Viewing Landscapes the Way Bats Might View them: Little Brown Bat Roost Use in Colorado

Unfortunately, North American bat populations have been struggling to overcome the impacts of a new disease (white-nose syndrome; www.whitenosesyndrome.org), moralities at wind energy facilities (http://www.batsandwind.org/), and declines in insect prey (http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185809). These challenges have bat biologists and conservation biologists scrambling to figure out how best to maintain populations of these nocturnal wonders. Yet, strategizing for these threats requires an understanding of the natural history and population ecology of these poorly-understood species.

Zoologists Rob Schorr and Jeremy Siemers of the Colorado Natural Heritage Program are trying to fill in the blanks regarding population dynamics of one of the bats most affected by white-nose syndrome, the little brown bat (Myotis lucifigus). For 3 years, Schorr and Siemers have been conducting mark-recapture studies of little brown bat maternity colonies in northwestern Colorado, and, in 2017, recruited two ambitious Colorado State University undergraduate researchers to understand what other roosts little brown bats use. These talented undergraduates (Kira Paik and Toryn Walton) tracked little brown bats that were fitted with small radio-transmitters. They discovered that the bats tended to return each night to roosts that are within a couple miles of the main maternity colony.

In addition to following them around, the researchers decided to get a peek at what these bats see from these newly-discovered alternate roosts. They employed a DJI Phantom 3 drone to take video from above each roost to look at the surrounding landscape. Although difficult to quantify, the video (this one from the main maternity colony) reveals what might be interpreted as a “neighborhood” with most roosts within sight of each of each other (within <2 miles). It is unclear why little brown bats return to roosts within close proximity, but it may have something to do with access to cohorts, available prey, and water resources.

See the CNHP drone in action the video below!

Understanding the Complexity of Little Brown Bat Summer Populations

North American bats have been experiencing unprecedented declines because of a novel disease called white-nose syndrome, wind energy conflicts, and likely because of declines in their insect prey. White-nose syndrome is a disease caused by a cold-loving fungus, and when hibernating bats are infected the fungus shows itself as a white fuzz on the muzzle, ears, and face of bats. When the disease hit eastern bat populations the evidence was clear, as hundreds of dead bats were found at the openings of caves that used to be home to thousands and millions of bats. In western North America, understanding when such a disease hits will be more challenging because many winter roosts house much fewer bats. For example, in Colorado, the largest winter colony of bats is approximately 600.

Because of a lack of large winter colonies, Colorado Natural Heritage Program zoologists Rob Schorr and Jeremy Siemers are turning their attention to monitoring summer colonies. Since 2014, Schorr and Siemers have been conducting mark-recapture studies of little brown bat (Myotis lucifugus) maternity colonies in northwestern Colorado. They have inserted passive integrated transponder (PIT) tags in >1,000 bats, and rigged their roosts with PIT-tag reading antennas to record the arrivals and departures over the summer. These data are valuable for estimating survival of bats and understanding fidelity to roosts.

This year Schorr and Siemers recruited two ambitious Colorado State University undergraduate researchers, Kira Paik and Toryn Walton, to understand what other roosts little brown bats use. Paik and Walton spent the summer tracking 22 little brown bats that were fitted with small radio-transmitters. They discovered that the adult female bats, despite traveling over 30 miles on their evening feeding travels, tended to return each night to roosts that are within a couple miles of the main maternity colony. This knowledge is extremely valuable for understanding where additional mark-recapture effort should be directed if biologists want to identify bat population trends.

Little brown bats after being tagged.

Siemers & Schorr marking little brown bats. 

Little brown bats flying around one of the maternity roosts.

Paik & Walton with the field vehicle for tracking telemetered bats.

Paik at the harp trap with a captured bat.

Walton tracking one of the telemetered bats.

Chiroptophilia - A Post-CNHP Adventure

By Savanna Smith
(former CNHP work study)

As a Chicago Botanic Garden Conservation and Land Management botany intern at the Shoshone Field Office of the BLM, my love for plants has grown exponentially this summer. I’ve gotten to know the best method for beating the seeds off a Purshia tridentata bush, smelled many a sagebrush, and puzzled over whether or not a Penstemon’s anthers dehisced from the center or the sides. However, I can’t deny my roots in the field of wildlife biology, which is what I studied as an undergraduate. As a climber, it seemed natural to be interested in bats since they often roost in the cracks and crevices only accessible to rock climbers. (For any other wildlife-enthusiast climbers out there, you should check out Climbers for Bat Conservation on Facebook, a cool citizen science project!) My undergraduate thesis research dealt with the acoustic side of bat science, but I didn’t participate in any of the field work for the data. So, you can imagine my excitement when I learned that I would get to assist in several bat-related projects this summer.

The first project involved setting up stationary acoustic bat detectors with Ross from Idaho Fish & Game - this work was conducted for the North American Bat Monitoring Program, a continent-wide protocol aimed at gathering data on the status and trends of bat populations across North America. After securing these detectors during the daylight, we waited until nightfall to conduct mobile acoustic surveys. This involves attaching a bat detector on top of the truck and driving at a constant speed for at least 25 km, all while recording the bats flying overhead. This was fun because I got to watch the calls coming in on a spectrogram in real time.

Last week, myself and other interns had the opportunity to attend a bat bioblitz - an event where scientists attempt to capture all the biodiversity in an area. We set up triple-high mist nets over the river and patiently waited for bats to fly in. We saw and recorded many bats, but only managed to trap two in the nets. Regardless, it was really cool seeing them up-close and learning how to take measurements. At our station, we captured an adult female silver-haired bat (Lasionycteris noctivagans) and a juvenile male Yuma myotis (Myotis yumanensis).

We camped out after the bioblitz and got a quick night of sleep before returning to the office for a day of caving in Gypsum lava tube, the second largest lava tube in the continental US! This was a new experience for me, and I enjoyed the pressing silence and impenetrable darkness that each bend in the passage concealed. In the tube, we found pack rats, a jackrabbit carcass, and even a few bat friends hanging out almost two miles into the tube! It was a great experience to put myself in such a different environment.

I’m thankful that this internship has allowed me to gain experience in a variety of areas, especially since bats are creatures I’ve been interested in for a long time. I only have six more weeks left here in Idaho, and I’m excited to see what’s next.

Sunset view before the mobile acoustic transect.

Adult female silver-haired bat. 

Juvenile male Yuma myotis. 

The entrance to Gypsum lava tube.

Jackrabbit carcass.

Kind of low quality photo of the inside of the tube - check out the multiple levels!

Kira and Toryn's Bat Blog

What are Kira and Toryn doing?
We’re following bats! Rob and Jeremy placed radio transmitters on the backs of nine female and one male little brown bats. We are using radio telemeters to track the signal emitted by the radio transmitter to the bats’ locations. When we find the bats, we collect data on their roosting site, including what type of structure they’re roosting in (such as a building or a tree), temperature, roost opening height, total structure height, slope, aspect, elevation, UTM, and other descriptors depending upon the structure type.

Little brown bats in a bat box at Rehder Ranch. 

Roosting little brown bat.

What does a normal day look like?

Since we’re studying bats, many people think we collect our data at night. However, the majority of our data is collected during the day, with a few observations at night. During the day, we find the bats and collect data on their roost sites. Finding some of the bats is easy; others . . . not so much. The transmitter signals can bounce in weird ways in a valley, forest, or building wall. Some signals can't be heard until you are right on top of them; other times you can hear the signal from every direction and have a hard time pinpointing its location. So it occasionally boils down to good luck when finding some of these bats.

One method for tracking bats is using a car-mounted antenna for radio telemetry.

Kira and Toryn locating bats with radio telemetry.

What do we do at night? 

The field work we do at night consists of mist netting, bat counts, and going around to roosting sites to check if the bats have left their day roost site. On June 21st, Rob accompanied us to Sarvis Creek to mist net for bats. A mist net was placed near an unused cabin, and night vision cameras and infrared lights were set up and aimed at the suspected exit roost site to get video of bats. We completed our setup around 8:00 p.m. and didn’t start seeing bats around 9:00 p.m. Kira kept seeing bats that Rob and Toryn didn’t see. Kira may have excellent eyesight or is a liar. Rob and Toryn were going crazy trying to spot the bats Kira ‘saw.’ Unfortunately, we didn’t catch any. However, we saw a ton of them swooping down the river catching bugs.

We also got permission from a private landowner to do a bat count on his property on 06/27. We set up night vision cameras and infrared lights at his doorstep at 9:00 p.m. where there was a pile of guano. We visually counted bats until 11:30 p.m. Kira is probably better at spotting bats than Toryn. The bats can be hard to count because they are difficult to see and you don’t know if you’re counting the same bat. This is why a night vision camera is set up because we will later review the video recording to see the amount of error of visually counting bats versus video recording of the bats. It was fun doing a bat count at night. We lounged in chairs watching the sunset and the stars come out, chit chatting and drinking tea. We also heard mountain lions in the distance, which was cool until Kira decided to tell stories of mountain lion attacks. Thanks Kira. 

The other type of night work we do is visiting the day roost sites. Currently the bats seem to return to the same day roost site every day. This has us worried because we aren’t sure if the radio telemeters fell off the bats or if the females have pups. So we visit the day roost sites at night to see if the bats are moving. Sometimes the bats are moving and aren’t at their sites, and sometimes they are still there.

Setting up for mist netting at Sarvis Creek Cabin. 

Nighttime setup for a roost count. 

What do we do in our free time? 

Nap! We nap a lot. Kira’s favorite napping spot is in the hammock. We also swim and fish in the stream (Kira’s better at fishing), explore the downtown, read books, and watch The Hobbit when we are trying to stay awake until 3 a.m. to check on the bats. We plan on inner tubing down the Yampa River and going hiking.

Kira's rainbow trout.

Toryn's first monstrous catch of the day!

The Bethke Elementary “Bat-Bots” and Creative Solutions to Deter Bats from Wind Turbines

The Bethke Elementary Legos Robotics Team, called the Bat-Bots, invited Rob Schorr to talk with them about bat conservation and ecology. The Bat-Bots are tasked with coming up with solutions to reduce bat mortality at wind turbines. In 2012, it was estimated that over 600,000 bats died at wind turbine facilities in the United States (M.A. Hayes. 2013. Bats killed in large numbers at United States wind energy facilities. BioScience 63:975-979). They were all aware of the importance of bats for insect control and pollination, and were concerned about conflicts between renewal energy from wind energy development and bat conservation. They wanted to know about possible solutions to reducing bat deaths, while maintaining access to clean energy. Schorr and the team discussed options to use ultraviolet (UV) light as a deterrent (P.M. Gorresen and others. 2015. Dim ultraviolet light as a means of deterring activity by the Hawaiian hoary bat Lasiurus cinereus semotus. Endangered Species Research 28:249-257). The team discussed how to design buildings with UV lights, and were contemplating ways of designing new turbine facilities with dim UV light deterrents.

The Bethke Elementary Bat-Bots include Case L., Carly L., Juliana S., Ella N., Abigail F., and William W., with Schorr.  

Discussing Bat Conservation and Jumping Mouse Habitat Restoration at Western State Colorado University

In November, Rob Schorr visited with the student chapter of The Wildlife Society at Western State Colorado University to talk about bat conservation. After driving to Gunnison, he met Dr. Pat Magee and his students and spent several hours talking about CNHP and some of the bat conservation projects CNHP is involved in. Of particular interest was student involvement in recruiting climbers to take part in the Climbers for Bat Conservation project. This project is a partnership between bat biologists and climbers to discover new roosting colonies of bats in rock crevices. While at WSCU, Rob also spoke with Dr. Thomas Grant’s master’s-level restoration ecology course about the challenges of doing habitat restoration for bats, and about the habitat restoration work he is conducting for Preble’s meadow jumping mice with Colorado Parks and Wildlife and Douglas County Open Space.

Western State Colorado University on a chilly November afternoon.

46th Annual Symposium of the North American Society for Bat Research

In October, Rob Schorr attended the 46th Annual Symposium of the North American Society for Bat Research in San Antonio, Texas. During his time there, Rob presented a poster discussing the progress and data analysis from a project to monitor maternity colonies of little brown bats (Myotis lucifugus). He and Jeremy Siemers have been conducting a mark-recapture study of little brown bats at two roosts in the Yampa Valley. The intent of this project is to develop baseline estimates of survival, understand roost fidelity, and describe roost conditions for the little brown bat.

Rob manning his poster at the 46th NASBR meeting.

The Mission San Antonio de Valero (The Alamo) was right across from the meeting venue.

Photographing Wing Venetation Patterns of Little Brown Bats

By Blaise Newman, CNHP Siegele Intern

Little brown bats (Myotis lucifugus) are widespread across North America. They vary in color from reddish, brown, to golden with a wingspan of 8 to 11 inches and an average weight of less than half an ounce. In the summer, female little brown bats aggregate at sites called maternity roosts which can be found in buildings, caves, and other covered areas.

Unfortunately, the little brown bat is under attack across its range. White nose syndrome (WNS) is a fungus that disturbs the bat’s hibernation pattern wasting valuable energy needed to survive the winter. In eastern North America, the disease has killed millions of bats. The disease has yet to be detected in Colorado, but a recent detection in Washington state has scientists concerned. The Colorado Natural Heritage Program and Colorado Parks and Wildlife have started an ambitious project to monitor little brown bat maternity colonies in the Yampa Valley of Colorado. Obtaining baseline of data of bat survival and persistence prior to WNS is extremely valuable.

At two maternity sites, Jeremy Siemers and Rob Schorr are using passive integrated transponder (PIT) tags to monitor the adult female and juvenile bats. PIT tags are similar to radio-frequency identification (RFID) chips in your pets. PIT tags are unique identifiers that can help estimate mortality, understand behavior, and track population changes over time. However, one major concern for this marking technique is tag loss. For this reason, new methods of individual identification are being explored to work in conjunction with the PIT tags.

Wing venation is a promising identification tool. Similar to a fingerprint, wing venation is thought to be unique to each individual bat. After the bats were captured and tagged, I spread the wings of captured bats over a light board to show the distinct venation patterns. I then used a mounted camera to document the bat wing venation to be analyzed and cataloged later. Hopefully, future studies will be able to identify individual bats using both PIT tag and wing venation IDs.

Blaise Newman, CNHP Siegele Intern, photographs a little brown bat's wing venation pattern. This technique is fairly new, and holds promise as a way to identify individual bats.

Beer, Brats, and Bats: CNHP Partners with the Yampa Valley Land Trust and the Wildlife Society

In August, the Central Mountains and Plains section of the Wildlife Society (CMPS) hosted its annual meeting in Steamboat Springs. The Colorado Natural Heritage Program and The Yampa Valley Land Trust welcomed attendees of the CMPS Society Annual Conference for a relaxing evening of food, beer, and bat conversations. Guests got to see the bat conservation work that is being done at the Rehder Ranch. Here is a link to an article on the fieldtrip produced by The Yampa Valley Land Trust. CMPS is a section of the international association of wildlife biologists called The Wildlife Society. It includes wildlife biologists from Colorado and many of the surrounding states.

Jeremy Siemers (left) and Rob Schorr (right) sampling bats at the Rehder Ranch outside of Steamboat Springs, Colorado.

Using Rock Climber Observations to Find Bat Roosts

On a hot summer day above the South St. Vrain River, zoologists Rob Schorr and Andrew Reed stare up at a 50 foot slab of rock that has been carved by glaciers and rivers and time.They arrived at this particular location by the goodwill of Colorado’s rock climbing community.As part of a project that Schorr, botanist Bernadette Kuhn, and human dimensions specialist Shawn Davis developed several years ago called Climbers for Bat Conservation, Schorr and Reed are visiting this specific location because climbers have reported hearing or seeing bats in the cracks above. Reed, a rock climber,led the effort to look in the cracks and flakes for bats, guano, or insect parts, while Schorr watched enviously from below. After three hours of searching manually and with an ultrasonic acoustic detector they were unable to find any bats along the climb, and they were unable to find any guano on the rock walls or below the cracks. Schorr found a few insect parts below the climb, but it was unclear if they were the remnants of feeding bats. Although they did not stumble upon a large roost of bats, they were glad to follow leads provided by the Climbers for Bat Conservation partners. The CBC group is hoping to receive more observations of bats by rock climbers following a recent presentation to the International Rock Climbing Research Association given by Kuhn in Telluride, Colorado.

Andrew Reed looking in cracks for bats along the climbing route Panic in the Grey Room.

Andrew Reed pointing out the cracks, flakes, and crevices where bats could roost.