New research on bats

During this week two interesting papers on bat biology have been published. First, McGuire et al (J. Anim. Ecol. doi: 10.1111/j.1365-2656.2011.01012.x) reports on radio tracked silver-haired bats at Long Point Bird Observatory, Ontario, Canada, Radio tagged birds were tracked using 5 towers with antennas. Most bats stopped over for 1-2 days before continuing migration, while some bats stayed for up to two weeks. Another paper, by Elemans et al (Science, Vol. 333: 1885-1888) reports about ultra-fast laryngeal muscles, which can produce echolocation calls at rates beyond 160 calls per second. Bats use such fast repetition rates during their final approach to a prey, calls known as feeding buzzes that are heard in a bat detector.

Animal Flight Lab on Bat Conference, Prague

Members of the Animal Flight Lab are currently attending the 15^th International Bat Research Conference in Prague. This is the main outlet for bat science, being the biggest assemblage of bat scientists ever at 550 individuals. In the afternoon on Monday (23 August) we had the flight symposium, organised by Anders H and Sharon Swartz, Brown University. Members of both the Lund and Brown labs gave excellent presentations, showing how kinematics and PIV data could be used to get lots of information (Florian Muijres and Rhea von Busse). Other talks were on flight mechanical constraints on bat size (Ulla Lindhe Norberg), context-dependent flight speeds (Marc Holderied), energetics by Na-Bicarbonate isotope analysis (Christian Voigt), and muscle and tendon morphology in the wings (Sharon Swartz). In the evening, the whole group of speakers went in to Prague for a excellent dinner at a restaurant (Café du Paris, see picture). After dinner we strolled through central Prague and into the old city. Today (Tuesday, 24 August) we have enjoyed many more interesting talks, and soon we will attend the poster session, where Melanie Stuiver will present her poster on the bat robot (RoBat).

Rabies in Swedish bats

Bats can get infected about a form of rabies (Lyssa virus), which rarely also can be transferred to other mammals, including Homo sapiens. Out of four fatal cases in Europe during the last few decades two have been bat researchers, so there is a small risk of handling wild bats in Europe. However, Sweden has thus far been without any reported cases of rabid bats. But new samples taken during 2009 in Skåne found antibodies against bat rabies in eight Daubenton's bats (Myotis daubentoni), according to a press release yesterday. These bats are non-migratory (at least we think so), and therefore they should have been in contact with actually sick bats at some stage. Hence, Sweden is no longer a rabies-free territory. But this is a fully expected result considering that rabies is found in our neighboring countries Denmark and Finland, and is common in Germany and Poland. Since many bats migrate to continental Europe it would have been strange if infected bats never turned up in Sweden. This new finding does not change any of the official recommendations for us working with bats, which include being vaccinated and wearing a glove when handling (such as ringing) bats. More information can be found at www.naturvardsverket.se/fladdermus .

To stay or to go?

Especially during a winter like this those birds that migrated south last autumn probably did a good choice in a Darwinian sense. In mild winters, however, those that decide to stay near their breeding areas may be at an advantage because they can select territories first and they don't have to pay the cost of migrating. Many bats have evolved the alternative strategy of hibernating, which means that they lower their body temperature almost to the ambient, and therefore they spend very little energy. But there is an energy cost and the fat they accumulate in the autumn must last until spring, when insects emerge again. In that sense they can be compared with bird migrants, but instead of converting fuel into distance, they migrate in time. In bats, there are species that do migrate, often in combination with hibernation at the winter destination, and we may think about how this strategy came to be? Here, I want to share some images from a recent winter bat count in the mine at Taberg, Småland. Six species were encountered, and here are pictures (lower) of Whiskered bat (Myotis mystacinus; the two small ones) and Brandt's bat (M. brandtii; the two larger ones on the right), and the picture on top shows a Natterer's bat (M. nattereri), which is quite a rare species in Sweden.