Wednesday, July 30, 2008

Buh-bye Lava Beds, hello caribbean

Silver-haired bat Originally uploaded by
Sadly the fun is over at the BCI acoustic monitoring class and I'm back in San Francisco. After about 12 hours of sleep I feel almost normal. Our last night batting at Lava Beds was such a delight. We were in an area where the Ponderosa pine forest was beginning, so there were lots of trees but still some sage scrub between the groups of trees. The weather was cool but not cold and the skies full of stars. After exploring the area, we all stood in a clearing between the trees as the bats were released one by one with their tiny glow sticks. Many were very cooperative, hanging around to give us lots of great recordings. Some even returned, so there were sometimes two or three little magical fairy lights dancing among the treetops. Altogether for the class we had about 12 different species of bats and one of the star attractions was this darling little Silver-haired bat (Lasionycteris noctivagans) whose voice is way bigger than its size would lead you to believe. Tonight I leave for my next adventure, doing a survey of bats on two caribbean islands, St. Lucia and Montserrat. I'll post an update after my return.

Monday, July 28, 2008

At the ice cave

At the ice cave Originally uploaded by
Another late night last night -- we didn't get back to the lodge until 2:30am. Last night we looked for bats in Modoc national forest, quite a different habitat from the past few nights. As a result we got different bats, more on that later. This morning I got a chance to sit down with one of the instructors and get help with analysis of my thesis data, e.g. figuring out what kinds of bats are in the city. It was great to finally get answers to my questions and tips for how to do what Joe called "forensic bat call analysis".

Sunday, July 27, 2008


I've been writing about the process of capturing bats so that we can record their calls for our reference libraries. There are a few different ways to release the bats. The simplest is to simply let the bat fly out of your hand. With practice you can shine a spotlight on the bat as it flies away, and hope that it will circle around so that you can record it as it passes. It's important that you keep track of the bat, so that you can know for sure what kind of bat made the call you just recorded. If you're not so good with the spotlight, you can also attach a very small light stick to the bat's belly. We use the kind of glue that's safe for kids to eat, since the bat will groom it off fairly quickly. Here you can see a light stick getting glued to the belly of a Mexican Freetail bat. The trick here is to hold the bat very gently so it doesn't feel like it has to struggle. To release the bat, you simply hold it in your hand and raise your arm up. If the bat is warm enough (and it should be if you kept it in your jacket), it will fly away after a moment. All you can see is the tiny light flying away. Sometimes they stick around, circling around the bushes and weaving in and out of the tree tops. It's magical to watch them like fireflies or Tinkerbell.

Where the bat bags are

In my last post I mentioned that after the bats are captured in mist nets, we figure out what species they are, and then they go into small cloth bags. Most of them seem to settle down and rest in the bags. When there are lots of bats coming into the nets, then a single bag can contain up to a half-dozen bats. Then the bat bags go inside someone's jacket to keep them toasty warm. Here you can see Dylan in his job as bat bag repository. This is a very cool job, but sometimes has its drawbacks. For example, some species have a strong musky odor. Or sometimes the bats pee or poop in their bags. Then you get a pungent souvenir of the evening that hopefully won't last longer than the next laundry day. Alternatively, sometimes the bats in the bag are very active, or even agitated. Last night for awhile I held a bag of Big Brown bats against my chest in my sweater. Big browns are famous for being feisty. They tried to bite me through the bag and every once in awhile would chatter and squirm. When I held my hand over them with gentle pressure they calmed down and were just a nice heart warmer.

Saturday, July 26, 2008

Bags o' bats

More live action reporting from the BCI acoustic class! Today is the first full day of class. Last night we were out recording bats until 2am, so please excuse me if I'm not terribly coherent. Right now I'm taking a break from processing bat calls and waiting for dinner so I get a chance to post another update. Here's basically how this week-long class works. Breakfast is at 8:30am, which sounds great until you do the math on not getting to bed until 2:30am. Lectures start at 9am, when we gather in the great room here at the Winema Lodge next to Tule Lake and learn about different aspects of acoustic monitoring of bats. Today we went over the various species found in the Pacific Northwest and the call characteristics used to tell the different between species. For some of them it seems pretty impossible to tell them apart even when the experts are describing it. After lunch it's more of the same until dinner. Evenings are spent out in the field with the bats. There are three types of attendees. In addition to us students, there are a half-dozen instructors including the creators of the tools we are using in the field. There are also a team of "wranglers", experienced bat workers in the region who are here to catch the bats that we will practice our recording skills on. The wranglers head out just after dinner to set up nets at various locations and catch bats. They identify the bats and put them in small cloth bags which they store inside their jackets to keep warm. Periodically they transport them to a wide open space where the students and instructors are waiting. Then we release them in various ways and capture their calls with our recording equipment. We use those recordings to build up libraries of calls of known bat species. Those reference libraries are necessary to identify calls of unknown bats. Last night there were nets in different locations, and at least one of them was wildly successful. I think we had almost 100 bats to release! Sometimes there were so many that they put a half-dozen or so of a single type into one bag. At first we went slowly, spending time looking at and photographing the bats before releasing them. At the end there were so many bats we just let them go all at once. On the detectors it was like the finale in a fireworks show. The bat pictured here is an adorable Townsend's big-eared bat (Corynorhinus townsendii). Could those ears possibly be any bigger?

Friday, July 25, 2008

Live from Lava Beds

Setting up equipment Originally uploaded by
This week I'm up at Lava Beds National Monument, near the California/Oregon border, for the BCI Acoustic Monitoring class. I'm so excited to see my bat friends, the lovely scenery, and get all my questions answered. Since we have internet access here, I'm hoping to post photos and some of the highlights as the week goes by, at least until I'm too sleep deprived to function. In this shot you can see some of my classmates and instructors getting the equipment ready to record calls at an evening fly-out from a nearby lava tube cave. We later recorded calls from about a dozen different species. I got my detector and recorder set up to do handheld recording. To do this, I listen to the bat calls using headphones, and when I hear a bat go by (sounds like a series of clicks) then I push a button to save the data for later analysis on my computer.