The Baltic workshop was held from 16 - 21 May 2001 in the village Plateliai, in the north west of Lithuania. Setting was the beautiful undulating landscape with lakes and forests of Zemaitija (lowland) National Park. A feast of corncrakes, beavers and nightingales. Here lodgings and meeting rooms were made available through co-operation from the National Park Management and the Lithuanian government. Here a performance of singing and dancing by a local folk group, who made us all join in their dances, made us feel welcome immediately. Dainius Pauza and Neringa Pauziene did most of the hard work in preparation and the main organisation in Lithuania. Matti Masing (Estonia) and Gunars Petersons (Latvia) arranged participants and support from their countries. Participants from Lithuania (8), Latvia (4), Estonia (5), Finland (2) and the Netherlands (2) made it to a real international event. Peter Lina accompanied me to workshop in Lithuania and, as chairman of the Eurobats Advisory Committee, used the opportunity to visit the Ministries responsible for nature conservation in Lithuania, Estonia and Latvia to discuss their accession to the Eurobats Agreement.

On the first day after our arrival in Vilnius, on our way to the west, we had a stop at Kaunas. On this evening Dainius, Peter and myself had a short excursion to a small estate south east of Kaunas, as well as to the river Nemunas running through Kaunas. In the estate Nathusius' pipistrelles (Pipistrellus nathusii), Pipistrelles (P. pipistrellus), some Serotines (Eptesicus serotinus) and distant Noctules (Nyctalus noctula) were picked up by our detectors. Just a couple of Myotis bats were heard, which were probably Daubenton's bats (Myotis daubentonii) on their way to the ponds on the estate or the nearby river. Interested in the possible occurrence of Pond bats we spend most time on the river bank on several spots. We didn't find Pond bats, but heard quite a few Daubenton's bats, Nathusius' pipistrelles, with typical QCF-frequencies on 35 kHz, and Serotines hunting along the river bank and again Noctules high up in the air.

On the next day we continued our journey west along the Nemunas, enjoying the river landscape with wild river banks, isles and stretches of nice floodplain forest in the plain and wooded sandy hills on the higher terraces. Here many old estates and castle hills were situated. A very batty landscape we had to leave behind us.

In the evening we arrived in Plateliai in Zemaitija National Park, where group by group all participants gathered. After the dancing most of us had thrown of the fatigue from the journey and we had a first evening in the park surrounding the buildings. Enormous activity of hunting Noctules low above forest glades, and of Pipistrelles and Nathusius' pipistrelles almost everywhere in the park, made everybody enjoy the new detectors which I was able to bring to the workshop. Moving from the shelter of the park, to the open landscape around lake Plateliai, treated us on clear visual and auditive observations of hunting Northern bats (Eptesicus nilssonii). A beautiful illustration to the theoretical information on similarities and differences in size, flight style and sounds that was going to be topic of discussion in the following days. Nightingales and calling corncrakes completed the concert. In our journey from Kaunas to Plateliai we had crossed the distribution border of the two Eptesicus species. We would not find Serotines anywhere around Plateliai.

On the open bank of the lake, again some Northern bats were heard and seen passing, as well as
Nathusius pipistrelles and distant Daubenton's. Since everybody had travelled long distances we
returned for a good nights sleep at about midnight.

On the next afternoon the theoretical introduction to the survey and identification of bats with ultrasound detectors commenced. In slides, transparencies and sound examples, a large amount of information on sound and flight physics and bat biology, as well as information on observational skills and handling of detectors was going to be processed to set the basis for observation and identification in the field.

In the meanwhile temperatures had dropped considerably and a strong wind was developing. We
therefore decided to start the evening in the sheltered landscape of a park of one of the many estates in and around the National Park. It proved to be a good choice to go for Renavas Estate, of which two keepers also attended the workshop. Again a marvellous flight and sound show by Noctules above the ponds, and Nathusius and common pipistrelles on the bank. Such a setting at sundown is always beautiful.

With growing darkness Myotis bats started passing us. Daubenton's heading for the pond and little
stream. And Noctules flying back into the forest again in approximately the same direction as where the Daubenton's were coming from. Some of us tried to follow these flight paths, but soon were distracted from that task by whiskered/Brandt's (Myotis mystacinus/brandtii) bats hunting in openings between the tree crowns. Since in hibernation sites, netting and findings whiskered bats are almost never found in Lithuania, we could assume they where Brandt's bats. Everybody spend a lot of time recording them, watching them and studying their flight behaviour.

Although it was rather cold, the wind settled a little and we decided to go for a lake on the river Varduva south east of Renavas. Here on the relatively open bank with scattered trees huge numbers of Northern bats were heard. They made a spectacular noise almost masking the Nathusius' pipistrelles and high flying Noctules. In fact analysis of recordings on a laptop in the field by Dainius first drew our attention to the presence of the Nathusius pipistrelles.

Since it was well after midnight and we didn't have a break yet, we returned for Renavas manor house were most of us went for the fireplace. A couple of us however tried the park and forest directly surrounding the manor house. Here excellent observations and recordings of Natterer's bats (Myotis nattereri) were our reward.

After the break we went for Plinkses park at Plinkses lake. Walking down the road towards the lake
we stopped a little bit to listen for the distant sound of some Bittern. Immediately some Daubenton's flew over our heads heading for the park. I got everybody to watch this phenomena: a flight path of Daubenton's and then we started following them. After fooling us a couple of times with clear swarming near a tree – exited shouting: "... this is the roost tree...come over an have a look at it..." - and suddenly disappearing again, we found the tree in which they really had their roost for that day. An old and very high lime tree just like all the others where swarming had occurred. Nice result: a tree roost in the first night!

While the hunt for the tree was going on, some had checked the lake and observed hunting Noctules, Nathusius' pipistrelles, and Daubenton's leaving the water over an open sandy beach and heading for the tree lane in which the other party later found the roost.

During the following day the weather grew colder and more windy. On the cost a storm was developing. So again in the evening we headed for the shelter of an estate park. In the park we selected, Sateikiai park, there was not much wind, but it was cold. Nonetheless bat activity in the park was high in about the first hour and a half after sunset. We found Northern bats above the glades and on the edges of the park, Pipistrelle and Nathusius' pipistrelle bats, a flight path of Daubenton's leaving the park towards ponds and lakes outside, and also head good opportunities to listen to and see hunting Brandt's bats and Natterer's bats. No Noctules.
On our way to a very old natural mixed forest stand near lake Plateliai we stopped at a church where Nathusius pipistrelles and an occasional Northern bat passed. The night grew colder and colder. In the Forest stand roosts of Long-eared bats (Plecotus auritus) were known. We hoped to be able to demonstrate the species here and make recordings. Part of the group went into the forest and indeed heard the fast and very silent rhythm of the Long-eared bats. Something different from any other sounds we had heard so far. The group that stayed on the open forest road was lucky too. They recorded Long-eared bats in their relatively loud sonar mode with a little QFC on 12 to 15 kHz.

Next we started visiting the bank of lake Plateliai on different locations, as well as some other smaller lakes around the larger lake. We kept on hoping to find the Pond bat. But in the strong and cold wind we never heard anything else but Northern bats, which are certainly capable of coping with this northern climate, and Nathusius' pipistrelles. On one sheltered site we observed a lonely Daubenton's.

At returning to our home base some of us still had the energy to go for the swarming period in the
forest of Plateliai park. The air was roaring with Nathusius' pipistrelles and somewhat less Pipistrelles. The latter headed off for the village, but our energy was not enough to follow them. On this and previous occasions discussions arose on the frequencies of the Nathusius' pipistrelles. I am used to Nathusius pipistrelles QCF-frequencies below 40 kHz and down to 35 kHz in the open landscape. Here we regularly observed animals on 40 to 42 kHz (Pipistrelles in closed environment??) while at the same time we heard the unmistakable two syllable social calls of Nathusius. For Dainius, Gunars and Matti this was a normal phenomena. But sometimes, not always there were also Pipistrellus pipistrellus around. So how to explain this? Wise thing to do is to go back to catching and marking and recording the sounds of hand identified Nathusius pipistrelles in this part, and other parts of Europe. This would help us in deciding what to do with these animals with QCF-frequencies between 38/39 and 41/42 kHz. Also strange was that, although we tried, we did not find any 55 kHz Pipistrellus pygmaeus..

On the next day the weather certainly did not get better. So in the evening part of us used the time to analyse time expansion recordings made on the previous night, while another party made a short excursion to the bank of lake Plateliai. Here in the cover of the forest on the bank Long-eared bats were heard, and in less sheltered habitats Northern bats, Noctules, Nathusius' pipistrelles. On the water of the lake Daubenton's and animals who very well could be Pond bats.

On the next day we had our round up discussions on the workshop and everybody started to leave again. Although leaving is always a little sad, spirits were high concerning the plans for field work 'at home'. I am curious regarding everybody's results.

Peter Lina left together with Matti and other participants from Estonia. With Dainius and Neringa as my hosts, we started travelling to the south-east to Kaunas again. In the evening we stopped at two estates north of Kaunas. In the first in Baisogala we observed Pipistrelles and Nathusius pipistrelles and some faint to short to identify Myotis bats. Soon it got pretty cold and activity dropped to zero. Not even a single Daubenton's on the ponds. Stubborn like we were we nonetheless tried the next estate. Here, to our surprise, activity was very high. Pipistrelles, Nathusius pipistrelles and Daubenton's bats were having a party above the ponds and a canal surrounding the main building. And fantastic recordings were made of social calls from Noctules, Long-eared bats and Nathusius pipistrelles calling from trees. This must be a spectacular mating site in autumn.

On the next day we visited Dzukijos National Park in the south east of Lithuania. Beautiful landscape with large forest areas and raised bogs. Fantastic landscapes and vegetation, and beautifully conserved old villages. Later on, the same story again: pretty cold in the evening. But we tried anyway and did find the hardy species. Nathusius' pipistrelles, some Northern bats and some Daubenton's passing at high speed on the roads, probably on their way to nearby water, and Daubenton's and the other species hunting on the river. Then, like it or not, we simply had to stop because Kaunas and Vilnius were still a long drive away and I had to get to the airport early next morning.

Herman Limpens

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