|Posted by Aaron Corcoran on August 19, 2013 at 4:00 PM|
The largest-ever gathering of bat biologists occurred last week in San Jose, Costa Rica at the joint meeting of the 16th International Bat Research Conference and 43rd North American Symposium for Bat Research, with 639 people from 55 countries attending, and I was fortunate enough to be present.
There was some wonderful conservation-minded research on white-nosed syndrome and bat mortalities caused by wind turbines. It's becoming increasingly clear that Pseudogynoascus destuctans (the cause of WNS, formerly Geomyces destructans) is an invasive exotic species brought over from Europe by humans. Pd is widespread in Europe and bats there do not show the mass mortality seen in the US and Canada. Sebastian Puechmaille from University College Dublin presented work modeling the habitat occupied by Pd in Europe and used those models to predict where Pd might occur in North America. The sad news is that we should expect it to eventually cover most of the northern half of the US and nearly all of Canada. People are still nowhere near a real solution to one of the biggest wildlife disease epidemics ever reported.
As for wind turbines, people are starting to find ways that turbines can coexist with bats, at least with fewer mortalities than we have seen. Michael Schirmacher from Bat Conservation International presented a summary of around ten studies that have tested whether you can limit bat mortalities by not running wind turbines at low wind speeds, when bat deaths are most common, and energy production is low. All studies found a reduction of mortality, with most showing 50% or fewer deaths at a cost to the companies of only 1% of their profits or less. Now we just need wind companies to start implementing these strategies, something that may require legislation to happen (imo).
A presentation at IBRC 2013
I was most excited to see the 20 or so studies that related to bat echolocation. Here are some of my favorites.
Arjan Boonman from Tel-Aviv University, Israel has documented multiple unrelated species of fruit bats (Pteropodids, also called flying foxes) that apparently echolocate. While all micro-bats echolocate, it was thought that only one genus of mega-bats echolocate. However this work hints that all bats may use sound for sensing the environment, and the type of echolocation used by fruit bats -- tongue clicking -- may have evolved first, as it is simpler to use. This work, when fleshed out, has the potential to dramatically change our understanding of echolocation in bats.
Klemen Koseij from the Max Planck Institute of Ornithology in Germany provided compelling evidence that bats are able to use echoes from sounds made by other nearby echolocation bats to detect objects. It's been shown by other researchers that big brown bats competing for food in captivity sometimes go silent while following other bats. But are they simply localizing the sounds of the bat they are following or are they also able to get information from the other bat's echoes? Klemen devised a clever experiment to test this involving placing two bats in a square-shaped bat race track. When the leading bat turned one of the corners and tripped a light sensor, Klemen made it such that an object (a frisbee actually) was triggered to move rapidly over a short distance towards the leading bat. This caused the bat to turn sharply away from the object. The interesting part, however, was what the trailing bat did. It too maneuvered away from the object, even though it was trailing around the corner and likely could not see or echolocate the frisbee. Klemen reasoned that the only way the trailing bat could detect the object was by hearing an echo from the sound the leading bat made that reflected off the moving frisbee. If confirmed, this study demonstrates a previously unknown ability in echolocation animals.
Friends wearing bat noseleafs at the banquet
Advancements in technology have brought about a revolution in bat studies over the last ten to fifteen years. Yossi Yovel, also of Tel-Aviv University, proved that those advancements are continuing by being the first to put an ultrasound microphone that records to a data card and a GPS on a free-flying 30-gram bat. This allowed him to make all-night recordings of bat echolocation emissions and tracks of their flights as they foraged, interacted with other bats, and searched for insects. The possible applications of this technology are sure to open many windows into the amazing capabilities of bats.
Finally, I was very impressed by Caroline and Michael Schoner's presentations (Ernst-Moritz-Arndt University, Germany) on the symbiotic relationship between Harwike's wooly bat and the pitcher plant Nepenthes hemsleyana. This pitcher plant has evolved mechanisms to attract Harwicke's wooly bat to roost in its "pitcher", thereby providing good conditions for the bat to roost (as detailed by Caroline) in exchange for nutrient-rich bat guano. This pitcher plant has evolved to reflect a distinctive echo to the bat from a structure just above the pitcher. When Michael experimentally modified this structure to make it reflect stronger or weaker echoes, bats were not attracted to roost in the modified plants, but instead the unmodified plants with their charachteristic echo (which Micahel was able to characterize with a robotic echo-locating machine). These studies and many others at the conference continue to show how intricately bats are connected to ecosystems and the many benefits they provide.
This conference was extremely gratifying to me both personally and professionally. I met several biologists whose work I strongly admire and cemented dozens of relationships with colleagues that I've met over the years. When I multiply my experience, the knowledge I gained and relations developed by 639 I gain a true appreciation of what was accomplished at this meeting.