Baby Got Bat

Last night we went out to do something that I have heard much about, but never seen in action.  We went mist netting.  For those of you not familiar with the term, mist netting is a technique used by ornithologists and bat biologists to capture birds and bats for research.  These nets are held up by two poles, looking much like a volleyball net when all is said and done.  They have long, lengthwise pouches that aid in the capture of whatever might fly into the net.  In this case we were netting for bats.  The bat species richness in the tropics is incredible and is higher than any other vertebrate species.  My group was especially excited to meet with the bat researchers since our project is focused on bats.  We went out to watch the nets being set up by the bat researchers at 6:30 pm; bats generally come out around 6:45 pm in Gamboa.  The net set up turned out to be more difficult than I originally expected; it was prone to getting caught and tangled and we were instructed that it could not touch the ground because it tends to pick up every leaf it encounters on the forest floor.


In order to work with a mist net one must be trained and certified.  It is important to check the net often and remove the animals quickly and carefully so they are not harmed.  Going into the netting I was told not to get my hopes up because in temperate zones researchers will set up nets and wait for hours with nothing to show.  However, within the first 20 minutes we had bats!  Total about 5 or 6 bats were caught; two bats were pregnant and quickly released.  After the nets were set up we left the forest to wait, then we were taken back in smaller groups to check out the net.  Some of the bats were also brought out to our group in a small felt bag so that we could all view them.  The first bat I saw was a Jamaican fruit-eating bat (Artibeus jamaicensis), a species of leaf-nosed bat.  The name “leaf-nosed” comes from the protrusion on their nose which is thought to play a role in echolocation.  This bat was pregnant, and as soon as the bat was freed it opened its mouth preparing to bite whatever it could.  The second bat was from the genus Coleura and was much smaller than the first.  It was amazing to see the little hunters and foragers up close.  Mist netting is a big part of bat biology because until more recent technological advances it was the primary way of studying bats, and is still probably the most reliable.  However, there are some problems with netting.  It is possible that some bats are better at avoiding the net and that some bats do not fly as low as others which might skew any measures of abundance.


There were many different experiments going on in the bat research group.  One study was looking into the role of vision in foraging species of bats.  Other experiments were focused on bat memory, looking into how well a bat might remember where a food source is or what was poisonous and what was not.  Jerry, who was in charge of showing us around, was doing research on true vampire bats which eat blood of other mammals, usually larger mammals such as horses or cows.  Vampire bats are very interesting in the ecological community because they share meals with each other.  If one bat goes out and finds food and another does not the bat that did not find any food will generally be fed by one of its roast mates.  This does not technically make sense, because according to most animal behavior theories animals should be selfish in order to survive.  Altruism has been documented in primate species and favoring of kin in some other lesser species.  However, the mechanisms behind the evolution of altruism are still very much debated.  Jerry was looking at the importance of kinship vs. previous encounters/ongoing roast mate relationships in these sharing interactions and hearing him discuss his research was very intriguing.


Seeing the bats, and the mist netting, and hearing about some of the research being done was all fascinating, but my favorite moment of the night was when we were able to use the class echolocation detector, or echo meter, with Jerry.  The data my group is collecting is on bats as I mentioned previously.  We have been going out every night with a wildlife acoustics echo meter, in hopes of studying species diversity and abundance in the grassy fields outside of the tree line versus that within the rainforest.  None of us are bat experts so although the device was Iding many species, we were not entirely sure that it was IDing the bats correctly.  We were also a bit confused about how to interpret the visual readings.  Jerry was able to walk us through some of the different features of the echo meter as well as show us what a searching call looks like and what it looks like when the bat finds the insect he was hunting.  The longer lower sounds are the searching calls, while the sharp drops on the screen indicate that the bat has located its prey.  Overall it was a very exciting and informative night and we got some reassurance that our data collection is not for nothing.  I am so excited about all of the exotic plants and animals we are seeing on this trip and all that we are learning from the guides and experts accompanying us.  I hope to learn more about the bats in the tropics as we get further along in our data collection and research so that I might be able to share with others what I have been so fortunate to learn from this experience.

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