you for listening to thisepisode. I hope you've enjoyed
it. If you take a look at theshow notes, you'll find links to
Jim's social media and our otherepisodes on this subject. Now
this series we are running backchats first ever competition.
(25:42):
children's authors Emma Reynoldsand Angela Mills have kindly
donated prizes. Angela hasdonated a copy of Bobby the
brown long-eared bat signed byboth Angela and Chris Packham,
and Emma has donated a copy ofher newly released book Amara
and the bats. To enter thecompetition to win one of these
brilliant books. All you have todo is write as a review about
this podcast BatChat. And thetwo winners will be picked at
(26:03):
random at the end of the series.
So there's only a few weeks leftto do this. Not all podcast apps
allow you to leave reviews soyou can find instructions in the
show notes of this episode. Andplease note that we're only able
to post prizes to addresses inthe United Kingdom. The series
continues in two weeks time withthe author of Bobby Brown on
good bat, Angela mills. So untilthen, I'll leave you with a clip
of that next episode. I'll seeyou then.
Angela Mills (26:27):
You know, Chris Packham did the foreword, which
is always lovely. And Kate doessome lovely illustrations. So as
my first attempt, I think it'sbeen a pretty good attempt when
I go into schools and read thebook. You know, the kids are so
enthusiastic, and I even had onelittle boy say to me once, this
is the best day of my life, andI thought, Wow, that's amazing.
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