December 7, 2015
“Miguel, I found a dead bobcat!” It was 8:30 in the morning when I received a call from my friend Jessie Jennewein. Jessie and I work together at the Natural History Museum and share a passion for urban carnivores, such as pumas and bobcats. So you can imagine that this news got our day off to a bad start.
Bobcat repeatedly spotted using the same backyard near Griffith Park for over a year. Photo Credit: Susan Swan
Although Jessie’s news was sad, it didn’t surprise me. I’ve lived on the edge of Griffith Park for many years and have studied bobcats and other carnivores from the park. In this line of work I’ve seen a lot. I’ve set up camera traps and used radio-tracking to learn where bobcats live in the park and neighborhoods near my house. I’ve kept a roadkill bobcat in my freezer for a UCLA Ph.D. student. Once, I helped try to recapture a bobcat that was sick with mange due to exposure from rat poison. I expected Jessie to tell me she found it near my apartment on a street just outside of Griffith Park. However, the bobcat was actually found closer to Elysian Park. Elysian Park (0.94 square miles) was considered too disconnected from known bobcat populations, and too small for a typical territorial bobcat, which requires 3 square miles of space if it is male and 1.5 if it is a female.
Camera trap video (motion triggered camera) captured of a bobcat marking its territory in a remote portion of Griffith Park. Video Credit: Griffith Park Connectivity Study
The unexpected location of the dead bobcat initially made me worried about the status of this urban-sensitive species and how to study an elusive species in an urban landscape filled with private property. However, the opportunities to study them with citizen science left me hopeful about their future.
It all happened as Jessie was on her way home from my P-22 (the famous Griffith Park puma) themed party the night before (yes, I love P-22 that much!). As Jessie was about to get on the 2 freeway near Elysian Park, she noticed a dead bobcat on the side of the road. The next day, the specimen was brought to our NHM Mammalogy Collections Manager Jim Dines, who also recognized the significance of the locality. Jim and I had recently been discussing how our camera traps in the Atwater section of the L.A. River hadn’t captured any images of bobcats. Our study site wasn’t too far from where Jessie made her discovery.
Jim Dines speaking to Jessie Jennewein about the significance of the location where Jessie discovered the deceased bobcat near Elysian Park.
Before one can truly understand the significance of a dead bobcat on the side of the Glendale Freeway, it is important to have a little background about local bobcat research and ecology. Unlike other urban carnivore species with more flexible diets and social structures (e.g., coyotes and raccoons), bobcats are solitary and have a strictly carnivorous diet. However, they are able to eat a wide variety of small prey.
Research by the National Park Service shows that local bobcats prefer to eat small natural prey such as rabbits (first choice), gophers, ground squirrels, and woodrats. Griffith Park camera traps have also captured bobcats consuming Eastern fox squirrels and mice. Many of these small prey species live in backyards, presenting new opportunities and new challenges to urban bobcats.
Bobcat carrying the remains of an Eastern fox squirrel in the Hollywood Hills. Bobcats are important predators that help regulate small mammal populations. Photo Credit: Griffith Park Connectivity Study
Like most urban mammals, bobcats avoid humans by being more nocturnal. Researchers in both the Santa Monica Mountains and Orange County have documented bobcats and other urban carnivores coming out much later in areas with more human activity. Their small stature and brown spotted coloration also allows them to hide in thick backyard vegetation during the evening and the day and usually out of sight from home owners. The National Park Service has even documented female bobcats using suburban backyards as den sites, perhaps to protect kittens from coyotes that are more abundant in park interiors. Their small-size and stealthy behavior allow them to stay out of sight and out of mind of the media who tend to portray local carnivores as dangers to humans and pets. The National Park Service has studied over 300 bobcats in the L.A. area and none have ever been documented killing pets.
Regardless of their stealth, urban bobcats are still vulnerable in areas with poor habitat connectivity. The bobcat Jessie found was likely attempting to cross a matrix of freeway lanes to reach the L.A. River or perhaps some backyard hunting grounds in the neighborhood across the street. Even if they can safely cross a highway or street, bobcats face many other dangers, such as rat poison exposure which makes them more vulnerable to contracting and dying from mange.
Biologists have learned a great deal about the ecology and urban dangers facing bobcats in the Santa Monica Mountains, Orange County, and Riverside including areas as urban as Irvine and the Hollywood Hills. However, their range and population health further into L.A.’s urban core has remained a mystery. Will occasional roadkill fatalities, like the bobcat Jessie found, remain our only proof of their persistence in more urban areas dominated by concrete and private property or will we use these unfortunate clues as a call to action?
After a local community activist shared Jessie’s story with a local newspaper, local residents began sharing bobcat sightings with the same newspaper and the NHM citizen science team. A bobcat was reported in the Los Feliz neighborhood and three reports came from the Silver Lake neighborhood, including an ear-tagged individual sighted a few months later in a small greenspace between Silver Lake and Elysian Park-very close to where Jesse found the dead bobcat a few months earlier. The ear-tag was very exciting because unique ear tag colors allow researchers to more easily identify individuals!
Bobcat B-253 in Franklin Hills backyard near Griffith Park. Researchers were able to identify the individual as B-253, originally tagged in Griffith Park, by using the unique numbers and color combinations of the ear tags. Photo Credit: Shirley Mims
Upon seeing the ear-tag, I contacted Laurel Serieys, former UCLA Ph.D. who studied Santa Monica mountains bobcats and is now a post doc studying urban caracals in Cape Town, South Africa. Unfortunately, we couldn’t read the ID number or tell the true color on the ear-tags, so Laurel was only able to confirm that it was a bobcat that she either tagged in Griffith Park near the L.A. Zoo or it was a bobcat that she or NPS tagged in the Santa Monica Mountains west of the 101 freeway. Either way, it had an amazing journey.
I was relieved to learn that the dead bobcat wasn’t the last bobcat of the Elysian Valley. Intrigued by the wide ranging behavior of these bobcats, I decided to place a camera trap in Elysian Park. It took a few months due to widespread human activity but eventually I captured camera trap footage of an untagged bobcat! The experience probably created more questions than answers about Elysian Park and Silver Lake bobcats, but the main lesson was clear! Neither I nor anyone else can practically search for bobcats in L.A.’s urban core without citizen science. There is too much private property to cover without the help of local residents.
First photographic evidence of a bobcat in Elysian Park. Video Credit: Miguel Ordeñana
Fortunately another local biologist by the name of Erin Boydston feels the same way. Erin is a Research Ecologist with the USGS who focuses most of her research on urban bobcats. Following an iNaturalist training led by myself and Richard Smart, Erin set up a citizen science project based on iNaturalist called “Backyard Bobcats” that requests participants to submit georeferenced photos of bobcats from their backyards. Unlike other backyard carnivores, bobcats have unique spot patterns that allow researchers to identify individual bobcats even without ear-tags. Therefore, it is possible to not only document their presence but also their population density. As citizen scientists from L.A.’s urban core, such as Silver Lake and Elysian Park residents, continue sharing bobcat data from their backyards, Erin’s search will continue to expand deeper into more urban neighborhoods.
One of many bobcat photographs shared with Miguel by fellow Griffith Park neighborhood residents. Photo Credit: Susan Swan
Once Erin’s project gathers steam, population patterns may become more apparent, such as which bobcat individuals from rural areas also use backyards. Perhaps the habitat value of previously overlooked urban parks, such as the Silver Lake reservoir or small fragments in more underserved areas like Elysian Park or Highland Park, will be identified. Additionally, crucial habitat connections and corridors like the L.A. River and Arroyo Seco may be increasing the habitat value of these small parks by linking them together, creating a single, larger, and more functional ecosystem. Are bobcats using urban areas due to a lack of resources and space in local open spaces or are these bobcats thriving in certain backyard habitat? The public can help scientists like Erin map the health (e.g., photos of mangy bobcats) and distribution of bobcats throughout rural and urban areas by submitting their photos to Backyard Bobcats and the L.A. Nature Map.
Jessie’s discovery, while sad, did lead to the gathering of more data and increased awareness of urban bobcats in Los Angeles. My hope is that more people will send their bobcat photos to Erin’s project. It is only through data collected and submitted by Citizen Scientists that we will understand the role these charismatic wild cats have in our shared ecosystem and help us ensure that they have a long future in the City of Angels.
How to participate: Send backyard bobcat photos with date, time, and location information to the Backyard Bobcats and L.A. Nature Map using one of three methods:
May 10, 2012
On the tails (mammal and bird tails that is) of last week's post, I thought I'd continue to focus your attention on our wonderful new pond. Sam Easterson has set up some of his trusty camera traps next to the waterfall to see who might be visiting the pond. Check out the following images to see what he has found so far.
Nighttime is busy at the pond!
Stray cat...sorry, there aren't any fish in the pond yet
and no you can't eat them when there are!
Opossum...no tin foil in the pond either.
Although these night time endeavors are interesting, I think the action during the light of day is even more so. Over the last few weeks, Sam's traps have captured over 50 images of birds hanging out by the pond.
American Crow, Corvus brachyrhynchos
That is one good bath!
Black-headed Grosbeak, Pheucticus melanocephalus,
stops by for a moment.
Western Gull, Larus occidentalis, going in for a drink.
Camera shy Swainson's Thrush, Catharus ustulatus.
Male Western Tanager, Piranga ludoviciana
For the grand finale, watch three bird species drinking from the pond at once! We've got a Mourning Dove, Zenaida macroura, on the far left, a Western Kingbird, Tyrannus verticalis, center frame, and a Warbling Vireo, Vireo gilvus, doing a fly-by.
Want to see more creatures caught on camera trap? No problem, check out lots more pictures and videos on our flickr pool.
April 13, 2012
Remember back in December, when I said I'd let you all know if we had baby Virginia opossums, Didelphis virginiana? Well it's spring, and right on cue they're here! Sam Easterson's camera traps have caught the babies (we think there are three) on video over the last week, and although many people don't find opossum babies cute, there are a few of us here at the Museum that do. Check them out and make your own assessment.
Out for ride on Mom's back!
Here are some interesting facts about opossum babies.
January 10, 2017
March 16, 2012
We have another new sighting for the North Campus. A California ground squirrel has been spotted using the opossum den located underneath one of our Museum sheds. So far it seems that both the opossums and the squirrels are sharing the space!
Sam Easterson's camera trap captures the first image!
This is what Jim Dines, our Mammalogy Collections Manager, has to say about them:
The California ground squirrel, as its name suggests, is common throughout California as well as the rest of the western U.S. Scientists know this rodent as Otospermophilus beecheyi (formerly known as Spermophilus beecheyi). They are diurnal (active during the daylight) and, like other ground squirrels, live in burrows that they excavate or take over from other animals. Our ground squirrel has apparently moved into a den built by an opossum.
Ground squirrels eat seeds, nuts, and a variety of other plant material, as well as insects and handouts left by humans. Since they also invade gardens and cultivated areas, California ground squirrels are commonly regarded as pests. Their extensive burrow systems can be very destructive. They are also a host to fleas that can carry plague, so pose a health risk to humans and their pets. Rattlesnakes are one of the main natural predators of California ground squirrels and the squirrels have developed an interesting defense mechanism: the ground squirrels will eat the shed skins of rattlesnakes and then lick themselves and their young, thus covering themselves with rattlesnake scent and confusing a potential rattlesnake predator into thinking it is merely smelling another rattlesnake. Pretty sneaky, eh?
The California ground squirrel has a fairly bushy tail so is sometimes mistaken for the Eastern fox squirrel (a tree squirrel), but has different colored fur and retreats underground instead of up into a tree.
Watch Sam accidentally startle the squirrel into the den!
January 27, 2012
Sam Easterson has caught a relatively unusual occurrence on camera. On New Year's day Sam's camera trap discovered a Common Yellowthroat (Geothlypis trichas) skulking behind one of our sheds (I should add that this is the same shed the opossums have a den underneath). It is relatively unusual only because of the season, this is only the third time a Common Yellowthroat has been sighted here in winter!
New Year's day sighting of female Common YellowthroatAccording to Kimball Garrett, our Ornithology Collections Manager, the Common Yellowthroat is a widespread North American wood-warbler, breeding in marshes and wet meadows and scrublands over most of the continent. In Exposition Park, Kimball usually observes yellowthroats in the Rose Garden, where the dense beds of roses provide good places to hide. Of course we hope that as the vegetation in the North Campus becomes established we'll begin to find them here too.
Same bird caught on camera 14 days laterAll told Kimball has spotted the Common Yellowthroat 66 times in Exposition Park since he began surveying the area in 1984. Sixty-two of those sightings occurred during the bird's fall migration, between 27 August and 2 December. Kimball has also recorded two additional sightings during the bird's spring migration in April. Prior to this year's winter sighting, Kimball has observed the yellowthroat twice in mid-winter – on 27 January 2010 and 6 January 2011. This is why it was a bit of a surprise when Sam's camera trap recorded the visit of a female Common Yellowthroat earlier this month. According to Kimball, "modern technology is clearly better than an old human field ornithologist in keeping track of more secretive birds!" Regardless of the mode of sighting this record is good news. It suggests that the plantings in the North Campus will provide an important habitat that is lacking in the urban core. We are planting dense low vegetation that is the domain of wrens, Geothlypis warblers, various sparrows and other bird species that are rarely seen in your common urban park that is dominated by trees and lawns.Thanks Kimball for your detailed bird records and natural history information of the Common Yellowthroat!
November 29, 2011
Mystery abounds in the North Campus, for who's been leaving scat under the footbridge? I discovered a vast array (about 10 pieces) of scat while I was searching for fungi a few weeks ago, and of course I snapped some pictures to try and identify our most recent visitor.
Who does this scat belong to?
My gut told me the scat belonged to either a Virginia Opossum, Didelphis virginiana, or a Raccoon, Procyon lotor. To get a definitive answer I did two things. Firstly, I sent this picture to Jim Dines, the Museum's Mammology Collections Manager. Secondly, I put Sam Easterson on the project to set up a camera trap.
Almost caught in the act!
The trap that Sam put up over the Thanksgiving Holiday recorded at least one, if not two Virginia Opossums under the bridge! Although, we didn't capture footage of an opossum in the act so to speak, I am pretty confident we've discovered our scat provider! In concurrence was Jim, "You're right that it's probably opossum. They can have such varied diet that their scat can be hard to identify."
On the subject of scat, I have one last thing to show you! Unlike the Virginia Opossum, the Burrowing Owl, Athene cunicularia, we saw last week was caught in the act!
Aside from an in-depth view of owl bowel evacuation, this footage shows how Burrowing Owls are adept at standing on one leg. This isn't a circus trick, it actually allows the bird to keep the other leg warm in the feathers and only allow precious warmth to be lost from one leg at a time!
September 27, 2016
July 20, 2011
Sam moved the camera trap last week. We wanted to see what else we might find in the North Campus. Here's what we found.
I guess the Opossum was like the rest of us totally unaffected by Carmageddon!
How did this dog get into the North Campus at 9:02 on a Sunday morning, when all the gates are locked until 9:30?
June 23, 2011
Last week Sam got an awesome package in the mail, our new camera trap! On Monday afternoon he set it up behind the Butterfly Pavilion to see if it worked. We were also curious to see if we'd capture any interesting images. Boy were we in for a surprise!Night 1: Monday pm-Tuesday am
Our first cat tail caught on camera! We've known for a long time about the feral cats, Felis catus, that live in Exposition Park, but we weren't expecting to capture one of them on camera so quickly.
Just over an hour later this Opossum, Didelphis virginiana, sidled into view. Again we knew they were around as we'd seen their tracks in the mud.Night 2: Wednesday pm-Thursday am
When Sam showed me this picture, I was blown away! I definitely wasn't expecting the trap to capture a juvenile Cooper's Hawk, Accipiter cooperii, in this space. I am very curious to know why it landed here, was it chasing a rat or a mouse, or did it just feel like posing?
I'm pretty sure this is the same cat as in the first image. If it is the same cat, it obviously goes on the prowl after dark. Maybe we'll have to move the camera trap to the bird feeders next time.
Here's another view of an Opossum. We can't be sure if it is the same one, or if there's a family that lives in the park. There's a possibility that there's a den under the shed. I think we'll have to investigate.