L.A. Bats Fight On!

October 5, 2015

Happy (American) football season everybody! Yes, some scientists enjoy playing and watching sports in addition to searching for wild animals and staring at tiny things under a microscope. This is true for me. Growing up in a Nicaraguan family, playing and watching sports was a big part of my life. Nicaraguans are known to be baseball fanatics, but my mother and I, both being USC alumni, are also serious Trojan football fans.  I’ve been watching the Trojans play at the L.A. Coliseum since I was a young boy and now I take my little brothers to games. But, even when a game is playing out below, I can't completely turn my scientist-self off–particularly when there are bats involved. Let me tell you about the bats that Fight On!

Mexican free-tailed bat (aka Brazilian free-tailed bat) from NHMLA's mammalogy collection. 

It was this season's home opener against Arkansas State. I attended the game with my mom, stepdad, cousin, and two little brothers. I stopped by my office before the game to pick up my bat echolocation (the ultrasonic calls that bats use to communicate, hunt, and find their way around in the dark) detector because I was going to scout out an area for a bat program the following day. I put the detector in my pocket (iPhone ultrasonic microphone attachment) and rushed over to meet my family. We enjoyed the blowout game like any other fans do–cheering, high-fiving strangers, and eating delicious junk food.  

Enjoying the USC football game with my brothers and cousin, just before I saw the bats!

It didn’t seem like the night could get any better until my 13 year old brother, Aaron, spotted something flying overhead and yelled, “Miguel bats!” I looked up, spotted one and exclaimed, “Good eye Aaron!” I stared for a while in awe and then I saw another, and then another. At first, I was content just watching the bats fly around, dipping and turning across the night sky. But then I remembered I had a bat detector in my pocket. Nerd alert!

Using the echometer to scan for bat echolocations.

I quickly fumbled for the detector, attached it to my iPhone, and began recording using the free Echometer app. Luckily, the detector was picking up their echolocations. Over the next 20 minutes I recorded over 100 sonograms (graphs representing sounds) many of which I hoped would help me identify the bats later. I couldn't wait to get back to a computer to figure out what species were enjoying the game just like my family and I were.  But what were they doing here?

As I was trying to capture the bats' echolocations, I noticed they were hunting! As they flew in and out of the arcs of light, I saw them pick off moth after moth. At this point I was standing at the edge of our section, reaching out so my phone's microphone had a better chance of recording the bat sounds. I was worried because I might have been blocking someone’s view of the game. But quickly I recalled we were on the way to a landslide victory, and then I heard a lot of other people talking about the bats. It seems the bats were putting on a show for other fans too, not just for my family.

The game ended on a high note with the Trojans beating the Red Wolves 55 to 6.  

When I got back in the office and analyzed the sonagrams, I found out the bats I had detected were Mexican free-tailed bats, (Tadarida brasiliensis). Fifty-two of the 105 recorded sounds, belonged to these bats. The species are known for their spectacular nightly emergence from beneath Austin’s Congress bridge as they leave to consume millions of insects (a lot of them being pestiforous moths) in a single evening.  They are also known for their ability to adapt to urban areas by roosting in human structures.  This species was detected in Exposition Park for the first time in 2013 by our bat detector in the NHM Nature Gardens.  It was very gratifying to find out what species were flying overhead but it made me hungry for more answers.

Millions of Mexican free-tailed bats emerging from the Congress bridge, which has now become a tourist attraction (photo by Austin Convention and Visitors Bureau).

Are the bats roosting in dark corners and crevices of the coliseum during the day?  Are there more than one species feeding at the coliseum?  Do migrant bats use the coliseum structures like the Vaux swifts of downtown L.A. do on a seasonal basis?  Who knows, but it is notable how one single eye-opening experience can inspire so much wonder in unexpected places.  These moments remind us how many urban wildlife events are hiding in plain sight and as a result remain scientific mysteries. Perhaps, this story not only reminds us that wildlife spectacles sometimes occur unnoticed at commonly visited gathering spots (stadiums, amusement parks) but that there are other amazing wildlife moments we can observe once we simply begin looking. 

 


(Posted by: Miguel Ordeñana)

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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 NHM 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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Blooming Agaves

February 11, 2012

More plant news from the North Campus. Recently some of our blue lotus agaves, Agave ceslii 'Nova', have begun to bloom. This is an impressive sight as these plants send forth long spikes, (between four and six feet long), that look a lot like giant asparagus stalks. This type of agave is monocarpic, meaning that it only flowers once, and this particular selection happens to flower at a relatively young age compared to other species. Incidentally, the genus is commonly called century plant because it can take decades for them to flower. The entire stand of this agave (approximately eight plants) is flowering at the same time, because they were all propagated from the same tissue culture, which is a common nursery practice for certain landscape plants. Although flowering signals the end of the plant's lifespan, we can expect to enjoy the flowers and fruits for the next several months!

Agaves reaching up to the floss silk treeThere are over 300 species of agave in the world, with 100 species native to North America. This large array of species includes well known agaves such as the tequila or blue agave, Agave tequilana, and the sisal or hemp agave, A. sisalana. Other species are also farmed to produce agave nectar, which is sweeter than sugar and honey. The blue lotus agaves we have planted are native to Mexico and are becoming more common in the nursery trade. As with all agaves, the flower stalks possess literally hundreds if not thousands of individual blossoms, which are visited by many kinds of pollinators. The flowers will be a pale yellow color and will hopefully attract the numerous Anna's and Allen's hummingbirds that are already resident in Exposition Park. Unlike other agave species, the ones planted on the North Campus will not attract mammalian nocturnal pollinators, aka bats, which is a shame since we will be very soon putting up a bat box (more on that to come later)!

Four stately stalks!Stop by the North Campus and check them out today! They are close to the Dueling Dinos on the North side of the Car Pak along Exposition Boulevard.


(Posted by: Lila Higgins)


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Happy Halloween: Bats!

October 31, 2011

To help celebrate Halloween here are some bats! The Big Brown Bat, Eptesicus fuscus, is the most common bat in our area. They are easily seen at dusk flying around parks and water sources as they search for their insect food. We're putting up a  bat box in the North Campus in hopes that some of these bats will move in.

The Hoary Bat, Lasiurus cinereus, is another species often found in L.A. This specimen was collected at the Museum on the cafe patio a few years ago.

Last but not least here's the ghost-like Pallid Bat, Antrozous pallidus. Even though this species of bat is rarely found in the urban core, it is found in the desert regions surrounding Los Angeles. Unlike the Big Brown Bats these bats capture their food on the ground! They locate their prey by finding a perch and listening for insect footsteps (note the massive ears). When the right vibrations are heard they swoop down catch the unsuspecting insect and return to the perch to devour it!

Thanks to Jim Dines, the Museum's Mammology Collections Manager, for allowing me to photograph these awesome creatures!


(Posted by: Lila Higgins)


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