Hi Folks
If you remember, Ain’s project is all about trying to work out when the bats breed. Our hypothesis is that most females will time things so that they are lactating (producing milk), which is very costly for them in terms of energy, when there are most insects about. So to find out when most insects are about, you guessed it, we have to catch insects as well as bats!

Whenever we trap for bats we run two light traps. There are lots of different kinds of traps for insects, light traps exploit the fact that many insects are attracted to light (which is why they are always buzzing around the lights in the house here, and probably around any outside lights you have at home in the summer). The bulbs we use give out a blue-purple light which is particularly attractive to insects.

The light comes on at dusk (it has an automatic switch) and goes off in the morning. So after we have collected the bats, Ain has to stop by the two light traps we are running and collect the insects. That’s the easy part! The really hard work is then to sort out all the insects in the different orders. We can’t get the identifications to species, because there is too little known about insects here, and it would take years. Instead we identify to order (like dragonflies — Order Odonata, grasshoppers and crickets — Order Orthoptera).

Even sorting to order takes hours so its a good job Ain has some help from the USM students at the moment. Once all the insects have been sorted, the number of individuals caught in each order is recorded. They are then they dried in a toaster oven, before we weigh each order o give what’s called the dry biomass of the Order (the total dry weight of all the insects in that order). So for each night, we have two measures of the abundance of insects — the actual numbers in each order and the dry biomass of each order. These measures of abundance change through the year, and we are trying to match that up with the local weather and the bat breeding.

The next thing we want to know is whether the bats are eating the insects that are available in high numbers. Guess how you work out what a bat eats? Yep you have to look at the feces (poos!). You could look at stomach contents but then you’d have to kill the bat, so we are stuck with picking through poos. So whenever a bat is released back into the forest, we keep the bag it spent the night in, which most of the time will also contain fecal pellets. These also have to be dried in the toaster oven (the smell is AWFUL) before they are stored in small plastic tubes — one tube per bat. When Ain gets back to the US she will have a fun time trying to identify bits of chewed up insects that have passed through the bats.

It has to be said, that collecting insects and poos aren’t quite as much fun as just catching bats, but its all part of the research!

The light trap for catching insects. The white bar is the bulb, at night it glows a blue-purple color with which attracts the insects. They hit the metal panels which are set at right angles to one another and fall into the collecting bucket at the bottom

The light trap is powered by a car battery (top) which has to be recharged every day. Bottom: Ain at one of the traps, the tarpaulin keeps the worst of the rain out of the trap

Top: After sorting, the insects are dried in a toaster oven (yum!) before being weighed. Middle and bottom: sorting the insects into the major orders

The orders of insects that are caught in the light traps. Most of them are found around the world, and should be familiar from their common descriptions (in blue)