August 31, 2012
We've had another visitor at the pond. Since it's a bird, Kimball was kind enough to write this week's post!
"Cooper’s Hawks, Accipiter cooperii, such as this adult, have frequently been recorded by Sam Easterson’s “camera traps” as they drink and bathe at the Natural History Museum’s North Campus pond. These hawks are among the most conspicuous vertebrate predators in urban Los Angeles – a significant turn of events given that this species was on the National Audubon Society’s “Blue List” as recently as the 1970s. The “Blue List” – a sort of early warning list of potential endangerment – included species “suffering population declines or range diminution in all or parts of their range.” Cooper’s Hawk populations have rebounded spectacularly in part because of reductions in the use of certain pesticides, but also because they are now rarely persecuted as the pest their nickname “chicken hawk” alludes to. But the increasing population of Cooper’s Hawks in our region is not without ecological consequences. These hawks, and other species in the genus Accipiter, are bird-eaters – they catch songbirds, doves, and many other kinds of birds by ambushing them with short flights over and through vegetation. We don’t know the extent to which declines in populations of some urban bird species (such as the introduced Spotted Dove, which is now virtually gone from southern California, or the Inca Dove, whose population in the Tucson, Arizona region has plummeted) can be attributed by increased predation pressures by Cooper’s Hawks. Careful observations by scientists and citizens – and Sam’s technological wizardry – may help us better understand the role of predators such as the Cooper’s Hawk in regulating populations of their prey species."Thanks Kimball! Finally, here's some footage Sam's trap captured of the hawk taking a bath in the pond!
August 17, 2012
I admit it! I totally stole the title of this week's blog from my Facebook friend John Acorn, aka The Nature Nut. To be specific, I gleaned this gem of a title from one of his books, Damselflies of Alberta: Flying Neon Toothpicks in the Grass. Today, instead of taking lunch like a normal person, I went out to the pond with Kimball Garrett to survey for adult Odonates. Odo-what? I mean dragonflies and damselflies (the flying neon toothpicks), the jeweled predators of the sky.Among other things, Kimball and I found damselflies for the first time. Yay! Here are some pictures of what we found:
The first ever damselfly to be found in the pond!Pacific Forktail, Ischnura cervula
Flame Skimmer, Libellula saturata, in Kimball's handKimball also thought he saw a Wandering Glider, Pantala flavascens. Thankfully, Sam Easterson had snapped this picture earlier in the morning, confirming the presence of this impressive dragonfly.
Sam's shot of a Wandering GliderSo the list of Odonates in the pond has grown to 5 species:Green Darner, Anax juniusFlame Skimmer, Libellula saturataWandering Glider, Pantala flavascensVariegated Meadowhawk, Sympetrum corruptumPacific Forktail, Ischnura cervulaIn other Odonate news, Black Phoebes love them! Here's the proof, from one of Sam's camera traps:
Tasty dragonfly lunch for a hungry Black Phoebe
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.
March 30, 2012
This week I've been working with Jared Nielsen, one of the Museum's Exhibit Technicians, who also happens to be a DIY (Do it Yourself) enthusiast. With his help we've managed to build and install two nest boxes and launch our first garden surveillance balloon!
Jared installing a nest box in the Shadow Garden
The other nest box in the Home GardenThe nest boxes we chose are made of PVC and designed to be particularly appealing to certain cavity nesting birds such as Western Bluebirds, Sialia mexicana. These birds have been spotted in Exposition Park by Kimball Garrett, the Museum's resident ornithologist, and we hope they'll stick around to use our new nesting sites. The boxes are also designed to be minimally appealing to other species of birds that we don't wish to encourage, such as introduced European Starlings, Sturnus vulgaris, and House Sparrows, Passer domesticus.We ordered the boxes from the Gilbertson Nestbox Company and Jared brought all the materials necessary to assemble and install them in the North Campus. The cost for all materials including the nest box is approximately $30 each. Instructions for installation and how to properly monitor birds that move in are available on the Gilbertson website.I'll keep you posted, and let you know as soon as any birds move in. Of course Sam Easterson, our resident video naturalist is also waiting in the wings. As soon as a nest is built, he will install a video camera and we'll hopefully be able to capture images of eggs being laid and nestlings hatching!As if that wasn't exciting enough, today we launched our first garden surveillance balloon.
Affixing the surveillance camera to the balloonOur garden surveillance balloon is a project Jared discovered through the Public Laboratory for Open Technology and Science. Their Grassroots Mapping project provides instructions on how to build your own balloon mapping kit, or you can purchase a kit for $85 from their website!Jared opted for the DIY approach and sourced all of his own materials, including the 2 meter wide weather balloon and a rental helium tank! Following the Grassroots Mapping instructions, Jared rigged the balloon to carry a camera and tethered it to a 1000 foot long string which he held onto as we walked it around the site. The camera was also adapted to continually take pictures every second until our 16 megabyte memory card was full (about 2 hours). Over the next few days Jared will take all the images and stich them together using a free online software that will create an aerial map of the North Campus gardens. Not only will this map look really cool, it will also help us to keep track of all of the plants in the gardens and see how it changes over time. Yes, we are going to do this again, maybe even every few months!
We needed a lot of help from staff to make sure the balloon didn't float away as we were filling it with helium!(Jesse Daniel, Jared, Briana Burrows, and Karen Ewald)
Karen celebrates a successful launch
Our first aerial view of the North Campus.Can you spot us in the bottom right corner?
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!
December 28, 2011
A few weeks ago, Sam Easterson followed a trail of tin foil and discovered the den of a Virginia opossum, Didelphis virginiana, underneath one of the Museum's storage sheds. Since then he set up camera traps around the den to see what was going on. This is what we found...A night of tin foil escapades. What on Earth are they doing with all the tin foil? Tin foil hats to ward off alien thought control maybe?
All kidding aside, it seems that this opossum has extracted a tasty morsel from inside the shiny package and is taking it down into the den.
Afternoon stroll?The next day, one of the opossums emerges for a late afternoon jaunt in the park, and takes a peek at the camera trap!Running away from Museum security!Can you see the flash light?Doing the Chores Finally, we caught lots of images of the opossums collecting leaves with their tails! Their prehensile tails are a great tool for grasping small objects and are sometimes used for hanging upside down in trees. Though the notion that they sleep hanging upside down is a myth, their tails are not strong enough to hold them upside down for an entire night.
Wait, there's more tin foil!What is in store for 2012? Sam's got a few tricks up his sleeve, which I'm not willing to reveal just yet. Suffice it to say that we're all hoping there will be babies in the spring! Happy 2012!
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 23, 2011
This past Monday a few of us embarked on a real urban nature adventure. We traversed the city streets of Los Angeles to witness one of the coolest nature spectacles I have ever seen in downtown Los Angeles, 6,500 Vaux's Swifts, Chaetura vauxi, spiraling into an old building shaft!
Ghetto bird and swifts share L.A.'s skyline alike!According to Kimball Garrett, NHMLA's Ornithology Collections Manager, these swifts stop in L.A. during their spring and fall migrations to and from their breeding grounds in the Pacific Northwest and their overwintering sites in Mexico and Central America. While in L.A. they gorge themselves during the day on flying insects found in areas such as the L.A. river and Griffith Park, and roost at night in various shafts and chimneys around the city.In recent years the roost of choice for thousands of these birds is the Chester Williams building, on the northeast corner of Broadway and 5th Street, near Pershing Square. The parking structure next door to this building is where myself and a few other Museum staffers found ourselves at 6:00pm on Monday evening. At approximately 7:30 the swirling masses of swifts began entering the shaft. Although it is impossible to count every individual, Kimball was able to estimate the number of birds entering the roost site. They enter the shaft at a remarkably constant rate of about 10 birds per second. We watched birds enter the roost for about 11 minutes (660 seconds), yielding a rough estimate of about 6,500 birds. Thanks Kimball!
Vaux's Swifts spiraling into the Chester building's shaftOf course Sam Easterson was one of our party, he managed to capture this footage of the swifts entering their roost.As a final note, its not all easy living for the swifts. Common Ravens, Corvus corax, have learnt to hang out at the shaft opening and prey on individuals entering their roost site. I managed to catch a picture of this Raven flying away with its dinner!
September 12, 2011
When Tim Bovard, the Museum's taxidermist, told me about getting stung by wasps on the fourth floor patio, I had to investigate, especially since I sometimes eat lunch up there. During a much needed afternoon break from my computer, I went in search of the offenders. What I found on my afternoon foray were some large and impressive nests, definitely worthy of a blog entry. So of course I asked Sam if he would take pictures for me, and I went to work identifying them.
Common paper wasp nest, Polistes exclamansThe species living on our patio are Common Paper Wasps, Polistes exclamans, which have a widespread distribution through much of the southern United States. These insects construct a papery nest from fibers they gather off dead wood or plant stems. Next time you see a paper wasp on a wooden fence realize it might be chewing off tiny pieces of wood which they will mix with their own saliva to make paper! The nests are umbrella shaped and generally built under eaves or porches, or in similarly sheltered locations. Unlike yellowjackets and hornets, paper wasp nests are not enclosed in a papery shell, which give a really good view into the individual cells.
A view into a brood chamber, can you see the larva?Sam was also able to get some great video footage of the wasps at work. In an effort to provide the best video documentation ever, Sam nearly sustained a few stings himself. Luckily the wasps went for the video camera instead!
April 4, 2017