Calakmul Expedition: The Scientific Lowdown

To be honest, the last six weeks has been such a blur of amazing bats, wildlife, new friend and colleagues and jungle life, that I’m not really sure where to start. So, like most stories, the best place to start is just at the beginning.

I arrived in Cancun, Mexico on June 12th, the day before my contract was to start. I had been invited by Operation Wallacea to join the Mexico Jungle Expedition as a volunteer Bat Scientist. Based out of the U.K., Operation Wallacea is an impressive organization dedicated to both wildlife and biodiversity conservation and scientific education. They operate field sites around the world where both experienced and young professionals like myself can volunteer to gain experience, graduate and university dissertation students can conduct original research and collect field data and university research assistants and high school groups can cut their teeth on field work and what it is like to be a wildlife or field biologist.

Arriving in Cancun, I met a mix of my fellow staff members joining the Calakmul expedition, including several other bat scientist staff members, hailing from around the globe. Early the next morning we all piled into a mini bus to be taken to KM 20, one of the four camps at the jungle site and the first of the four to be opened for the 2015 field season. It was a long drive as we headed from the coast down to the base of the Yucatan Peninsula and into the Reserva de la Biosfera Calakmul (Calakmul Biosphere Reserve).

Dinner in Cancun the night before we head into the jungle.

Dinner in Cancun the night before we head into the jungle.

Upon arrival, we were greeted by Caroline and Kathy, the expedition coordinator and lead scientist for the Mexico expedition. We were given a tour of the camp facilities and some introductory lectures on health and safety, the biodiversity monitoring project and our basic responsibilities as staff members for the field season. While the rest of the staff settled in for their first night at camp, myself and other bat team members were too excited and decided to dive right into a short session of bat mist netting. We placed the nets near camp for a few hours, giving ourselves a little introduction to some of the more common bat species.

My home for the next 6 weeks.

My home for the next 6 weeks.

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Mist nets set up in the interpretive garden near KM20

One of the main goals for this project is to investigate the abundance, diversity and geographical distribution of a range of taxa in Calakmul, focusing on birds, bats, herpetofauna (reptiles and amphibians), large mammals and trees. Baseline surveys like this one can allow for analysis of relationships between variables like forest disturbance or habitat type and abundance of specific bird or bat species (among many other things). Starting this year, data collected will also be used to assess impacts of roads in Calakmul. The ruins at Calakmul (more on them later) are a tourist destination, though currently off the beaten path traveled by most visitors in Mexico. In order to increase tourism at the ruins, there is a potential for widening the roads and increasing the speed limit. As part of the surveys conducted by Operation Wallacea, additional camera traps and methodologies are being deployed to assess current road use by animals such as primates and large carnivores, and current effects of road disturbance on butterflies and herpetofauna.

In addition to collecting field data, the other objective for this project is education and field training for university and high school students. A few days after the staff arrived at KM 20, we were joined by a group of university research assistants and dissertation students, as well as a few more staff. During the first week, the university students were split into groups and would help staff on each of the different survey types. As a bat scientist staff member, together with the other bat staff I would be taking the students out at night for bat mist net surveys, where they would help record data, carry bats (safely secured in bags) and help with basic measurements. At the same time, we would teach the students about the measurements we were taking, how we determine species and other fun facts about bats. You get more than two bat biologists in a room and you won’t be able to shut us up. These kinds of interactions were great not just for the students, but for me as a bat biologist still early in her career.

Students helping us take measurements during a bat mist net survey.

Students helping us take measurements during a bat mist net survey.

Each night we surveyed a different transect, setting up 6, 6-meter mist nets along the transect. Nets were set perpendicular to the transects as much as possible, though sometimes we were constrained by the surrounding vegetation. Our goal was to capture the bats using the open rides and gaps in the forest as commuting paths, though we would also be capturing bats as they were foraging. Bats in the understory of the jungle as incredibly well adapted to flying in cluttered environments, which makes them adept at also avoiding our mist nets. The goal is to catch a bat off guard, so that it doesn’t detect the net until its too close to escape.

The Neotropics is home to the world’s great diversity of bat species. The exact numbers vary depending on who you ask, but recent numbers estimate as many almost 140 species in one country (Costa Rica), with Mexico clocking in with at least 100 bat species. By comparison, the United States is estimated to have between 45- 48 bat species (and the United Kingdom a paltry 17 species)! Much of this diversity stems from one bat family, the Phyllostomidae, with approximately 192 species and up to 56 genera. These bats are found throughout Central and South America, as well as the Caribbean and southwest United States. Also called New World leaf-nosed bats for the fleshy projections that extend above their noses. Bats in this family echolocate through their nose, and the nose-leaf is thought to help direct the echolocation calls. Members of this family have evolved to fill almost every food niche, including fruit, nectar, insects, pollen, frogs, other bats, birds, lizards and even blood.

In just our first week of capturing bats, we caught a total of 15 species, and nearly all of the bat species on our collective “bat wish lists”. All of the captured bats were species new to me. But even more exciting, we caught species that my fellow bat staff had never captured before, such as the amazing Centurio senex and Nyctinomops laticaudatus. Just proving the power of bat surveys in the tropics!

Some featured bat species from the week:

Jamaican fruit-eating bat (Artibeus jamaicensis) – One of the most common bat species caught in the understory of the rainforest. A large and stocky bat with velvety fur. Diet includes a range of fruits, flowers, pollen, leaves and insects. These bats use their large canines to pierce the tough outer skins of fruit like figs, which they carry back to a night roost to eat. Occasionally, we would capture a bat with a piece of fruit in the net next to it!

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Jamaican fruit-eating bat

Little yellow-shouldered bat (Sturnira lilium) – Another common species. A small stocky bat with no uropatagium and very hair legs. Usually has bright orange, deep yellow or dark red shoulder patches, which are also the source of a sweet musky odor. This odor is most pronounced in active adult males.

Smelling the little yellow-shouldered bat

Smelling the little yellow-shouldered bat

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Adorable face of the little yellow-shouldered bat.

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Example of the dark shoulder patches on this species.

Peter’s ghost-faced bat (Mormoops megalophylla) – A bat with what can only be described as a peculiar face, belonging to the family Mormoopidae (leaf chinned bats). Insectivorous and rarely caught in mist-nets. We only caught two over the course of the season, both in the same night!

A face only a mammalogist could love!

A face only a mammalogist could love!

Wrinkle faced bat (Centurio senex) – Though this bat technically belongs in the same family at the nose-leaf bats, it has no nose-leaf. The naked face is highly folded and wrinkled, folds which may be used to direct fruit juice into the mouth while feeding. This amazing bat also has bright white shoulder patches and a lattice pattern on the wing, composed of stripes of pigment and transparent skin. The folds on the chin can be pulled up over the face like a bat bandit mask.

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Check out that face.

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The lattice patterning on the wing of a C. senex.

Broad-eared bat (Nyctinomops laticaudatus) – One of the many free-tailed bat species found throughout the world. These bats are generally high flying and uncommonly caught in mist nets. We captured one in a net and upon returning to the processing station, noticed another bat flapping on the ground. The bat from the ground then flew to a tree and proved to be a second individual of this same species! An insectivore and commonly found roosting in Maya ruins.

A broad eared bat, angrily protesting processing.

A broad eared bat, angrily protesting processing.

Mexican funnel-eared bat (Natalus mexicana) – A small delicate bat, often orange in color. The legs and tail of this bat are long, more than half the length of the entire bat! Insectivorous and incredibly agile. We were lucky to catch even one of this bats. Hundreds of them could be seen streaming through the forest at dusk, next to the cliff on one of the transects.

Mexican funnel eared bat, displaying the full length of its legs and tail.

Mexican funnel eared bat, displaying the full length of its legs and tail. That long tail contributes to this species incredible maneuverability. 

Great false vampire bat (Vampyrum spectrum) – Largest bat in the New World, with a wingspan of almost a meter and comparable to some of the flying foxes found in the Old World. Also, carnivorous, feeding on birds weighing up to 150g and small mammals (including other bats species).

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Just half of the gigantic wingspan of this bat.

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Me and the largest bat in the Neotropics!

And this was all only the first week! More details to come soon!

**All natural history information about these bat was obtained from personal observation and from A Field Guide to the Mammals of Central America and Southeast Mexico, Written and Illustrated by Fiona A. Reid**

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