Projects in the Field

Projects in the Field

2

Not So Blue: Blue Mountain Koalas

This male was located just on the western edge of the Blue Mountains. Photo credit:  John Eggenhuizen

This male was located just on the western edge of the Blue Mountains. Photo credit: John Eggenhuizen

For the past few years my research with koalas in Australia has expanded to focus on koalas living in the states of Victoria and New South Wales (NSW). These regions are south of Queensland, where St. Bees Island is located, and are at the middle to lower portion of the koalas’ home range. We are studying koalas in these parts to further our knowledge of this species and to really start comparing them across their entire habitat. Their entire home range is about 1,800 miles (3,000 kilometers), and with every new project and section that we venture into we get more data on the interesting lives of koalas.

This past November I had the pleasure of heading off to Australia again to meet with colleagues studying koalas in the wild and to see one of these new locations for our koala research, the Blue Mountains in NSW. The Blue Mountains are a World Heritage Site and historically were home to abundant koala populations prior to the fur trade in the early 1900s. Today, koalas in this region are harder to find but may be a significant and genetically valuable population (and, no, the koalas are not blue!). The rough terrain and sweeping vistas that make this area a wonder to behold also make it difficult to track koalas in traditional ways.

The Blue Mountains are located in New South Wales, Australia. Photo credit: Kellie Leigh

The Blue Mountains are located in New South Wales, Australia. Photo credit: Kellie Leigh

In order to get in and find koalas, we are developing less traditional methods to track them. I went out to the area with Dr. Kellie Leigh of Science for Wildlife Inc so that we could assess the area and see where there would be potential spots for koala research. We didn’t see koalas while I was there, but what we did see were some signs of koalas, like claw marks on trees. On the heels of our trip there was a koala count: they have an app for that—Great Koala Count! This citizen science survey gives locals and visitors alike, in areas such as the Blue Mountains, the ability to record the presence of koalas. Some very interesting results came in with sightings of koalas in areas where koalas were thought to no longer be found. These sightings have helped Dr. Leigh narrow her search of where to begin in this vast koala habitat.

With my collaboration with Dr. Leigh, we hope to use all our knowledge of koalas’ behaviors as well as their scent to start training a koala-tracking dog to further our efforts to find these potentially elusive koalas in the Blue Mountains. This will take the help of our San Diego Zoo colony of koalas, as we are hoping to use their chemical profiles to facilitate the choice scents in order to train this dog to assist researchers in the Blue Mountains. Once we find koalas, they can be fitted with satellite GPS collars so the fieldwork that Dr. Bill Ellis and his team have done on St. Bees and continue to do in the Brisbane Valley area can be expanded. Through this research we are able to further our commitment to ensuring that koalas are around in their natural habitat for everyone to experience for generations to come.

Jennifer Tobey is a behavioral biologist in the Behavioral Biology Division of the San Diego Zoo Institute for Conservation Research. Read her previous post, A Koala Career.

4

Climate Change: Polar bears, Sea Ice, and Beyond

Kalluk enjoys last year's snow day at the San Diego Zoo.

Kalluk enjoys last year’s snow day at the San Diego Zoo.

Climate change is back in the news and, unfortunately, the news has not been good. A number of recent reports indicate that carbon dioxide in our atmosphere has reached unprecedented levels. At over 400 parts per million, we have reached a number that would have seemed unimaginable just decades ago. But while the scale of this problem is immense, the real power for changing the current trend is within each of us. The choices we make—what we buy, how we spend our time—can lead to dramatic differences in our carbon footprint. It is possible to reverse the current trend if we all commit to changing our daily habits.

There is a vast array of information now available that outlines the many-faceted ways that the changing climate will impact people and ecosystems all over the world. From extreme weather to climate warming, the reach of climate change is broad. And the reason our climate is changing is known: human activities have driven the release of unprecedented levels of carbon dioxide into the Earth’s atmosphere. Carbon dioxide (CO2) is a greenhouse gas that effectively blankets the Earth, increasing the amount of heat that stays in our atmosphere. And while we typically associate carbon dioxide emissions with the burning of fossil fuels, such as gas and coal, there are other sources as well that are not as well known. One of the largest contributors to atmospheric carbon is deforestation. Each year, the burning and clearing of tropical forests contributes over 2 billion tons of carbon pollution to the atmosphere.

At the San Diego Zoo, our mission is to connect people to wildlife because that connection can be a powerful force for conservation. I can speak from personal experience as to the power of that connection. Destined for medical school, my career path shifted dramatically because of a chance connection with wildlife. For me, that connection started with the polar bear, a species whose plight has provided some of the defining images associated with climate change, a species whose future we hold in our hands.

As a graduate student, my first field season was spent working out of a remote field camp on the western Hudson Bay, about 15 miles east of Churchill, Manitoba (a.k.a. the Polar Bear Capital of the World). This area, so nicknamed because of the large number of polar bears that congregate there in the fall, was also home to an incredible array of wildlife, including Arctic nesting birds, large herds of caribou, and beluga whales. While polar bears are most numerous and visible during the fall, the bears actually start coming ashore during the summer as the ice on the Bay begins to melt out, and the bears are forced ashore to begin a long fast.

Our field research was primarily done on foot, with miles and miles of walking over the course of the long Arctic summer days, and the possibility of bumping into a polar bear meant that safety measures were taken seriously and practiced regularly. The most basic and important safety measure we had while walking in the field was to scan the horizon with binoculars every few minute, in hopes of spotting any polar bears in the vicinity while they were still a good distance away. On the day I saw my first bear, it was relatively early in the season for polar bears, but the ice had begun to break up on the Bay, a harbinger of polar bears to come. Scan after scan, I saw nothing and continued with my work. And then suddenly, I looked up, and saw a young male bear easily without binoculars, less than 50 feet away. How long had he been following me? Luckily, I was able to make my way safely back to camp. And while it was truly scary to see a bear so close, it was also an event that left an enormous impression on me. It initiated my love of the species and cemented my passion for conserving wildlife and wild places.

Around that same time (the mid-1990s), biologists studying polar bears in the Canadian Arctic documented changes that were occurring within that population of polar bears. These scientists found that reductions in reproductive parameters were correlated with the warming air temperatures that had been documented between 1950 and 1990 and, most importantly, with an increasingly long period where the Hudson Bay was ice free. Because polar bears are completely dependent upon the sea ice for their survival, the directional trend toward less and less ice was of great concern. Twenty years later, I am happy to say that the polar bear is one of the species that I get to study, but saddened to say that the Earth’s CO2 emissions have continued to increase and that the impacts of climate change on polar bears have intensified. No other species better illustrates the impact of climate change on wildlife. Like a real-life version of the game “Break the Ice,” the polar bear’s habitat is disappearing, the ice literally melting at their feet. Their fate is in our hands.

Chinook and Kalluk have been breeding for the past couple of weeks, and we are hopeful, as in years past, that this breeding season will result in the birth of a polar cub in the fall. We will monitor Chinook closely for behavioral and physiological signs of pregnancy and learn as much as we can about the reproductive biology of these amazing animals. Keepers, researchers, and visitors alike have an amazing opportunity to observe our bears in the water and on land at the San Diego Zoo, and in so doing, learn about climate change and the impact that this human-driven change is having on wild polar bears and the Arctic sea ice environment. Polar bears exemplify the role of “conservation ambassadors,” and it is hard to deny the impressive nature of their strength, intelligence, and adaptations to life on the frozen Arctic Ocean.

Climate change may sound like old news to some. Images of polar bears stranded on ice floes were once a common sight in the popular press, but like most news stories, many people have moved on. Unfortunately, climate change has not gone away, and the negative impacts of sea-ice losses on polar bears continue to eke away at their once-pristine Arctic home. I am hopeful that the reemergence of climate change into the news cycle will invigorate people’s interest in doing their part to reverse the trends in CO2 emissions. I am hopeful also that we all seek those connections to nature and wildlife that are so important for engaging us in conservation issues. We can all make a difference.

For those who love our polar bears, and for those who are interested in learning more about how climate change is impacting the species’ Arctic sea ice habitat, I recommend visiting the National Snow and Ice Data Center (NSIDC) website. This page provides daily updates on sea ice conditions in the polar regions, as well as year by year interactive graphics of the dynamic changes in sea ice extent.

Megan Owen is an associate director with the San Diego Zoo Institute for Conservation Research. Read her previous post, Our Panda Conservation Program.

11

Bear Courtship

This camera-trap photo shows a male Andean bear, left, being rebuffed by a female Andean bear.

This camera-trap photo shows a male Andean bear, left, being rebuffed by a female Andean bear.

To improve giant panda captive breeding programs, researchers have carried out numerous investigations of how male and female giant pandas communicate with each other, and how their hormone profiles change independently, and in response to each other. Applying this knowledge has contributed to the success of giant panda captive breeding efforts, which are now based on more information than is available for any of the other bear species.

In the dry forest of northwest Peru, where we’ve been working with the Spectacled Bear Conservation Society, there appear to be some relatively predictable cycles. Food for the Andean (spectacled) bears appears to be scarce for most of the year, so some of them turn to eating pasallo trees, and all of them gradually lose weight. Then, when the fruit of the sapote is available, the bears focus on that fruit and gain weight. We’ve suspected that the bears mate during that same season.

Although there isn’t much information on what courtship looks like among wild Andean bears, we suspect that males crisscross the landscape, looking for females that are in estrus and so may be willing to mate, or which will be ready to mate in the near future. Once a male locates a female, probably through some sort of olfactory communication that is similar to but different from the means used by giant pandas and polar bears, we think a male will then follow that female, trying to determine when it’s safest to approach her, while chasing off any other males that might also try to mate with her.

Like all bears, Andean bears are not social as adults, but obviously a male and female have to respond positively toward each other in order to mate. We believe that in Andean bears, like giant pandas, the coordination of reproductive readiness (and willingness!) is influenced by hormones, chemical cues, and behavioral interactions. A male has to get the timing right. If he approaches the female at the wrong time, she’s likely to vocalize loudly at him, box his ears, run away, or any combination of those alternatives. We’ve recently retrieved photos from a camera trap in the dry forest that suggests that one male, at least, didn’t quite time his approach correctly!

Russ Van Horn is a scientist with the San Diego Zoo Institute for Conservation Research. Read his previous post, Bear Ambassador Learns Importance of Plants.

4

Saticoy Flies into the Wild!

Saticoy (purple #36) receives his transmitters before his release.

Saticoy (purple #36) receives his transmitters before his release. Photo credit: Devon Lang Pryor, U.S. Fish & Wildlife Service

We have some exciting news: Saticoy, everybody’s favorite California condor who hatched and grew up on the San Diego Zoo Safari Park’s Condor Cam in 2012, has finally been released to fly free in the wild! Saticoy was the first California condor to hatch, on March 10, 2012, while thousands of excited viewers watched live on Condor Cam. His parents (father Sisquoc and mother Shatash) did an amazing job raising him for over five months until he left the nest.

On April 11, 2013, we transported him to the Bitter Creek National Wildlife Refuge in southern California with two other young condors to be socialized in a pen before being released. The young birds were kept in this flight pen throughout the summer and into the autumn so that they could become familiar with their surroundings before they were released. They were able to acclimatize to the weather and wind. Also, the 60+ other condors already flying free in this region were allowed to meet the new, young release candidates through the flight pen’s wire. When the young birds were released, they weren’t complete strangers to the free-flying residents.

The two condors who accompanied Saticoy from the Safari Park (Nechuwa, #637, and Sukilamu, #643) were the first two birds released from the flight pen. They were released on October 22, 2013. The U.S. Fish & Wildlife Service field biologists observed these two for a while to make sure they were socializing well into the wild flock before releasing any of the other young birds. After these two youngsters were okay, it was Saticoy’s turn.

Saticoy feeds at a carcass with other condors; one is Sukilamu (purple #43), another Safari Park condor.

Saticoy feeds at a carcass with other wild condors. Photo credit: Devon Lang Pryor, U.S. Fish & Wildlife Service

Saticoy (#636) and a young female (#628) from the World Center for Birds of Prey in Boise, Idaho (another of our valuable partners in the California Condor Recovery Program) were released together on November 20, 2013, and flew away from the flight pen. Then some bad weather hit the area for the next two days. By November 23, 2013, the fog had cleared, and the sun was shining. That afternoon, both #628 and Saticoy had found their way back to the flight pen and began feeding with the free-flying condors. One of the field biologists said that the two young condors may have set a record in returning to the release site and fitting in with the wild birds so quickly!

Saticoy was also observed perching and roosting in big snag trees with other birds those first few days. Usually, the field biologists find newly released birds on the ground or perched in small trees or shrubs before they make it up to the roost snags.

As you can see, it takes a lot of time, effort, and people to prepare young condors for a release program. Without help and enthusiasm from people like you, none of this would be possible. All of us at the Safari Park (including all of the condors!) thank you so much. It appears that Saticoy is off to a great start at Bitter Creek National Wildlife Refuge and is learning his way around. We couldn’t be happier for him!

Many thanks to Devon Lang Pryor, U.S. Fish & Wildlife Service Biological Science technician, for providing us with an update and photos of the release!

Ron Webb is a senior keeper at the San Diego Zoo Safari Park. Read his previous post, The Condors Next Door.

3

Volunteers Help Desert Tortoises

Volunteer Kimi Sharma won a contest for most volunteer hours worked in June: 71 hours!

Volunteer Kimi Sharma checks on a resident of the Desert Tortoise Conservation Center.

I’m always amazed to see volunteers bouncing into the Desert Tortoise Conservation Center at 5 a.m. to start the day. Most of our volunteers drive long distances to give of their time and help the tortoises. We had wonderful volunteers this season, all very dedicated! They have already put in over 600 hours so far this season!

Our volunteer coordinator, Lori Scott, did a great job coordinating, orientating, and keeping up with the various schedules of the volunteers. Lori’s job was to also make sure they felt appreciated and were gaining a valuable experience. Kimi Sharma won a contest for most volunteer hours worked in June: 71 hours! Before Kimi left to head back to school in Boston, she had acquired 155.5 hours of volunteer work. Kimi was kind enough to bring all of us lunch on her last day, which we appreciated very much…I don’t think she really wanted to leave!

The volunteers work really hard in the hot summer sun right along with staff watering, feeding, and helping us care for all the desert tortoises on site. We appreciate every hour the volunteers give of their time to help out the tortoises they care for. Volunteers help us out tremendously, and we couldn’t do our job without them!

We are now gearing up for translocation season and are always looking for volunteers to help out—it’s such an awarding experience! If you are in or going to be in the Las Vegas area and wish to help with volunteering, email us at DTCC@sandiegozoo.org.

Angie Covert is a research coordinator at the San Diego Zoo Desert Tortoise Conservation Center. Read her previous post, Internship at Desert Tortoise Conservation Center.

52

Polar Bears, Climate Change, and Mi (Ton Teiow)

Tatqiq's wild counterparts need more snow days.

Tatqiq’s wild counterparts need more snow days.

Mi Ton Teiow, the whimsical “bear” ambassador for the IUCN’s Bear Specialist Group (see post A Whimsical Bear Ambassador Arrives), has continued his travels, along with staff from the San Diego Zoo’s Institute for Conservation Research. With these travels, Mi is gaining experience in the multi-faceted world of bear conservation, which often includes extended periods of sitting and talking! While Mi might be anxious to get outside and do field research, our bear ambassador also understands that bringing people together to discuss the nuts and bolts of bear conservation is an important, and necessary, part of the process.

Recently, Mi traveled to the Toledo Zoo to sit in on the annual meeting of the Polar Bear Species Survival Plan (SSP). The role of the SSP (for polar bears or any other conservation-dependent species) is to bring together experts from zoos around the country to ensure that the members of the zoo community are being as effective as possible in supporting conservation efforts for the species. The focus of this SSP meeting was to enhance the synergy between zoo-based research, field-based research, and effective polar bear conservation. Speakers from the U.S. Geological Survey and researchers from the San Diego Zoo, Cincinnati Zoo, and Memphis Zoo presented overviews on current research and results, as well as ideas for the future.

Mi (center) and Megan (standing second from the right) pose with other members of the Polar Bear SSP.

Mi (center) and Megan (standing second from the right) pose with members of the Polar Bear SSP.

While listening in on discussions regarding conservation research, Mi also learned about the primary threat to polar bears: greenhouse gas emissions resulting from human activities have led to measurable and rapid changes in global climate patterns. The degree and character of these changes is not uniform, and different regions, ecosystems, and species are being impacted in different ways. When it comes to climate warming, scientists have documented the greatest degree of warming at the Earth’s polar regions.

This is bad news for the polar bear, because increases in both air and ocean temperatures in the Arctic have resulted in rapid losses of sea ice over the past several decades. Polar bears depend on the sea ice for their survival. Without the sea ice, polar bears cannot feed themselves or reproduce successful. This dependence on sea ice has left polar bears vulnerable to extinction in the face of climate change.

While the situation is critical for polar bears, it is not hopeless. Each and every one of us has the ability to help save polar bears by making small changes in our daily lives, such as turning off unneeded lights and riding our bikes more, to reduce our carbon footprint along the way. Because zoos have tremendous access to a large number and wide range of people, we play a critical role in polar bear conservation. As a conservation organization, we are responsible to get the word out, and we are happy that we were able to share our work with ambassador Mi Ton Teiow.

Megan Owen is an associate director for the San Diego Zoo Institute for Conservation Research.
Read about Ambassador Mi Ton Teiow’s previous adventure in Black Bears: A Conservation Success.

33

Pandas: How Far We’ve Come

Su Lin is at home in China.

Su Lin is at home in China.

Traveling to China is always an adventure, and the prospect of seeing old friends and long-time colleagues at the International Panda Symposium in Chengdu was exciting! The symposium was truly a great opportunity to listen to scientists from around the world share their updates on current research projects, overviews of the incredible successes for panda conservation achieved over the last 20 years, and important directions for our conservation research efforts for the years to come. We also had an opportunity to visit the Chengdu Research Base for Giant Panda Breeding, where we saw the many panda cubs and young adult bears that have been born there in recent years. There is still so much to learn regarding pandas and their conservation, but it is amazing how far we’ve come in the past 20 years!

On this trip I was also able to check in with staff from Wolong and Bi Feng Xia regarding the status of the San Diego Zoo-born pandas. Having watched their births, first days of life, and years of development into healthy sub-adults, I think we all love to hear how Hua Mei, Su Lin, Zhen Zhen, and Mei Sheng are doing.

Hua Mei, our first-born cub, continues to show that she has her mother’s “good-mom” genes. Now 14 years old, she produced another cub (a male) on July 18, 2013, at Wolong, making her the mother of 10! Both mother and her newest cub are doing well.

Eight-year-old Su Lin had a normal estrus this past spring at Bi Feng Xia and mated naturally several times but did not produce any cubs this year. Regardless, she is doing well and living at Bi Feng Xia. Ten-year-old Mei Sheng mated naturally this year at Bi Feng Xia, too, but we don’t know yet whether he has sired any cubs, as DNA tests are not performed right away to determine fatherhood.

Little Zhen Zhen, now six years old, is currently weighing in at a robust 220 pounds (100 kilograms)! She mated in 2013 and produced a cub that, sadly, did not survive. Zhen Zhen is also living at Bi Feng Xia and doing well.

Megan Owen is an associate director for the San Diego Zoo Institute for Conservation Research. Read her previous post, News about Zhen Zhen.

1

Braving Chilly Nights for Kangaroo Rats

A trap is opened and baited adjacent to an Stephen's kangaroo rat burrow.

A trap is opened and baited adjacent to an Stephen’s kangaroo rat burrow.

6:36 p.m. - The traps are set. Four of us have opened and baited them with millet seed, and all we can do now is wait and hope that they are enticing enough for some endangered Stephens’ kangaroo rats to go inside. We are trapping these k-rats at an experimental restoration site in Temecula, California, to see how the species is doing three years after our initial translocation and restoration efforts (see post, No Night-lights for Kangaroo Rats). As the sun goes down, so does the temperature, and we head to the truck to shield us a bit from the cold and crisp wind.

8:30 p.m. - My first shift to look and listen for coyotes begins. We operate in shifts so that we all get a chance to sleep at some point in the night. Our trap sites must be constantly monitored for coyote presence. They are a wily species and take any opportunity to try and pry one of our precious rats out of its trap for a snack. Can’t they find a species that’s NOT endangered to eat for dinner?!

Researchers collect data on a trapped Stephens’ A kangaroo rat is released back to its burrow.

Researchers collect data on a trapped Stephens’ kangaroo rat.

The coyotes themselves move silently across the grassland, so we vigilantly listen for their shrill yips or the rattling of a trap being disturbed by wild paws. The clouds have moved in, so the night feels even darker and colder than usual. If the temperature drops below 50º Fahrenheit (10 degrees Celsius), we will need to cease our trapping effort for the safety of the animals. I am hoping it stays well above that for the sake of us humans as well! I walk around the site and turn on my flood lamp; the beam of white light shines across our site. I scan all around us. No yellow eyeshine from coyotes, only the silver of our traps and the bright pink from our flags labeling the locations of kangaroo rat burrows.

11:27 p.m. – I feel a nudge on my arm. “Come on,” a voice says, “it’s time to check the traps.” I had taken full liberty to nap while someone else was on coyote watch duty. The cold air on my face is a brutal contrast to the warmth of my sleeping bag. To close my eyes again for just a few more minutes would be heavenly, but it’s time to check our traps and see what we got. Luckily, sleeping upright in a car is never too comfortable, so I welcome the opportunity to stretch my legs, even if it means being out in the cold for a while.

Working in the dark, researchers check to see if any kangaroo rats have been trapped.

Working in the dark, researchers check to see if any kangaroo rats have been trapped.

11:35 p.m. - Our first Stephen’s kangaroo rat of the night! It’s #2364, as indicated by the two small metal tags in its ears. After noting the capture on our data sheet, we let him go. Kangaroo rats are a super-docile species, and I can’t help but giggle a bit when, upon their release, they jump around our feet for a minute before scurrying back into their burrows.

12:41 a.m. - Finished our first trap check. Ready for another nap before our next and final check at 3:45 a.m.

1:48 a.m. – I’m awakened by a gust of cold wind hitting my face. My makeshift sleeping bag fort built precisely to prevent this from happening has failed me! Granted, it was propped up only by the brim of the baseball hat I am wearing, so it was bound to happen eventually. I reconstruct my makeshift fort the best I can and try to get some more sleep.

A Stephens’ kangaroo rat has a metal ear tag for identification.

A Stephens’ kangaroo rat has a metal ear tag for identification.

2:15 a.m. - Second coyote-watching shift of the night! Luckily for us, no coyotes tonight. :-)

3:43 a.m. - That terrible nudge again indicating it’s time for our final trap check. I didn’t think anything would be more difficult than getting up the first time, but I was wrong. It’s only gotten colder, and my hands turn numb as I begin picking up the cold traps and closing them for the night. They’ll be open and set again tomorrow evening for another round of trapping. We check and double-check that all the traps are closed. I’m freezing, even with my two long-sleeved shirts, down vest, and two fleeces on. How do these tiny mammals manage to stay warm in the night? Imagining them in their cozy little burrows underground makes me a bit jealous as I dream of a bed with a big duvet to curl under.

6:33 a.m. – All the traps have been checked and closed, and we begin the drive back to our hotel.

6:58 a.m. – Like a bunch of sleep-deprived zombies, we all shuffle into the hotel lobby. The smell of hot coffee and fresh waffles fills the air as guests enjoy their breakfasts. They must be thinking we are a group of vagrants hoping to score a free continental breakfast as we haul in with our warm clothes on and sleeping bags in our hands. Right now, all I want is some proper sleep—the kind one has in a bed, not the front seat of a truck! I need to rest up, because we still have one final night of trapping ahead of us. It is a grueling schedule, but we are all happy to work it so as to help conserve this amazing grassland species.

Susanne Marczak is a research technician for the San Diego Zoo Institute for Conservation Research. Read her previous post, Banding Burrowing Owls.

3

What’s in Your Backyard?

A scorpion is caught under UV light.

A scorpion is caught under UV light. Photo credit: Dr. David Aveline

The school year has started, and I’m back to student life in Los Angeles, where I’m starting the third year of my Ph.D. at UCLA. It really isn’t too far from the costal sage scrub in San Diego County where I’ve spent the last few months in the field studying the Pacific pocket mice (see Up All Night with Pocket Mice), but it feels worlds apart. For starters, I’m back on a normal schedule—I’m awake during the day and get to sleep at night! What a luxury. But being up during the nights, and hiking around outside, is a very different experience than anything I had been used to.

I have always been a little afraid of the dark—and extremely afraid of spiders!—so doing nocturnal fieldwork was never something I envisioned. Actually, it wasn’t something I had ever even thought about existing, let alone doing. But when the opportunity presented itself, I jumped right in and have become fascinated with what is happening when most of us are normally sleeping!

Many mammals are active at night. There are about eight species of rodents I regularly see in the coastal sage scrub along with tons of rabbits. Coyotes are also very busy at night; we hear them yipping and howling so often it has become a normal part of the sound landscape. Other carnivores like bobcats and mountain lions are up during the night. I haven’t spotted any myself, though I have caught a few deer in my headlamp. They have huge eyes that appear to glow bright green when the light hits them. Most nocturnal vertebrates have this eyeshine, which is caused by a reflective layer called the tapetum in their eye behind the retina. This allows light to hit the visual censor twice; once when it passes into the eye and once when it reflects off this extra layer, which lets them take maximum advantage of the available light. Humans do not have the tapetum layer, though cats and dogs do, allowing them to see much better in the dark—and sometimes giving them crazy eyes in photos taken with a flash!

In addition to mammals, owls are around during the night. They hunt rodents, so we often see them in areas where we are working. Owls have unique feathers and a wing structure that allow them to fly silently. I don’t often think of birds making a lot of noise with their wings, but it is very startling when an owl passes close by and there was nothing to warn you it was coming. This stealth tactic helps them hunt unsuspecting prey!

A tarantula hawk carries away its latest catch: a tarantula!

A tarantula hawk carries away its latest catch: a tarantula!

There are also plenty of creepy crawlies out at night. So many scorpions! We quickly discovered that scorpion burrows look a whole lot like pocket mouse burrows. Scorpions fluoresce under a UV light (black light), which we carry around with us to help identify tagged mammals. It’s amazing how much more visible they are when they are glowing bright green! Another fun fact about scorpions is the mothers give live birth to the young (called scorplings!), which then ride around on her back until their first molt, when they gain some protection from predators and can regulate their body moisture.

The most bizarre and (warning!) terrifying creatures I’ve encountered, though, are tarantula hawks. Tarantulas themselves are fairly common at certain times of year, and, while they can have a painful bite, are not particularly dangerous to humans and not at all a problem unless provoked, like being picked up or handled. Tarantula hawks are parasitic wasps that have glossy black bodies, bright orange wings, and a very menacing stinger. The female wasp captures and stings a tarantula, paralyzing but not killing it, and drags it back to her burrow. She lays an egg on the spider’s abdomen, and when the larva hatches, it burrows into the spider and feeds on it, leaving the vital organs so the spider stays alive. After a few weeks, the wasp larva pupates and eventually becomes an adult and emerges from the spider’s abdomen. I actually witnessed a tarantula hawk dragging a paralyzed tarantula toward her burrow!

These are things I imagine in the tropics, in exotic places far away. But this all goes on nightly, right here in southern California! After all these months in the field, I’m much more comfortable being outside at night, but I also appreciate nature for being both more fascinating and horrifying than ever before.

Rachel Chock is a graduate student and volunteer with San Diego Zoo Global’s Pacific pocket mouse project.

6

Banding Burrowing Owls

A chick is banded with its new identifier, 48X.

A chick is banded with its new identifier, 48X.

This summer, I had the opportunity to assist with the San Diego Zoo Institute for Conservation Research’s western burrowing owl banding effort in San Diego County. A team of researchers worked this spring and summer to trap, band, and observe burrowing owls in South County to monitor the population in the area (see My Summer Staycation: Burrowing into Owl City. The bands serve as unique identifiers and allow us to track individual birds over the course of their lives, monitoring such things as survivorship, breeding success, and home range. For the previous two years, I have been researching California ground squirrel and burrowing owl habitat requirements in San Diego County grasslands, so it was very exciting to finally participate in some work with the actual owls.

On a summer afternoon in late June, we arrived at our site. We pulled off the main road to a place where we could observe the owls’ behavior without disturbing them. We set up our scope and saw them: two adults hanging out by a California ground squirrel burrow they had chosen as their nesting site earlier in the year. The chicks were hidden inside the burrow.

We take morphological measurements of a burrowing owl chick.

We take morphological measurements of a burrowing owl chick.

It was especially meaningful for me to help out with trapping and banding the chicks at this site, as I had visited this location earlier in the year to conduct ground squirrel surveys and gather habitat data and soil samples. On our last day of ground squirrel surveys here in April, we had seen a male burrowing owl using one of the squirrel burrows. I wondered at this moment if this was that same bird I had seen months before, now paired with a female and with chicks of his own.

As we approached the nesting burrow, both adults flew away, in an attempt to distract us from their chicks, and continued to keep a close watch on what we were doing. We used burlap sacks to block all but the main burrow entrance at the nest, and then placed a one-way door trap at that entrance. While the chicks could exit the burrow and enter the trap, they would be unable to leave the trap once inside.

We returned a short time later to find three burrowing owl chicks inside the trap—success! Carefully removing the chicks from the trap, we placed them in a pet carrier so they would be more comfortable as they waited to be banded. During the banding process, we took morphological measurements such as weight, wing length, bill length, and tarsus height and length. A small blood sample was also taken from the birds for genetic analysis. We moved quickly so the chicks could be returned to their burrow as soon as possible.

Upon their release, the chicks scurried back into their burrow with their new bands on. I hope they will survive the rest of the non-breeding season, and we’ll see them again in the spring—maybe with chicks of their very own!

Susanne Marczak is a research technician with the San Diego Zoo Institute for Conservation Research. Read her previous post, Citizen Science: Engaging People in Conservation Research.