November 10, 2015
On a recent visit to San Pedro, the Natural History Museum’s Kimball Garrett crossed paths with a nonnative red fox (Vulpes vulpes) near the 22nd Street Landing . Although unusual now, red fox sightings were commonplace in many parts of coastal Southern California just a few decades ago.
Photo courtesy of Kimball Garrett
If red foxes aren’t native, how did they get to Southern California in the first place? Not surprisingly, their introduction was anthropogenic, the result of human activities. From 1905 to 1919, red foxes from the eastern US were imported into Orange County specifically for the sport of fox hunting. Simultaneously, the farming of imported foxes for the fur industry was becoming widespread throughout California. More than 100 fox farms existed across the state by the 1940s. Escapees and deliberate releases from both enterprises quickly became comfortable in their new environs, reproducing and expanding their population and distribution. Museum specimen records show that by the 1970s red foxes had become established widely throughout the region, with salvaged road kill specimens collected from North Hollywood, Glendale, the Palos Verdes Peninsula, and nearby beach cities.
Red foxes, like many introduced species that become successfully established, are generalists that easily adapt to new environments. They are capable of surviving—even thriving—in diverse habitats and on widely variable diets. More often than not, however, the success of an introduced species is to the detriment of native wildlife.
The population of red foxes boomed in Southern California in the 1980s and 90s, inflicting ecological devastation along the way. Red foxes actively preyed upon native species, many of which were already in trouble due to habitat loss. This included ground-nesting shorebirds and songbirds, lizards, snakes, rabbits, and native mice. At Orange County’s Seal Beach Naval Weapons Reserve and Bolsa Chica Wetlands, as well as the Ballona Wetlands in Los Angeles County, populations of endangered bird species such as the light-footed clapper rail, the least tern and Belding’s Savannah sparrow, were brought to the verge of extinction. Red foxes were also likely responsible for causing the local extinction of the Pacific pocket mouse from habitats like the El Segundo Dunes.
Efforts by the US Fish and Wildlife Service to eliminate the nonnative red fox were met with harsh criticism by animal rights activists, despite the looming threat to the endangered native fauna. Lawsuits ensued and much time and money was lost defending the effort to eradicate the nonnative predators. In the end, a lower profile program that targeted red foxes in specific areas resulted in a rebound of the native bird colonies in the late 1990s.
In addition to their hunting prowess, red foxes easily spread and thrived in Southern California due to their ability to adapt to just about any environment. While urban infrastructure is an impediment to species like the mountain lion, to the red fox it presents opportunity. Research published in 1999 by Jeff Lewis and Rick Golightly, of Humboldt State University, documented how red foxes in Southern California use flood control channels, freeway underpasses, railroad and highway corridors, and powerline right-of-ways to move around and expand into new territories. They are also comfortable making their dens in culverts, at golf courses and parks, or even alongside busy freeways.
In light of their extraordinary adaptability, why have red fox sightings remained uncommon? One possibility is that coyotes actively suppress and kill red foxes. As coyotes have expanded into urban areas, they are taking over the same niche formerly occupied by the red foxes. It very well might be that the native coyote is succeeding where frustrated wildlife managers couldn’t: eliminating the introduced red fox.
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
May 7, 2013
What you are about to look at is gross! Also, this post is not about L.A. urban nature, it is about Orange County marine nature. But, I contend that some beaches are pretty dang urban and Orange County isn't that different from L.A.–right?
Plus, this is sort of sea monster-ish and therefore awesome, I couldn't resist!
This is not the rotting carcass of a sea monster!
*Note the ribs still covered with rotting flesh, and the exposed vertebrae. Jim said it smelled pretty awfull.
So, what is that mass of rotting flesh? According to Jim Dines, our excellent Mammalogy Collection's Manager, it is a beached beaked whale.
Here's the account Jim wrote up for our Research & Collections newsletter:
"On April 30th, Dave Janiger and Jim Dines retrieved the decomposed carcass of a Cuvier’s beaked whale (Ziphius cavirostris) from Crystal Cove State Beach in south Orange County. Beaked whales are uncommon in museum collections and much about these unusual cetaceans remains unknown, making this new specimen an important acquisition for the marine mammal collection. As recently as 2002, a new species of whale, Perrin’s beaked whale (Mesoplodon perrini), was described using specimens from our collection."
Before this week, I had never even heard of a beaked whale. Apparently, this isn't that surprising as they are fairly rare and elusive. They, like dolphins and sperm whales, belong to the Odontoceti group, aka the toothed whales. But, there are only 21 known species in the world, some of which have only been described from their washed-up remains! Wild encounters with some of these species are considered a rare treat, even so for the scientists that spend their lives studying them. This is because they are amazing divers and spend extended periods of time diving to great depths in the open ocean. One way scientists distinguish between the species is through an interesting adaptation male whales have on their head. As a male beaked whale becomes an adult, teeth erupt out of their lower jaws and seemingly jut out of their heads, sort of like horns or antlers in terrestrial mammals. Just like male deer or moose use their antlers to fight over mating rights, beaked whales use their erupted head teeth (fyi, that is not the scientific term) to do the same. If I'm ever lucky enough to encounter live beaked whales, I hope beyond hope that I'll get to witness two males battling it out with their awesome teeth. Just imagine!
Arnoux's beaked whale
Photo courtesy of Soler97
May 31, 2012
I've been spending a lot of time thinking about rats. Thankfully, it is not because I have a problem in my apartment! Unfortunately, for many people in L.A., rats are a serious pest, and it's not just one type of rat. The most serious rodent offenders in our cities are the brown (aka Norway) rat, Rattus norvegicus, and the black rat, Rattus rattus.
What species of rat is this?
Here on the North Campus we have camera trap images and footage of rats hanging out underneath the bridge. But what type of rat is this? Since Jim Dines, our Mammalogy Collections Manager, wasn't available, I decided to try and figure it out myself. Doing a Wikipedia search for brown rats, I came across a nice diagram that helped me to make an identification. What species do you think it is?
Comparison of the physique of a black rat, Rattus rattus,
with a brown rat, Rattus norvegicus, from wikipedia
Using this diagram I looked closely at the ears and the eyes of the rat. Based on the relatively large size of the ears and the eyes, I determined the above image was of a black rat rather than a brown rat. I showed the image to Jim and he confirmed that it was indeed a black rat!
Black rat (top) and brown rat (bottom) from the Museum collection.
Note the tail to body length ratio.
Regardless of the species, why do people hate rats? As I referenced in the introductory paragraph, rats are sometimes pests in our homes, but what exactly do people think about rats? I did a Google search for, "why do people hate rats," and this is what I found. "Cute or not they're germ-ridden disease carrying vermin who in addition, can cause untold damage. THAT'S WHY." I also found this: "Rats are pests to humanity, but I personally believe that people especially hate rats because they subconsciously identify with them and see them as a reminder of themselves." Finally, someone else wrote: "A lot of rat-hatred goes back as far as plague. Rats were responsible for the disease that killed thousands of people."
But, is plague a worry for us today in L.A.? Not really here in the city (I hear a collective YAY)! Firstly, according to the Centers for Disease Control and Prevention the last cases of urban, rat-associated plague occurred in L.A. in the 1920s. However, plague is present in L.A. County, and the principal mode of infection is from infected fleas living on wild rodents in rural areas. These rodents include California ground squirrels (remember the recent blog post?) and chipmunks! According to L.A. public health officials, "the major threat of plague to humans is in the rural, recreational and, wilderness areas of the Angeles National Forest, as well as the Santa Monica and San Gabriel Mountains." But, before you swear off recreating in our lovely parks forever, know that there have only been four cases of the plague in L.A. since 1979, none of which were fatal (another YAY for antibiotics and modern medicine).
P.S., Plague is actually caused by a bacteria, Yersinia pestis, that lives in the blood and other bodily fluids of fleas, rodents, and other mammals.
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!
March 30, 2017
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!
June 15, 2011
What's For Dinner (and the Unintended Consequences of Every Introduction)?
The Eastern fox squirrel, Sciurus niger, was imported to Southern California in 1904 by veterans of the Civil War and Spanish American War, at the time living at the Veterans Home in West Los Angeles. The war veterans mostly came from the southern US (e.g., Tennessee, Kentucky) and kept as caged pets tree squirrel native to their home states. Perhaps it is apocryphal, but I've heard that the squirrels weren't just pets, they were also used in that old-time favorite—squirrel stew!
Whatever the reason for keeping the squirrels, eventually an overzealous hospital administrator noticed that they were being fed table scraps and, deeming this illicit provisioning a misuse of government support, turned the squirrels loose. The fox squirrels did quite well in their new habitat and it wasn’t long before they spread throughout the region.
Today we find Eastern fox squirrels from Oxnard to Ontario and from Santa Clarita to south Orange County. As their range has expanded, the fox squirrel has increasingly come into contact with the Western gray squirrel, the native tree squirrel that lives in the foothills and mountains of Los Angeles. Biologists are very interested in studying the ecological effects of these two species as they come into contact, including possible displacement or hybridization.
Here in Exposition Park we have a large and feisty population of these squirrels. At lunchtime they can often be seen wrestling French fries and sandwiches out of field trippers' hands. Here's some footage Sam Easterson captured of one of them eating lunch crumbs off the sidewalk.
In addition to this footage Sam is trying to capture some non-traditional footage for our new Nature Lab exhibit. We're hoping to show you nature like you've never seen it before, and Sam thinks this peanut cam might help! He says, "I like the idea of the squirrel shooting footage. Maybe he/she will take the peanut up a tree or even bury it underground." Whatever happens, I'll be sure to keep you all in the loop as we try out the peanut cam.
Sam's prototype peanut cam!
Thanks Jim Dines, Mammalogy Collections Manager, for all the Eastern fox squirrel facts!
April 28, 2017