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.


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!


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


Adorable face of the little yellow-shouldered bat.


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.


Check out that face.


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).


Just half of the gigantic wingspan of this bat.


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**

Thesis, Graduation and Bat Science

A late post, but there is a lot of catch up on.

Everything I had worked towards for the past three years came to an end in May. I successfully defended my thesis project on social calls in Yuma myotis. This involved a public 45 minute presentation to my thesis committee, friends, fellow graduate students and other Humboldt State University students. Following the presentation, and several edits of my thesis manuscript, I had collected the signatures and a completed copy of my thesis was sent to the department office! Even though the graduation ceremony wasn’t until a few weeks after all of this, I had officially completed my master’s degree! The next steps will be more editing and maybe some extended analysis and hopefully a publication.


After being hooded during the ceremony. 

With my father, Bill Brokaw.

With my father, Bill Brokaw.

This fall I will be continuing my academic and bat research journey at Texas A&M University (where I will be starting a PhD program in Biology. More on this later). First, I was offered an amazing opportunity to conduct bat surveys in the Mexican jungle as a volunteer bat scientist. The past 6 weeks I spent my nights chasing bats through Calakmul Biosphere Reserve with Operation Wallacea. Operation Wallacea (also known as OpWall) is a British organization conducting conservation research through academic partnerships. Overall, the organization runs expeditions around the world, conducting biological surveys in jungles, savannahs, coral reefs and deserts. University students from around the world act as research assistants and conduct their own dissertation research. OpWall also hosts groups of high school students, providing a hands-on experience for potential future field biologists and conservationists. All of the science staff are volunteer scientists, professionals and former research assistants.

Each field site conducts general biological surveys, ranging depending on the specific location. Calakmul Biosphere Reserve is located at the base of the Yucatan Peninsula. It is one of the largest protected areas in Mexico and is part of the Selva Maya, the Mayan rainforest that extends into Guatemala and Belize. It is home to all of the major wild cat species of Central America (including jaguars, pumas and ocelots), numerous migratory and endemic bird species and of course, huge diversity of bats. It is also home to one of the largest Maya cities ever uncovered in the Maya lowlands, Calakmul.

It was an amazing experience. Writing just that sounds very glib, but there is no other way to describe the last six weeks. I experience just a glimpse of neotropical bat diversity, met and worked with amazing people who are as passionate and crazy about field work, bats and wildlife as I am, exchanged crazy ideas and theories about why these bats do what they do and enjoyed last late night laughs, endured mosquitoes, stink bugs and stinging bees. In short, I didn’t want come home!

There is so much to share, it is going to take multiple blog posts to share everything. But here are some photos as a teaser of what’s to come.

The ruins at Calakmul


Great fruit-eating bat


Operation Wallacea and other signage at KM 20, the main research camp.  

Wedgetail sabrewing

Wedgetail sabrewing


Field work is a fickle friend. Sometimes you hit the jackpot (lots of bats, you hear the telemetry signals from every animal, you find the tracks you need, the weather is perfect etc) and sometimes you are just cold and wet with no data to show for it.

After a great night a few days ago, I was feeling optimistic about our capture chances last night. It had rained a little bit on Monday, so we hoped the bats would be out the next night, making up for lost foraging time. Instead, it was windy and chilly and not a single bat in sight. I am tempted to blame it on the fact I wasn’t wearing my lucky bat shirt (we field scientists entertain silly superstitions as much as the next person). Whatever the reasons, we didn’t catch any bats last night.

The point here is, there are no guarantees in field work. Nights with no data can be frustrating, but we have to work to keep things in perspective. To me at least, a few hours sitting next a creek with wet feet is still better than hours and hours in a warm office cubicle. It is the little things.

And while we didn’t see bats last night, we still caught a glimpse of some other local wildlife. Even our nets didn’t go unused, when a confused little dipper found its way into our nets just as sunset. American dippers are common around the redwood streams. They are unique little birds that spend their time dipping in the water and are the only truly aquatic songbirds in North America. They have a distinctive white third eyelid that allows them to dive in search of prey.

American Dipper we caught in our nets just at sunset.

American Dipper we caught in our nets just at sunset.

Some other visitors included a large millipede, a raccoon moving along the water’s edge and a brave little mouse that was intent on stealing our tortilla chips.



Also check out the short video I took of our brave little mouse-friend: LINK 

Bats are Back (alright)!

“Everybody, yeah, Flap those wings, yeah, Everybody, yeah, Flap those wings, yeah, Myotis bats are back, alright!” (sung to the tune of “Everybody” by Backstreet Boys).

Although spring officially began a few weeks ago, it seems the local Myotis species have just noticed the change. At the very least, they have definitely swung into town in full foraging force. Last night was the first night of our spring migration netting efforts as we try to track down the silver haired and hoary bats as they move through the redwoods to their summer ground (wherever those happen to be). This means April and May will be filled with lots of netting nights as we ramp up our efforts and try to maximize our chances of data collection and potential recapture data.

We opened our nets right at sunset and almost instantly began catching bats, sometimes two or three in a net at a time. Even more bats could be seen flying around, particularly along the edge of the water, expertly maneuvering their way around, over and past our nets.

Setting up triple high nets over the Albee Creek, Humboldt Redwoods State Park.

Setting up triple high nets over the Albee Creek, Humboldt Redwoods State Park.

We caught the usual suspects (California myotis, Yuma myotis, silver haired bats and hoary bats). However, we were pleasantly surprised with the capture of two species we have not seen in the area since last summer.

We caught three fringed myotis (Myotis thysanodes), two of which were females. We have caught this species at this particular site in the past, but not since about July or August. Fringed myotis are distinguished from other small brown bat species in the area by their slightly longer eared and the distinctive hairy “fringe” along the edge of their uropatagium (skin between their legs and tail). Other bats, such as long-legged myotis (Myotis volans) will sometimes have a little bit of a fringe, but not nearly as thick as the fringed myotis.


Fringed myotis before take off.

Bringing back the 70's with a thick fringe (fringed myotis uropatagium).

Bringing back the 70’s with a thick fringe (fringed myotis uropatagium).

I was pleasantly surprised by the first bat that was taken out of the net, a long-eared myotis (Myotis evotis). This was my first time encountering this species in the redwood forest, though we caught several of them last summer at Lassen National Park. As you might guess, long-eared myotis have long ears (more than 20mm in length)!

Long eared myotis (Myotis evotis).

Long eared myotis (Myotis evotis).

Once we have a bat in hand, we make several important observation and measurements.  Some measurements, such as ear length and presence of a keel (flap of skin at the bat’s ankle) help us identify species. We also measure forearm length using calipers. This gives a general sense of a bat’s size and can also help with species identification in some instances. We record the sex of a bat and also the reproductive status. In males, reproductive status is determined by looking for the obvious presence of testes (which will bulge around the penis) and the fill level of the epididymis (the tubes that deliver sperm from the testes to the penis). This observations provide information about the reproductive readiness of an individual. If the bat is actively producing sperm and in mating condition, we expect the epididymis to be full and the testes to be easily visible. In females, we look at the condition of the nipples, which can tell us if a bat has recently nursed young. During the summer, lactating females are easily identified by the tiny bit of milk that is present. Females that have never reproduced will have very small, almost undetectable nipples. Age of a bat (adult or juvenile) is determined by looking at the joints of the bat fingers (wings). In juveniles, there is a visible gap or “window” in the joints where the bone has not finished growing together. In adults, these joints are more rounded and knobby, lacking that “window”. Finally, we take a weight measurement, which can give us insight into the bat’s condition. If a bat is nice and heavy, then chances are he/she has been successful foraging. Bats are generally heavier in the summer, after they have had time to replenish fat stores used during winter migration or hibernation.

Looking for nipples.

Looking for nipples.

Using a light to look at the  finger joints to determine age.

Using a light to look at the finger joints to determine age.

I made this short video to show you more of how we take measurements on the bats: Processing a Live Bat.

All of this data helps us gain a better understanding of the diversity and abundance of bat species in an area and insight into how they might be using the habitat (such as a migration corridor or summer maternity roosting). It is going to be a busy spring and I can’t wait to see what we catch next time!

A mo-hawked silver haired bat, waiting to take flight.

A mo-hawked silver haired bat, waiting to take flight.

“Bat” to Basics

Happy Bat-urday!

Spring seems to have come early to Humboldt, unlike much of the rest of the country where March is certainly coming in like a lion. Unfortunately, the past few weeks I’ve been cooped up in my office while the sun shined, wrestling with R code, manipulating graphs, eating lunch and dinner at my desk, typing away at the finishing steps of my master’s thesis.

I first decided I wanted to be a research biologist when I was 10, after finding the definition of “zoologist” in an encyclopedia. I knew I wanted to work with animals and this mysterious job seemed to fit me perfectly. As I grew older, I continued to explore wildlife biology and field research. As I searched for colleges, I was presented with images of students abroad, hiking mountains, playing with lions or smiling with eagles. As it turns out, there is way more to wildlife biology and research in general than you think about when you are 10 years old.

It reminds me of this meme that I’ve seen bounce around Facebook and other social networking sites in the past:

Wildlife biology

The last picture “What I actually do” has felt pretty realistic the past month or so. Field work is my bread and butter, it’s what makes me happy. Spending time connecting with the environment and getting to know the habits and behaviors of a study animal. Yet, it seems like for every hour of field data, is at least an hour in front of a computer, building code, running statistical tests, writing reports or theses. I don’t mean to sound petty, or like I am complaining. This is where wildlife biologists can make a real difference, disseminating their research among the public, sharing and exchanging information with colleagues, exploring new ideas and pursuing scholarship.

But, like I said, being out in the field is the biggest thrill of all. Last night, I got the chance to get my feet wet again (literally….we were walking in the creek all night) and remind myself why I chose this profession.

We headed back down to Humboldt Redwoods, where we had intensively netted last fall for migratory bats. Katelyn Southall, a wildlife student at Humboldt State is collecting data for her senior thesis on social calls in silver haired bats. The rains from earlier in February meant the creeks had been full and things had settled down enough for us to safely traverse in the water and setup nets.


Bull Creek, Humboldt Redwoods State Park

The week of warm weather seemed to have been a boon for the bats, and was a boon for us. It was a migratory bat filled night, with multiple silver-haired bat captures, two hoary bats (the first of 2015!) and the uncommon western red bat.


Silver haired bat

Hoary bat, calmly in hand

Hoary bat, calmly in hand

Poorly lit photo of a western red bat (only so much you can do with a phone camera)

Poorly lit photo of a western red bat (only so much you can do with a phone camera)

And my pinnacle achievement for the night: using my fancy new smart phone to get a slow motion video of a hoary bat taking off into the night. The video can be viewed here.

Bats of Northwest California

I have realized that in my posts I refer to a variety of different bat species. While the number of species found in this area is not particularly large, it can still be confusing. I thought it would be fun to give some brief descriptions of the common bats in this area (plus show off some of my better bat photographs).  All information on bat descriptions was obtained from Mammals of North America by Fiona A. Reid (which is a great resource if you are interested in mammal identification and ecology).

California Myotis (Myotis californicus)


This is one of the smallest species found in this area. They are generally reddish brown in color, with dark brown ears and wing membranes. In addition, they are identified in this area by their relatively small feet and the presence of a keel on the calcar (a small flap of skin on the ankle of the bat).

Yuma Myotis (Myotis yumanensis) / Little Brown Myotis (Myotis lucifugus)


Caught in action, emerging from the roost for nightly foraging.

In the redwoods, these two species are almost morphologically identical, small, brown bats without a keel on the calcar. Yuma myotis tend to have whiter fur on the belly, though it is difficult to use color as an identifying feature. Little Brown Myotis are slightly larger than Yuma Myotis. Both are commonly found around water and are often found inhabiting human dwellings. On the east coast, Little Brown Myotis are facing large population losses due to white-nose syndrome, though western populations have not yet been affected by the fungus. Information on white-nose syndrome can be found here:

Silver Haired Bats (Lasionycteris noctivagans)


The distinct silver haired bats of one of the tree bats found in this area. Instead of roosting in large colonies in houses or in caves, these bats rely on tree snags and crevices for roosting and migrate each season. They have a thick black fur tipped with silver, and fur extending down the uropatagium (skin flap between the legs of bats).

Big Brown Bats (Eptesicus fuscus)


One of my favorite bats, Big Brown bats are fairly large and brown, with long, dog-like muzzles. On the east coast, this species has also been affected by white nose syndrome, though not as drastically as the Little Brown Myotis. They are common in manmade structures in the east, and roost primarily in trees and cavities in the west. In addition, they will become awake in response to temperature change, and can be spotted out and about even in mid-winter.

Western Red Bat (Lasiurus blossevillii)


Another gorgeous tree bat, the western red bat is about the same size as a silver haired bat, with thick red and white fur. The uropatagium is also extensively furred, and can be pulled up over their body like a blanket. These bats remind me of little lions, with a bush of red hair on their head and beautiful red and black patterning on their wings. They most likely roost in deciduous trees, particularly along riparian areas such as streams.

Hoary Bat (Lasiurus cinereus)


The most striking and kingly of North American bats, and the largest at almost 30g. They have distinct silver tipped fur and a yellowish-white ruff around their neck. Like the silver haired bat and red bat, they have a furred uropatagium which helps keep them warm in colder temperatures. These bats are migratory, and are facing threats from wind energy.

The next few bats I don’t have good example pictures of, but are occasionally captured in the redwood forests.

Fringed Bat (Myotis thysanodes)

A myotis bat with ears that extend past the tip of the nose if laid forward. Most distinctly is the fringe of hairs along the edge of the tail membrane, hence the name.

Long-legged Myotis (Myotis volans)

Another long earred myotis, they have long forearms and reddish brown to blondish fur. The underside of the wings closest to the body are slightly furred (i.e. furry armpits) and they have a keeled calcar. We don’t commonly catch this species, though this past summer we caught a lactating female, indicating some reproductive individuals in the area.

Hope that helps clear up some questions about the bat species in the area. This is not a comprehensive coverage of bats of California, just the species we most commonly catch in our nets. If you are looking for more information on bat species in California and throughout North America, check out Bat Conservation International’s species profiles, which can be found here: Species Profiles

Bats in a Tent

In addition to my acoustic playbacks and monitoring through the northwest (California and Oregon), I also collected some data through bat captures. After going through the permit application process, multiple emails back and forth between California Department of Fish and Wildlife biologists and more emails, I was finally permitted to handle bats for my project starting in late July.

One of the major drawbacks of my current protocol is the inability to determine individual responses to bat social calls. While I can estimate general activity before, during and after social call playbacks, I am unable to determine more specific details about an individual bat, such as species, sex or age. By adding a capture component to my research, I hope to be able to draw more detailed conclusions about how bats respond to social calls.

Testing bat responses to social calls require a more controlled environment, where the bat won’t simply just fly off. I needed something easily assembled in the field, easily transported and not too expensive. Turns out tents used for tail-gating and outdoor meals are the perfect solution: easy assembly, with mesh panels available to keep insects out (in my case, keep bats in). The more research I do, the more I realize how everyday objects can be hacked or adapted for wildlife research!


Peeking inside the flight tent.

Bats were captured from local foraging areas, such as Benbow Lake State Recreation Area, Headwaters Forest Reserve and forest land owned by Green Diamond Resource Company. Initial capture attempts were focused on Green Diamond land, but with low capture rates I investigated other locations. The large number of bats at Benbow Lake State Recreation Area and the lack of water due to California drought meant easy pickings when it came to bat captures. One net over a puddle of water caught over 20 bats in about 20 minutes!

Following capture, bats were processed using usual methods, measuring forearm and weight, and determining sex and age. Both adults and juveniles were used in flight trials, and I hope to be able to compare their responses to social calls. A small bat box was mounted on either end of the flight tent, with cameras recording at both ends, supplemented by an infrared spotlight. The bat was placed on a table and confined by a small plastic bin over the top, and the tent was closed up. Using a pulley system, the bat was released at the same time as a call was being played. Sounds broadcast were either Myotis echolocation calls, Myotis social calls or Tadarida (free tailed bat) echolocation calls. Some bats were released without any call being played, to act as a control for how bats might behave in the flight tent. After letting the bat fly or crawl at free will in the tent for 5 minutes, the side of the tent was removed and the bat was allowed to fly out on its own. That process worked for the most part, though twice I had a second bat fly into the tent from the outside environment (which happened to only occur during social calls…promising!).

Determining age of a Myotis. An individual is designated as either adult or juvenile based on the growth of the epiphyseal joint in the finger bone. If you can see a small window when back-lit, then the joint has not grown in completely, indicating a juvenile.

Determining age of a Myotis. An individual is designated as either adult or juvenile based on the growth of the epiphyseal joint in the finger bone. If you can see a small window when back-lit, then the joint has not grown in completely, indicating a juvenile.

Setting up the equipment and getting the cameras ready to record. You can see the small plastic box used to contain the bat prior to broadcast, connected by a rope to the top of the tent.

That’s me setting up the equipment (and looking super stylish in my waders), getting the cameras ready to record. You can see the small plastic box used to contain the bat prior to broadcast, connected by a rope to the top of the tent.

Armed with more infrared video data, I hope to be able to determine how bats are responded to these social calls. This will be done by measuring the amount of time the bat spent flying on different ends of the tent, as well as measuring behaviors such as circling, approaching or landing. Knowing demographic data such as sex or age makes it possible for me to compare behaviors between individuals and determine if all bats respond the same way to these calls.

Still lots to do and lots more video to watch, but I hope to have some updates soon!

Bat Research Benefits Species and Students

I know it has been a long time since I last posted a blog entry. I have lots to share about the past few months. My time has been split between my research efforts and data processing, helping a fellow graduate student and a local bat biologist with their field work. I will post photos and updates about those projects soon, but I wanted to share a story about bat research at Humboldt State from the Humboldt State now blog.

A few weeks ago, we were accompanied into the field by a professional photographer and videographer. It was a relatively slow night in terms of bat captures, but we were able to demonstrate most of our techniques and show off some of the beautiful local bats species. They did a great job and were just as enthusiastic about the wildlife as the rest of us!

There’s also a video highlighting the beauty of working in the redwoods, as well as some great shots of the bats. Hope you enjoy and I’ll be back soon with more details about recent activities.

Link is here –> Bat Research Benefits Species and Students

Bat Fat Crew

For the past two weeks, I’ve taken a break from my field playback experiments. One reason for the scheduled break is to work on wedding planning and begin some data analysis from my first three weeks.

The data collection didn’t stop, and for my lab-mate Jeff Clerc, it was just beginning. Jeff just finished his first year of graduate school with my advisor, after receiving his bachelor’s degree in wildlife at Humboldt State. I volunteered to help Jeff train assistants for bat capture, and to help with bat handling, since the assistants are just finishing their rabies inoculations. We spent three days at Humboldt Redwoods and three day in Lassen National Forest catching bats, trying to specifically target silver haired bats.

For his thesis, he is interested in the population dynamics and migratory patterns of bat, specifically tree roosting bats such as silver haired bats. While found almost year round on the north coast of California, silver haired bats are generally migratory, roosting in warm inland locations during the summer and the more mild, coastal habitats in the winter. Despite our fairly intensive efforts capturing bats this past fall and winter, we rarely encounter both sex, instead catching mostly males. This leads to the question, where are the females?

Additionally, while it is generally accepted that these species migrate south and to the coasts each fall, the exact geographic locations where these bats spend summers or winters is uncertain. Researchers studying migratory birds have had strong success using feather isotope analysis to study movement patterns. Different environments have different levels of chemical isotopes, such as nitrogen and phosphorous, which can be tracked through the food web and various organisms.  By analyzing the ratios of certain isotopes in a feather, scientists can determine where that particular feather was grown. There has been limited success using isotope analysis on bats using fur. While promising, this type of research on bats has two major downfalls: the exact molting and growth patterns of bats are not as well understood or regular as bird molts and even if they did, the isotopes to do provide fine scale analysis of habitat or location, but more broad geographic regions.

As aerial insectivores, bats are food limited. During the summer, they forage extensively, putting on fat stores to get them through long migrations or periods of hibernation. This extensive foraging during a relatively short period of time means that the fat composition stored during this time should bear the chemical signatures of the ingested food. Bats foraging in different locations will be feeding on slightly different insect communities, which should be reflected in their energy stores. By analyzing these fat stores, researchers should be able to determine what geographic regions these bats migrated through. The use of this fatty acid signature analysis (FASA) has been successful in some pelagic bird and marine mammals. Jeff’s thesis will test if these differences can be detected using fat removed from a bat, and if different regions result in different chemical compositions, using silver haired bats as a model.

We started out netting at Humboldt Redwoods, an area we are familiar with. Surprisingly, it turns out that the coastal redwoods of California may be the only place in the world where we catch more bats in the fall and early winter than we do in the summer. Luckily, we still managed to catch a few of the target species, to collect their fat. The procedure is done with institutional and state approval, and causes minimal distress to the bats, not even drawing blood.

Jeff processing a bat.

Jeff processing a bat.

Holding a silver haired bat.

Holding a myotis bat.

Taking fat from the bat!

Taking fat from the bat!

Batting on Lassen National Forest land was a very different story. We weren’t really sure what to expect when we headed out to the park, about 5 hours east and up from Humboldt county. It was much warmer and drier than Humboldt, and our mist netting stream spots were few and far between. This was promising, since more limited water sources meant that it would be much harder for bats to avoid our nets. It turned out bats were really not good at avoiding the nets, as we caught about 30 bats in under an hour. Under more normal circumstances, this wouldn’t be as crazy, but since only Jeff and I were vaccinated and experienced enough to take bats out of nets, it was a very busy hour. By the end of the first night we had caught close to twenty silver haired bats (male and females, as well as a few juveniles and lactating females), and several Myotis (including a new species for me, Myotis evotis (long legged myotis). Our second night we were a little more prepared, but still caught about 20 bats before shutting down the nets.

Collection of bats waiting for processing.

Collection of bats waiting for processing.

Myotis evotis (long legged myotis.). Look at those ears!

Myotis evotis (long legged myotis.). Look at those ears!

Silver haired bat, still feisty post processing.

Silver haired bat, still feisty post processing.

Releasing a bat, caught in action.

Releasing a bat, caught in action.

After showers at the ranger station and a trip into Susanville for more ice, we moved west about 30 miles to a slightly different field site (still in Lassen National Forest). The area was much lusher and greener than the first two nights, and we staked nets out at a pond/meadow area. After a thundering lightning storm narrowly passed by us, the temperature dropped and the insects seemed to clear out of the area. While there were still a few bats flying around, we shut down the nets after catching a few small Myotis. Then we made the long drive back to Humboldt, where Jeff will process his fat samples before heading back to Humboldt Redwoods this week.

Decontaminating nets during the day.

Decontaminating nets during the day.

The boys testing out water depths at the site on the third night.

The boys testing out water depths at the site on the third night.


Notes from the Field #3

For my third week of data collection, I pointed my infrared cameras at some local bats. My third field site is at a Humboldt County park, called Swimmer’s Delight. My box was mounted alongside the Van Duzen River, which winds its way through the park and alongside Route 36. The park is located within a large redwood grove, where several large hollow redwoods serve as great roosting locations for multiple bat species. In addition, a small colony of Myotis roost under the shingles of the park ranger’s trailer, located just on the premise. The weather was perfect, getting very warm during the day and cooling down at night.

My little bat box.

My little bat box.

On the 4th of July, my friend and fellow graduate student Cari and my fiancé Brad joined me for some sunshine and barbeque. We spent the holiday lounging in the sun and playing fetch with the two Labrador retrievers that Cari is pet sitting. On Saturday Brad and I made a trip down to Humboldt Redwoods State Park, the same place I spent the fall and winter catching bats. This time, we were there to take advantage of the well-maintained trails for long runs. Following the run, we visited the Women’s Confederation Grove Redwood Grove for a picnic lunch. This particular grove is home to an albino redwood tree, hidden just off the driveway. Instead of the regular green needles, the albino tree has white needles. The lack of green pigment (and chlorophyll) means that the tree is unable to photosynthesize and generate its own nutrient source. As a result, it has highly stunted growth and lives as a parasite on a regular redwood. This particular albino is one of just ten albino redwood trees in California.

Fire hearth at the Women's Confederation Grove

Fire hearth at the Women’s Confederation Grove

A nice quote from the hearth at the grove.

A nice quote from the hearth at the grove.

On my last day in the field, I spent some time exploring Grizzly Creek Redwoods State Park, which consists of a few virgin redwood groves along Route 36. These particular redwood groves were used for filming by George Lucas for his Star Wars sequel Return of the Jedi. Overall, it was a laid back week of data collection. After the end of this data collection week, I took some time off from my field playback experiment to focus on data collection from bat captures. Just as I was finishing up my week of data collection, my application for a scientific collecting permit to mist net bats was approved. In addition, my lab mate Jeff Clerc started his data collection mid July and I volunteered to help him train his undergraduate helpers.