Back to Panama, for the fifth fieldwork season of data collection of my PhD. I have three determined goals for this session : (i) collecting survival data, (ii) collecting DNA samples and (iii) manipulating group size. This is the third consecutive season where I am catching a network of a dozen roosts where I can determine group size.
During captures, animals are marked individually with transponders. With relevant statistical analyses, I will try and estimate survival based on recapture rates and detection probabilities. My species foraging in groups, group size probably has an effect on individual survival, that’s what we are trying to determine with these analyses. In parallel, I am collecting wing biopsies. These DNA samples will be genotyped to obtain microsatellites. They will be used to study relatedness of individuals within groups. I am especially interested in male reproductive success in function to group size. I assume it will be more difficult for the dominant male to insure paternity in groups with more females. And the main goal of this mission is to study the foraging efficiency (weight gain relative to time spent out of roost) in function to group size. Several roosts studied are equipped with automated systems with automated transponder reader and integrated scale. To investigate the effect of group size, I am comparing foraging efficiency for a group of normal size and of modified size. To modify group size, I capture individuals of the group that I keep for several days in captivity. Captive individuals are fed each night with mealworms and released within few days. I have already manipulated three groups, a fourth is ongoing and a fifth will come in the days to come. I have now collected a lot of data, in parallel I am now working on the analyses.
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I stayed a short month in Panama this summer – from mid-July to mid-August. The priority was to catch all the colonies we work on – more than 20 nights of catching for a total of around 300 bats. Many new bats have been transpondered and I have collected a lot of DNA (relatedness analysis) and feces samples (virus and diet studies). The highlight of the stay was the catch of 96 bats in one night. The catch started at 6PM and we finished processing the bats around 6AM.I had a small army of people from the batlab to help me – thanks to Teague, Basti, Julia, Sebas, Michelle, Toni, Santi, Dallas…
Unfortunately, three of the roosts with automated monitoring systems were abandoned (probably due to house renovation) but we installed two other automated monitoring systems. I also had the opportunity to present my PhD project to the scientific community – good practice with a lot of interesting questions. In addition, I helped Sebas for a parallel project. As a pilot study for his master thesis, we equipped these bats with heart-rate and temperature transmitters. The bats were kept in captivity and video-taped. This preliminary data will help understanding the relationship between heart-rate, temperate and clustering prevalence. My fieldwork season is over but Sebas will stay until early September to operate more trials and continue this project in November-December, when we both go back for a new fieldwork season. We have been tracking two species of bats in the last weeks.
For Teague's project on information transfer, we tracked Uroderma bilobatum, a small leaf-nosed bat eating figs. During 10 days, we tracked a handle of bats from 7PM to 5AM to learn more about their foraging grounds and see if the bats were foraging together. Two of our bats seemed to forage at the same fig tree but we need additional studies to prove it. In parallel, we tracked a roost of 11 Molossus molossus - the model species of my PhD. The idea of this tracking session was to assess the prevalence of group hunting in this species. Unfortunately, all the collars with the transmitters were removed after 2 days. We moved on to additional tests of collars in captivity but we could not design a collar that would stay long enough on bats. The tracking session of Molossus molossus is cancelled, we are now focussing on data collection at roosts and also analysing data. It's been already more than a week I am settled in Gamboa for my third fieldwork season of my PhD.
I am accompanied with Matthieu Ménage, a french bat guy, to help me in the field. We had a busy program in the past days with several nights of catching and transpondering individuals of Molossus molossus in different colonies. We have also installed two more automated systems to monitor automatically bat activity with Pit-tags (individual use of roost, emergence and return times, weight gain). The more recent program was focused on collar testing. Usually, we glue radio-transmitters on the back of animals. However, this procedure is not ideal as Molossus molossus can remove the transmitters with their feet and also scratch off their fur. We are now developing, with tips from Teague, hand-made collars to glue the transmitters on. We have realised tests on captive individuals, kept in baby tents for a few days and hand-fed by meal-worms. The design of the collars is promising but requires further tests. I'm going back next week for a third fieldwork season in the village of Gamboa Panama. Program: to continue data collection on my doctoral model species: Molossus molossus. And a field mission requires a bit of organisation !
As with all trips, I organize for me and my assistant the housing and transportation (plane, train, taxi ...). Together with my french assistant, we will live in an apartment provided by the host institution, the Smithsonian Tropical Research Institute. These homes are located in the village, near my roosts of bats. To complete my research legally, research permits for sample collection (skin, guano) must be written in Spanish and sent to the Panamanian authorities before verification. When my fieldwork season comes to an end, I will send a report of my fieldwork season and ask for an export permit to bring back to Germany the samples collected. And to complete the organization for the field, preparation of material is essential. Checking nets, preparing telemetry equipment, electronic testing, preparation of materials for sample collection ... the list is long! And before I go, I am working on my fieldwork program to plan the 11 weeks in the field. Catch sampling, radio-tracking ... More news when I'm on the ground! For my Phd fieldwork in Panama, I use a wide variety of tools to measure, to transponder and to sample the bats I catch, often with help from fieldwork assistants or some colleagues. I use generally 7 tools, described here and shown on the photo below. 1. The first tool is a scale, used to measure the weight of the bat (placed in a soft clothed bag). This feature gives a good idea about the age of the bat or if it has eaten. For examplen, my species weighs around 10g and can come back from foraging weighing 3-4g more. 2. The second tool is a calliper, used to measure the forearm length. This feature is often used as an help for species determination. 3. The third and fourth tools are a transponder needle mounted on a transponder injector. The needle contains the transponder that will be quickly injected under the bat skin of the bat. This is a sensitive operation but I trained and I process quickly. The transponder - with an individual identification number - will be injected once and will last for the whole life of the bat. Once the transponder is inserted, I check the number with a hand transponder-reader. 4. To sample DNA, I use a biopsy wingpunch. This tool consists of a 3mm-diameter metal ring mounted on a plastic pole. The DNA is sampled on the wing membrane, the "wingpunch" is then stored in a small tube of ethanol. The sampling on the wing membrane is optimal because this body part contains a lot of DNA and the healing really quick (around 2 weeks). Another story starts after for exportation of the samples, extraction of the DNA and of course the analyses... Thanks to Hyuen-Ji Lee for the picture :).
PS: All catching and sampling procedures are realised with permissions from the Panamean authorities. A little article on PIT tags was published in June's STRI newsletter. My boss and I use this technology
to recognize marked bats using a hand-transponder reader and also to recognize bats when they crawl through the automated balances that I have installed in Gamboa. "How does one track the comings and goings of bats, birds, frogs and other animals? A rice-grain sized PIT tag injected under the skin makes it possible to identify individuals using a hand-held tag reader. Passive Integrated Transponder tags consist of a small glass capsule containing electromagnetic coils that act as a combined receiver/transmitter. When triggered by an interrogating signal, the antenna in the tag uses voltage generated by the signal to radiate an alternating magnetic field coded with a unique ID number. This technology was first developed in the 1940’s to distinguish friendly from enemy aircraft. The same concept lets you open a door by waving a card in front of a reader. Since the 1980’s PIT tags have been employed to monitor fish populations and to identify valuable zoo animals and pets. Radio Frequency Identification Technology in printed tags tracks goods in the global supply chain. Seven millimeter-long PIT tags cost a little less than $5.00 each." During last weeks, I focused on fieldwork and writing.
I have finally 5 automated balances installed and connected to direct power but I still have to solve technical problems and start analysing the data to see if the balance is acquiring the data required for the project. I still have one month to make sure balances are correctly working before coming back to Germany. In parallel, I have also invested a lot of effort to write the first chapter of my PhD. This wednesday I received a lot of feedback from the people of Rachel Page's lab. I still have a lot of work to do but I have now a clearer view about where I am going. As an extra, I will present next monday a small talk for kids of the school of Gamboa called "The secret life of bats" to do some public outreach about bats. Yann Over a month has passed since the last blogpost. The schedule was busy, with an emphasis on installing my automatic scales. The crucial part is for the bats to accept the change of entrance of theirs roosts. For that I gradually modify the roost entrances with pieces of wood and I check acceptance by bats using video recordings. The first balance is expected to enter service this week!
Among other activities, I presented my project to the scientific community of Gamboa and I plan to make a public outreach presentation on bats to children of the village school. I also spent writing the first chapter of my PhD and also on export permits. After acceptance by the future government of Panama, this permit will allow me to export my DNA samples from bats and later proceed to the analysis in Germany. I postponed my departure from Panama two weeks to be able to install all scales. Back in Germany scheduled for mid-July! Meanwhile, more pictures and news on this blog :). |
AuthorLittle blog about my bat research and conservation action Archives
October 2023
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