Ross Baker gave a talk on the amazing wildlife we encountered on our Earthwatch trip to the Pantanal in September-October 2008, illustrated by a range of slides. It came as no surprise to the audience, I am sure, that the majority of these were of bats! This was in fact the main focus of the expedition, which we took part in as volunteers helping out on one of the many research projects sponsored by the Earthwatch Institute.
The project is based in the heart of the Pantanal in a remote pousada (Brazilian farm-based tourist accommodation), and was designed primarily to investigate the effects of deforestation caused by cattle grazing on a range of fauna including reptiles, amphibians and otters, as well as bats. Led by researchers from the University of Matto Grosso do Sul, we headed out each evening to a different field site, selected to represent forest areas subject to low-, medium- or high-level impact from grazing, the most obvious effect being increasing levels of understorey removal. There we set up mist nets and trapped bats from dusk (around 6pm) to midnight. Each bat caught was identified to species, weighed, sexed, and any ectoparasites associated with it were removed and stored in ethanol for later identification. Fruit-eating species were also kept in a cloth bag for around 30 minutes: any faeces produced were collected and stored for later identification of any seeds, to build up a picture of the plant species eaten by the bats, which perform an important role in pollination and seed dispersal, and thus regeneration of forest species.
Bats were also tagged so that later recaptures could be identified, using a lightweight collar for the larger species and a band (similar to those used for bird ringing, except that the band goes on the bat's forearm) for smaller bats. As the bats were released into the forest afterwards, Ross made recordings of their ultrasonic calls using a bat detector attached to a digital sound recorder, which we later analysed using special software at home - although isolating the calls of a single bat from the cacophony of ultrasound in the sky around us was challenging to say the least!
We caught a total of 13 species, the majority of which feed mainly on fruit, pollen and nectar, with the remainder being carnivorous or insectivorous. But the most exciting of these for us was the common vampire - one of three species of vampire, all of which occur in the area, though sadly we did not manage to catch either of the rarer species. And yes, they do feed on blood, although not by sucking it through puncture wounds as the movies would have us believe, but by making a shallow incision with their razor-like incisors (see photo), adding an anticoagulant and lapping the blood - mainly from cattle rather than humans.
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| Common vampire | Tropical screech owl caught in one of the mist nets. |
It was a wonderful experience - not least the comfort and hospitality of the pousada in which we stayed, complete with swimming pool, great food, and a lakeside location teeming with other wildlife including birds, cayman and even a giant anteater.
Not all Earthwatch accommodation is so luxurious, but we would nevertheless recommend the experience to anyone who loves wildlife and wants to make a contribution to saving our threatened species and habitats.
Lynn Whitfield