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.

New Lab Publication

It was recently demonstrated that shorebirds (godwits) fly non-stop between Alaska and New Zealand on their autumn migration - a flight that takes more than a week! Do we need to revise our current flight models as a result of these observations? How did such long flights evolve? These, and other questions are discussed in an "unsolved mystery" piece in the May issue of PLoS Biology: http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1000362

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.