Hi Folks
Well as I mentioned yesterday, we took last night off from trapping bats. This morning I took Diah and Mimi into the forest to start mapping the trails that are off the grid. I’ll explain that in detail another time.

Today I thought I’d tell you a little bit more about what Julie has been up to. If you remember, she has been taking pictures of the bats with their wings stretched out so that she can describe the shape of each species’ wings in detail. We want to know if there are differences between species and if that affects where and how they can fly.

To test their performance when flying, she (with quite a bit of help!) has been building a huge flight cage. The idea is that the bats will fly through an obstacle course inside the flight cage and we can score how well they do. We can then see how the scores relate to the shape of the wings. But first we had to build the cage…….

Everyone was needed to get the sides into position

Once the sides were up they could be nailed into place

The hardest part was getting the roof on!

The finished product -- now all that is needed are the banks of strings that will act as obstacles

The obstacle course is made up of six sets of strings (we call each set a “bank”). The distance between the banks can be changed to make it easier or harder for the bats, and the distances between the strings within in a bank can also changed (again to make it easier or harder). Julie will test each species at inter-string distances (distances between the strings) of 10, 20, 40 and 60 cm, matched with the same inter-bank distances. See the diagram below to get an idea.

A diagram of the obstacle course design, seen from above

We plan to video the bats when they are flying to see how well they do. Each string is connected to the base with a magnet. If a bat hits a string, the string will come loose and we will be able to score that as a “touch”. In theory, a bat that is very manoeuvrable will not “touch” any of the strings, even when they are very close together (say 10 cm inter-string distance). That kind of bat should be able to forage in the really dense parts of the forest understory, and we will see what kind of wing shapes match up with being able to forage in “clutter”.

Other bat species may not be so good, and will touch lots of strings or perhaps even refuse to go through the obstacles at all. Those bats probably fly in the more open parts of the forest and should have different wing shapes from the bats that do well with the obstacles.

So that’s the theory!! We have done a few test flights, but tonight she hopes to start collecting actual data!

Setting up the banks of strings that the bats have to fly through. It can be a hot job when the sun is on the flight cage, hence the big hats. I don't think its a very exciting job either, because the girls have been singing at the top of their voices all afternoon!

Julie and Zam getting the banks of strings ready for tonight