We Found a Western Red Bat in the Nature Gardens: A Small Visitor with Big Implications

October 31, 2014


Western red bat, Lasiurus blossevillii, photo by Ted Weller, US Forest Service.

Happy bat week everybody—we have bat-tastic news to share with you just in time for Halloween!  Over the month of September we recorded not just one, but TWO new species of bats that had never before been detected in the Museum’s Nature Gardens. Firstly we found the non-migratory and somewhat urban-adapted canyon bat, Parastrellus hesperus. This bat is common throughout the southwest and is strongly associated with rocky crevices found in canyons. Because they roost in these dark places and are able to remain in the same location year-round, this may mean they can adapt to roosting in urban spaces in L.A.—anything from cracks in concrete underpasses to crevices on hillsides that are too steep for development. However, even more exciting was the detection of a second species. In fact, I was so surprised to see this bat turn up that I had to get a second and third opinion. Behold the western red bat, Lasiurus blossevillii, which hasn’t been recorded near the Museum since 1941!

Western red bat in the Museum's Mammalogy collections.

Unlike the canyon bat and other urban bats, western red bats are especially sensitive to urbanization.  The California Department of Fish and Wildlife has included them in the state’s list of sensitive species, and many local bat experts considered this bat to be absent from the Los Angeles basin. However, back in 2007 some of my scientist colleagues, Dan Cooper and Stephanie Remington, detected red bats in Griffith Park, which finally proved that these bats can persist in the city.

I didn’t expect red bats to be found in the Nature Gardens. Although the detection in Griffith Park and a few more in other parts of the Santa Monica Mountains, gave me hope, I was still pessimistic about detecting red bats at the Museum. Our gardens are much smaller than the wild spaces in the Santa Monica Mountains, and we’re much deeper in the urban core.  Also, the bat detector I help to manage in Griffith Park hasn’t detected any red bats since it was installed in 2012.

Everything changed on September 1, 2014. After I downloaded the data from the bat detector in the gardens, I noticed an interesting recording that I thought matched the call of a western red bat.  I shared the call with bat echolocation monitoring experts, Ted Weller from the U.S. Forest Service and Joe Szewczak from Humboldt State University—they were surprised by the recording. They both leaned towards identifying it as a red bat but it wasn’t the best quality recording so they recommended that I waited until I had a second one to make a more informed identification. I anxiously waited a few days and then recovered the next two weeks of data. Bingo! On September 12, we got another recording and this one was able to be positively identified as a western red bat!  I sent my bat colleagues the call and they unanimously decided that the Nature Gardens had indeed visited by a red bat, possibly on two separate occasions.

Years ago, red bats used to migrate south from Canada and overwinter here in Southern California. However, much has changed over the last hundred years in the region, and urbanization and western red bats don’t mix so well. So, It will be interesting to see if the bat—or maybe it was two red bats—sticks  around the Nature Gardens and stays with us or the winter, or if it continues to head further south. The detection of this tree roosting specialist points towards the importance of conserving natural habitat in cities because places like the Nature Gardens at the Museum can provide valuable habitat that these species still need in urban areas. It is also an indication that our little and wild oasis (3 ½ acres) is meeting its goal as both an urban wildlife research site and valuable habitat for wildlife in our city.

Written by Miguel Ordeñana

 


(Posted by: Lila Higgins)

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We Found Bats Living at the La Brea Tar Pits!

October 9, 2014

If you’ve ever been to the La Brea Tar Pits you might have wondered if bats were around during the last Ice Age when saber-toothed cats (Smilodon fatalis), Columbian mammoths (Mammuthus columbi), and dire wolves (Canis dirus) roamed the land that is now our city. Well, we’re happy to tell you that the answer is yes, and we’ve recently discovered that bats are still flying over the tar pits on a regular basis!

Me hanging out with a pallid bat (Antrozous pallidus) during field work—one of only two species of bats recovered from the prehistoric Tar Pits.

But how do we know that bats are still living in the Miracle Mile? It’s all thanks to bat detectors. Bat detectors are devices myself and other scientists use to record the ultrasonic calls—remember echolocation from biology class—that bats use to communicate, hunt, and find their way around in the dark. I then use special computer programs that turn the calls into sonograms so I can visualize the call. Because each bat species’ call is distinct, I can then tell which bats have been flying near my detector.

Here are some sonograms of bats I detected at the L.A. Zoo: Pictured top is the canyon bat (Parastrellus hesperus), and below is the Western mastiff (Eumops perotis).

In early July, I set up a bat detector along the shore of the big lake at the Tar Pits. I knew the site seemed like great bat habitat because it has a body of water which helps to support insects (a.k.a. bat food), and there are lots of trees for bats to roost in. However, this still felt like a big gamble to me. There are no bat specimens from the Tar Pits or Hancock Park in the Museum’s Mammalogy collection, and this is really expensive gear.

But after communicating with our paleontologists that work at the Page Museum, I learned that bats did in fact use the area during the last Ice Age. Research conducted by Bill Akersten (former curator at the Page Museum) in the late 1970s found that unlike the hundreds of dire wolves that have been found at the Tar Pits, bat fossils were rarely recovered because they are fragile and small. Only two bat species have been confirmed at the Tar Pits, the pallid bat (Antrozous pallidus), and the hoary bat (Lasiurus cinereus).  Although the environment has gone through dramatic changes since then, I find it remarkable that these two species still live in our region. But how many bats call the Tar Pits home today?

Just two months after I installed our bat detector in July 2014, we have discovered four species of bats at the Tar Pits! The detector has recorded the following species big brown bat (Eptesicus fuscus), canyon bat (Parastrellus hesperus), Mexican free-tailed bat (Tadarida brasiliensis), and Yuma myotis (Myotis yumanensis). I don’t find it that surprising that we didn’t record the pallid, or hoary bat as these species are more sensitive to urbanization. However, I’m hopeful that the gardens we’ve been planting at both the Tar Pits, and the Nature Gardens at NHMLA will provide good habitat for more species of bats.

Case in point—in September 2013, the Museum’s Mammalogy Collections Manager, Jim Dines, and I set up a bat detector in the Museum’s Nature Gardens. Over the last year, we’ve recorded four species of bats in the gardens. If you want to hear that story, you’ll have to wait until later this month during National Bat Week! So turn your echolocation on and stay tuned, and in the mean-time take a moment to think about the bats that fly over the Tar Pits and your neighborhood nightly, and what life would have been like for bats, birds, and bees in the Ice Age!


(Posted by: Miguel Ordenana)

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We Have a Bat Detector, and Bats Too!

October 2, 2013

Guess what? We have bats in the Nature Gardens! And we have proof, thanks to two of our intrepid scientists, Jim Dines and Miguel Ordeñana.

Here's the proof, in sonogram format:

Keep reading to find out what bat these blue and green blobs belong to!

Here's what Jim and Miguel have to say about our bat detector:

"Colleagues: Last Friday we installed newly acquired bioacoustic monitoring equipment near the pond in the Nature Gardens in the hope of documenting nocturnal aerial visitors. Yes, we’re talking about bats! Beyond expectation, our equipment has already recorded two different species of bats foraging in the Nature Gardens: the Mexican Free-tailed Bat and a Myotis species. Detectors like the one we are using are a great way to passively monitor for bat activity. The device records the ultrasonic echolocations that bats make, allowing us to later convert them into sonograms (graphic representations of the sounds) that can be analyzed using special software. Since bat echolocations are species specific, we can identify the species of bat based on their sonogram. Attached is a sonogram from the Free-tailed Bat we recorded. More than 20 species of bats occur in the greater Los Angeles area, but most of them are thought to inhabit non-urban habitats like outlying deserts and mountains. The Free-tailed Bat and the Myotis Bat we just documented are new records for Exposition Park. They join just one other bat species previously documented here based upon prepared specimens in the Museum’s mammal collection: the Hoary Bat.

Jim Dines, Mammalogy, Collections Manager

Miguel Ordeñana, Lead Gallery Interpreter, Field Biology"

After making this awesome discovery, Miguel added the sonogram as an observation to our L.A. Nature Map!

Mexican Free-tailed Bat, Tadarida brasiliensis

 


(Posted by: Lila Higgins)


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