Observing Behavior in the Wild


One of our camera traps caught this deer mouse heading for a burrow.

My favorite part of the fieldwork I do (see: A Night with the Pocket Mouse Field Crew)  is watching the pocket mice, kangaroo rats, and other small mammals in the wild. I love releasing them from a trap and watching them take a sand bath, or dig up a cache of seeds they buried previously, or sometimes dive into the closest burrow and get chased right back out by its owner who was already inside.

While the reward (and often the data!) of an animal behavior study is observing your subject do what it does, figuring out how to make the observation can be one of the biggest challenges. You don’t want your presence to affect what the animal is doing—unless you are observing their response to humans.

With big animals that live in fairly open environments, sometimes you just need to be far enough away. As an undergraduate I worked as a field assistant on a pronghorn project in Montana. We hiked up hillsides and watched for females to get their babies out of hiding to nurse. We used binoculars and spotting scopes so we could see well enough to note ear tag colors, yet distant enough to not make the animals feel threatened by our presence.

With the pocket mice, that are so small, quick and nocturnal, getting far away and sitting quietly doesn’t work very well. I spent a dozen or so nights trying, outfitted with a camp chair and night-vision goggles. I set out some seeds on a tray and hoped the pocket mice would come. With one exception, they did not. Those were some of the longest nights I have ever experienced, sitting in the dark, staring at nothing.


Andrea Sork, a field assistant, uses night vision goggles to observe a kangaroo rat. On the right is an infrared camcorder.

What ended up working was trapping them first and then putting the tiny rodents inside a clear arena with the seeds, so I could watch them through the sides. While it isn’t perfect—they spend time exploring the walls and digging to get out—it at least allowed me to see them! And most of the animals decided that the seeds inside the arena were worth taking; even though I was sitting 12 feet away, the mice made multiple trips to the seed pile and back to their burrow. It helped that I sat very still and quiet the whole time. But it was exciting watching the animals come and go!

In addition to physically watching the pocket mice, camera traps can be hugely important. You can set multiple cameras at once and leave them for many nights. Later, as you go through the photos and videos, you can see where the mice were and what they were doing—especially if you leave food trays or set them at burrow entrances or some other specific place. The upside is that you can have a lot more “eyes” out at once, and cameras are less intrusive than a person sitting there. The downside, though, is that you can’t be sure cameras are catching everything, and they often have a pretty narrow view.

If you get a chance to see some animals in the wild, take an extra moment to watch them do their thing. Normal activities like sleeping or eating are a feat to witness, and there is so much to learn just by sitting still and watching!

Rachel Chock is a graduate student and volunteer with San Diego Zoo Institute for Conservation Research’s Pacific pocket mouse project. Read her previous post, Protected Habitat in Southern California.




Although she occasionally ducks into the nest box area, Antiki now spends most of her time practicing her flying skills outside.

We have switched the camera view of the San Diego Zoo Safari Park’s Condor Cam. Our faithful viewers have been able to watch our California condor chick, Antiki, hatch and grow in her nest box, but now they can view her out in her flight pen with her parents, father Sisquoc and mother Shatash, because she’s taken the next exciting step in her development—Antiki has fledged!

Fledging is the process in which a young bird leaves the nest. We consider a California condor chick to be fledged when they can fly to the higher perches in the pen—approximately 10 feet off the ground. When condor chicks fledge, they tend to be around 140 or 150 days old. The youngest bird to fledge here at the Safari Park was 123 days old. Antiki flew for the first time at 156 days of age.

Our condor nest boxes are elevated; they’re on the second floor of the condor breeding facility. The nests have one entrance that leads to the roost area. The entrance has an 18-inch barrier at the base to prevent young hatchlings from wandering out of our camera’s view. This barrier also provides exercise for the chick when it is big enough to start jumping up onto the barrier. The roost area is open to the flight pen and has a ledge that is about eight feet off of the ground. There is a five-inch-diameter pole leaning from the ground to the ledge; we call this the “pole ladder.” The condors can walk up or down this pole ladder to get to or from the nest. They can, of course, fly to the nest as well if they desire.

For a few weeks, Antiki was able to walk down the pole ladder to start exploring the flight pen. She would watch Sisquoc and Shatash eat, sometimes begging for them to feed her, sometimes playing tug-of-war trying to take food from them. She also got to drink from the pool for the first time. She would climb up onto an eight-foot-tall stump perch and up into the olive tree in the pen. She started to spend the night out in the pen, perched up in the tree, under the watchful eyes of her parents.

We still had not seen her actually fly to any of the perches, though, until September 13. That morning, after being warmed by the sun, she took a short flight from the olive tree to join Sisquoc on one of the 10-foot-tall perches. After that, she could deftly fly from perch to perch like a pro! Since that morning, Antiki spends the majority of the time out in the pen, sometimes returning to sit in the shade of the roost.

When condor chicks fledge in the wild, it can be a long process as well. They will often walk around the mouth of their nest cave, hopping about, testing their wings. They may hop or climb into nearby shrubs or trees to get a better vantage point. Very seldom do chicks just spring forth from their nest into the wild blue yonder. They usually need to exercise and develop their abilities before embarking on such a dangerous venture. Mom and dad are always present to escort or protect the chicks. Parent condors can be very vigilant and defensive of their chicks. After all, much energy and many resources went into producing just this one chick, so they try very hard to ensure success for their only nestling. One pair of condors in California actually chased a black bear away from their nest!

With this new camera view, you’ll be able to see the roost area, most of the perches in the pen, the feeding area (shift pen), shade areas created by plants, and the pool. The view is wide, so detail is a bit harder to discern. Also, we do minimal maintenance in the pen, so the pen has lots of plant growth and dried food (animal carcasses) in it. We limit our activities in/near chick pens so as not to expose Antiki to humans, thus desensitizing her to our presence. We have found that chicks raised in isolation from humans tend to be more successful once they are released to the wild. The flight pen won’t look as nice as an exhibit you might see at the Safari Park or the Zoo, but Sisquoc and Shatash prefer it that way, if it means we stay away from their precious chick!

If, by chance, you don’t see Antiki out in the pen, she could be resting in the shade of the roost, or she may have hopped back into the nest box. This is completely normal. The adult condors do the same thing. Just give her a little time; she’ll come back out into view later. We have a great volunteer staff that moves the camera for the nest box view, but we keepers move the camera when it is the pen view. We’ll do our best to zoom in to give you a good view of her when we can, but we are not always near the camera controls as we are also taking care of the other condors.

So what’s next for Antiki? She’ll stay in the pen with her parents for a little while longer. She is still learning from them. In the wild, condor chicks stay with or around their parents for up to 18 months. We don’t let them stay that long here at the Park. If we did, the next breeding season would probably be compromised; the presence of the fledgling may prevent the parents from breeding the next year, or the parents may act aggressively towards the chick if they try to nest again. Sometime in this fall, Antiki will be removed from her parents, so they can prepare for the next breeding season. She will be introduced to other birds her age in a group with an adult bird that acts as a behavioral mentor. In the meantime, it will be decided whether she will be a candidate for release to the wild (and where) or held for the captive breeding program. I’ll keep you informed when this happens. Until then, please continue to keep checking in on our big girl.

Everyone’s interest and enthusiasm over the hatch and growth of Antiki have been wonderful. We really appreciate all of the comments and questions we have received throughout her development. Thanks again for all of your support—we couldn’t do it without you!

Ron Webb is a senior keeper at the San Diego Zoo Safari Park. Read his previous blog, One Step Closer to Fledging.


CSI: Coronado


Feathers from a California least tern mark the scene of the crime. (Photo by Maggie Lee Post, courtesy Naval Base Coronado)

I never expected to gain detective skills on the California least tern and western snowy plover project. As field biologists, our observation skills are critical in assessing nest success, chick survival, and other aspects of population ecology throughout the season. There are times when we walk up to a nest and something is amiss: the eggs are missing, an egg is punctured, or sometimes we find only pieces of broken egg shell in the nest cup. This is when we get to an interesting aspect of our job: ‘crime scene’ investigation! Many predators try to take advantage of the hundreds of eggs in a tern colony and those in plover nests. We partner up with predator biologists to help solve these cases of nest predation and prevent more from happening.


Can you make out the American crow tracks left at this crime scene? (Photo by Billy Smith, courtesy Naval Base Coronado)

Early in the season this year, when the first nests were being filled in the tern colony, the common raven and American crow (members of the Corvidae family) were the main threats. Clues left at the scene of the crime included tracks, pieces of egg shell, and sometimes even remnants of yolk in and around the nest cup. Once these clever birds figured out that we used small green sticks to mark each well-camouflaged nest, they found several other nests at one site. We quickly changed our marking tactics, and began using sea shells to mark nests.

In the middle of the season, when the tern chicks were reaching that stage when they were just beginning to fly, we saw an increase in predation by raptors. Peregrine falcons and great horned owls were linked to some of the crimes. These skilled hunters make swift kills but leave messy crime scenes containing tracks, feather piles, and sometimes leftover pieces of their prey.

Birds are not the only hunters in the area. Skunks and other small, opportunistic mammals use their keen senses to find and eat tern and plover eggs. Since most of these terrestrial creatures forage around dusk or at night, we are able to detect tracks and other signs during our morning patrol—and we definitely smelled a skunk’s presence at one of the beaches! Skunks are especially problematic because they are capable of digging under the exclosures we place over the plover nests to get to the eggs.

Predator management is no easy task, and the predator biologists do an excellent and professional job. They come up with inventive scare tactics and other methods to alleviate the pressure on our protected birds. Our partnership gives the terns and plovers a chance to incubate their eggs and raise their chicks in peace. This is why I’m out here using my detective skills to help the terns and plovers nest successfully on the beaches of Coronado. Case closed.

Melissa Murillo is a research associate at the San Diego Zoo Institute for Conservation Research.


How and Why We Came to Sequence Northern White Rhino Genomes

What is astounding, and hopeful, is that the frozen cell cultures banked in the Frozen Zoo® represent a significant sampling of the genetic diversity of northern white rhinos and a potential means for preventing extinction of this form of rhino. From our first northern white rhino cell culture established over 35 years ago, through the last northern white rhino calf, born in 2000 and added to the Frozen Zoo in December 2009, there is more of the gene pool of these rhinos in the Frozen Zoo than survives in the living animals. Given the dire situation, we are driven to accept that the only way to prevent the loss of the northern white rhino will necessarily involve the resources of the Frozen Zoo.

How and Why We Came to Sequence Northern White Rhino Genomes by Oliver Ryder, Ph.D., Director of Genetics

Genetic material from 12 northern white rhinos is banked in the Frozen Zoo.

It is a long and improbable road that brought the last female northern white rhino in the Western Hemisphere, Nola, from the grassy swamps of the headwaters of the Nile, via the Khartoum Zoo and Eastern Bohemia Zoo in Czechoslovakia to the San Diego Zoo Safari Park, where I recently was able to watch and listen to her eat her breakfast. The satisfying sound of her chewing is a sound that, like the species itself, faces extinction, I reflected. Perhaps even more improbable is that her frozen cells will contribute to rescuing the northern white rhino from extinction. Yet, we are resolute to try.

How and Why We Came to Sequence Northern White Rhino Genomes by Oliver Ryder, Ph.D., Director of Genetics

Nola is the last northern white rhino in North America.

Since the first moment I learned about the existence of the northern white rhino, the question of their difference from the now more numerous southern white rhino was at the forefront. Legendary South African conservationist Ian Player, the man who led the effort to bring southern white rhinos back from a small and vulnerable population that was reduced in number to less than 100 to, now, the most numerous form of rhinoceros, posed the question the first time we met. It was another legendary individual, Dr. Kurt Benirschke, the founder of the conservation research effort at the San Diego Zoo, who had brought us together. With Dr. Benirschke’s support, a postdoctoral scientist, Matthew George Jr., conducted the first genetic studies comparing northern and southern white rhinos and published the findings in 1986. Since his initial studies, our own efforts and those of other investigators have added to our initial findings. All the studies provide evidence that the two forms are genetically diverged, but the methods used over the years have now been superseded by advances in genome sequencing that have taken place over the last decade.

How and Why We Came to Sequence Northern White Rhino Genomes by Oliver Ryder, Ph.D., Director of Genetics

Dr. Oliver Ryder holds a tissue sample from the Frozen Zoo.

Comparison of the sequenced genomes of northern white rhinos with southern white rhinos will provide an objective assessment of the divergence of the genomes of the two rhino forms. This “crash” of data will shed light on the question of whether they are sufficiently divergent to be considered species or subspecies. Whatever the revelation on this matter, it will be overshadowed by the detailed knowledge of the DNA sequences encoding their behavioral and ecological adaptations that have evolved since their divergence from a common ancestor, and the time frame over which these changes took place. The ability to resolve these and other questions is a hallmark of the entry into the era of genomic biology, and serves as an example of how this emerging science can contribute to conservation of biological diversity. Knowledge of the northern white rhino genome and its expression will, as we strive to turn the cells of northern white rhinos in the Frozen Zoo into young rhinos, serve as roadmaps for our efforts.

Oliver Ryder is director of the Genetics Division at the San Diego Zoo Institute for Conservation Research.


Celebrating 40 Years of Leadership


We’re celebrating our success using science to help save species. (Pictured: Bai Yun with Su Lin,  her third cub.)

It was overwhelming, inspiring, and at times emotional. A group of conservationists gathered at the Beckman Center Thursday, September 10 and heard from leaders in wildlife conservation, who took the podium and described their life’s work to the crowd. The theme of every talk was doing the “new,” the perceived “impossible,” to save species.

It has been 40 years since Kurt Benirschke, M.D. began the conservation science department of San Diego Zoo Global, which developed into today’s San Diego Zoo Institute for Conservation Research. Today, conservation researchers met to celebrate this milestone by sharing their work and their plans for the future.

Each speaker had a story to tell of challenges, tears, and success. Mike Wallace spoke about condors, about protesters demanding that we let them “die with dignity,” about administrators fighting for the right to save this iconic bird species, and then about finally seeing condors flying free again in the wild—a recovered species that still needs human management and protection. Don Lindburg, Ph.D. spoke about the challenge of getting pandas, the skepticism of those who did not believe we could work successfully with pandas, and the joy of the first baby panda birth. And, of course, Barbara Durrant, Ph.D. and Oliver Ryder, Ph.D. reviewed the work they have done with assisted reproduction, with the Frozen Zoo®, building hope for the future without knowing for sure what we would need—and now that work is needed so much to save a species on the brink: the northern white rhino.

It was a celebration of 40 years of history, of leadership, of going down the road less traveled (and, really, a road that everyone said couldn’t be traveled) to make a difference for the future. And it was such an honor to be here.

Christina Simmons is the public relations manager for San Diego Zoo Global.


Extreme Volunteerism: Bighorn Sheep Count 2015


We watched for bighorn sheep—and this ewe watched us!

We were up before the sun in an effort to beat the heat. July temperatures in Anza Borrego Desert State Park can soar up to around 120 degrees Fahrenheit. We had a little more than an hour’s hike ahead of us from our campsite to our count site in Cougar Canyon. Once we loaded our packs with enough water and supplies to carry us through the day, we were on the trail.

You might be wondering who would be crazy enough to willingly go desert backpacking during the hottest part of the summer. Those were my thoughts, before I became part of this brigade of citizen scientists who volunteer Fourth of July weekend every year to do just that. Our all-girl squad of mammal keepers from the Safari Park (Charlie Hyde, Mandi Makie, and myself) has been “counting sheep” for the past several years at this site. The Safari Park’s mammal department includes another team of counters who have been involved with the program for over 20 years—Gloria Kendall, Eileen Neff, and Michelle Gaffney are seasoned professionals when it comes to spotting sheep!


Bighorn sheep live in harsh, rugged terrain.

All of this hard work is an effort to conduct a census on the bighorn sheep population within Anza Borrego Desert State Park. These animal counts are critical in determining how effective recovery efforts are for this species.

With the count in its 45th year, the general trend has been an increase in the number of bighorn within the Peninsular Range. At one time numbers were as low as 400 animals. Although their population has climbed to around 955 animals at best, they are still extremely vulnerable due to habitat loss and fragmentation and disease from livestock.

While bighorn sheep can be seen year-round in the park, we get our most accurate counts from early to mid-summer. Not only does the hot weather drive the sheep down towards their watering holes, where volunteers are stationed nearby to count and identify the animals, but also enough time has elapsed since the lambing season that neonate mortality rates will not skew our numbers. This gives researchers the most realistic snapshot of the current bighorn sheep population in the park.


We nicknamed this young male “Blondie,” and his female companion “Dark Ewe.”

Once the team has safely reached the observation site, we sit quietly for the next 10 hours scanning the hillsides for any sign of movement. After nearly an hour, Charlie signaled that she’d spotted sheep. We all looked directly across the canyon where two individuals, an ewe and a young ram, had been sitting in the shade watching us the entire time. Clearly unfazed, they continued to rest for several hours before moving down the hillside. We saw this pair, nicknamed “Blondie” and “the Dark Ewe,” several times over the next three days.

In years past, our team has been lucky enough to encounter a desert tortoise each time we’ve camped near Cougar Canyon.  As we hiked out on our last day in the park, I worried that we wouldn’t encounter this elusive animal. When the air temperature and the sand heat up, these reptiles hunker down in their burrows to stay cool, not emerging until early evening. We were running out of time.


Bonus sighting: a big, beautiful desert tortoise!

Once we reached the last stretch of trail before our ascent into another canyon, I glanced to my right and spotted a large moving rock. Staring back at me was a big, beautiful desert tortoise! Unable to believe my eyes, I excitedly called to Mandi and Charlie to check it out. The tortoise had no obvious markings on it to suggest that it was an animal researchers were monitoring. It’s good to know that there is a tiny group of tortoises flourishing on their own in this inhospitable habitat. After we gave this little guy (or gal) a good once over so that we could share details of our encounter with park rangers, we were back on our sheep finding expedition.

Hours passed in the blistering heat on our final count day, and there were no sheep to be found. What a way to end our trip! We packed up and made our way back to camp, checking for tortoise burrows along the way, when a flash of movement caught my eye. Gracefully running across the valley wash was a herd of 11 bighorn sheep! Many of the individuals we had counted and nicknamed were in the group. There was “Dark Chocolate,” a beautiful ram who was over 11 years old; “Old Girl” and her two lady friends; as well as some other young males who were new to us. Altogether, we spotted 18 different bighorn sheep over the four-day weekend—a new best for our team.

With that incredible experience fresh in our minds, we ended our outdoor endurance test and headed back to the ranger station to tally the sheep numbers from all of the teams.

The overall total from all count sites was 253 bighorn sheep. This number fell short of what we’ve seen in the past few years, but it may be due to lack of volunteer sheep counters; not all observation areas were staffed.

Special thanks to the San Diego Zoo Safari Park Mammal Department for the support they offered this keeper team on our latest field excursion.

Amanda Lussier is a keeper at the San Diego Zoo Safari Park. Read her previous blog, Party Time: Leroy the Giraffe Turns One!


One Step Closer To Fledging

Antiki has moved out of the nest box, spending her time on the ledge outside where her parents groom and feed her.

Antiki has moved out of the nest box and is spending her days on the ledge outside where her parents groom and feed her.

As many Condor Cam viewers have experienced, the rearing process for a California condor can be long and slow. It makes sense, though, for a condor to develop so slowly. She has lots of growing to do. When our chick, Antiki, hatched, she weighed approximately 6.35 ounces (180 grams). When she reaches her fledge weight of 17 pounds (8 kilograms) or more, she will have increased her hatch weight by 44 times! I, myself, have only increased my birth weight by 19 times.

On August 6, at 118 days of age, Antiki took her most recent step toward leaving the nest: she jumped up onto the barrier between her nest box and the adjoining roost area. She later hopped back into her nest, but that’s OK. There’s no hurry to fledge, or leave the nest, just yet. Her feathers still need time to fill in all of the way. In the meantime, hopping up and down from the barrier will exercise her muscles, as well as improve her balance. On August 11, she hopped into the roost area on the other side of the barrier for the first time. Here, she can warm herself in the sun, if she so chooses. While out in the roost, she can also rest or sleep in the shade, perch with her parents (if they are not perched out in the flight pen), or step out to the roost ledge to soak up the sun’s rays for the first time. The ledge is about 8 feet from the ground – high enough to make the parents feel comfortable and secure in their nest, but not as high as a condor nest in the wild. Antiki may get near the edge, but she will be cautious in doing so, so she doesn’t teeter off. It is natural for condor chicks to explore and exercise on the edge of their nest cavities. Rarely do they fall out; in 33 years of raising California condors here at the San Diego Zoo Safari Park, we have never seen a chick fall from its nest area prematurely.

The next step of Antiki’s development will be to fledge. When she is ready, she will jump off of the 8-foot-high nest ledge. She will either slow her fall to the ground below the ledge, or fly to a nearby perch. We consider her fledged when she can get up on a perch by herself. The youngest we have seen a condor chick fledge here at the San Diego Zoo Safari Park is 123 days old. Sometimes chicks have waited until over 165 days. It all depends on the chick.

The parents tend to be very vigilant at this phase of their chick’s development. It might appear over-protective to us, but keep in mind that they have invested an entire breeding season and lots of energy into this one chick. It benefits them greatly to make sure that their sole offspring is safe, healthy, and strong. They usually don’t coax or pressure their chick to leave the nest; on the contrary, we have seen parents make sure that it doesn’t stray too far from the nest if it’s not ready yet. The parents will usually perch and/or roost near the fledgling. They also will join her when she finally starts going to the feeding area of the flight pen. Most of the time, though, they will push her aside and they will eat first, feeding her when they are done. In “condor culture,” the bigger, more dominant birds usually eat first, while the subordinate birds wait their turn. The earlier Antiki learns this from her parents, the better she will assimilate into a wild population after she is released. Don’t worry—Sisquoc and Shatash won’t let Antiki starve. They will continue to feed her even when she is out in the flight pen. Eventually, she will eat more and more on her own.

Depending on Antiki’s development and activity levels, we will try to switch the Condor Cam view from the nest box/roost area to the flight pen. You’ll be able to see the roost area, most of the perches in the pen, the feeding area, shade areas created by plants, and the pool, where she can either drink on her own or bathe (one of my favorite condor activities to observe!). The view will be wide, so detail will be harder to discern. Also, we do minimal maintenance in the pen once the chick is large enough to look over the nest box barrier and into the pen. So the pen has lots of plant growth and dried food (animal carcasses) in it. We limit our activities in/near chick pens so as not to expose the chick to humans, thus desensitizing her to our presence. We have found that chicks raised in isolation from humans tend to be more successful once they are released to the wild. The flight pen won’t look as nice as an exhibit you might see at the Zoo or the Safari Park, but Sisquoc and Shatash prefer it that way, if it means we stay away from their precious chick!

Thanks so much to all of our faithful and dedicated Condor Cam viewers. Soon, your support and devotion will be rewarded when our “little big girl” spreads her wings and takes that next step. Rest assured, though, that Antiki’s story will be far from over!

Ron Webb is a senior keeper at the San Diego Zoo Safari Park. Read his previous blog, Condor Chick: Getting Big!


Learning What We Can Learn From Camera Trap Photos: Part 2


Can an Andean bear’s nose be a way to determine its age?.

I recently wrote about how we’ve determined that, with caution, researchers can identify individual Andean bears in camera trap photos. Researchers should therefore be able to answer some basic questions that have big implications for Andean bear conservation. However, there are many other important questions for which we still don’t have answers. For example, does the population in this watershed have an age structure that will be stable over the long-term?

How do you figure out how old an animal is when it was born in the wild years ago – 2 years ago, 8 years ago, or 14 years ago? Field researchers often use characteristics of mammals’ teeth to estimate their ages, but those methods require capturing the animals and it is definitely not easy to capture Andean bears. It turns out that we can use camera traps.

I might not have seriously considered using camera trap photos to investigate these kinds of questions except for a conversation with a field researcher from our collaborator, the Spectacled Bear Conservation Society. When I showed him a photo of an Andean bear living at the San Diego Zoo, he said “Wow, that’s an old bear!” He was correct, but how did he know that? He couldn’t describe exactly what it was about the photo that suggested that the bear was old, but I remembered that several years earlier some researchers had documented that the nose color of African lions changes as they age. Might the same thing happen in Andean bears?

Using photos of known-age bears from various zoos, we’ve determined that although the changes in nose color aren’t as predictable as we’d like, they’re consistent enough to provide some information about the age of the individual bear. And, using photos of captive- and wild-born cubs, we’ve verified that it’s possible to estimate the ages of young cubs from camera trap photos. Since fewer than a dozen Andean bear birth dens have ever been found in the wild, this could be really helpful in determining when female bears give birth to cubs. That information, in turn, is the first step in determining why females give birth then, and not at other times of the year.


Notice the changes in Tommy’s nose from when he was  (left to right) 2, 17, and 23 years old.

Another set of conservation research questions can only be answered with information on the genetic structure of a population, or information on how individuals are related to one another. Does the population in this mountain range have a functional connection to other populations or is it isolated and inbred? What traits affect the probability that a female, or male, will have surviving offspring? Who knows which cub was sired by which male? Do cubs look like their parents? In other words, do the facial markings of cubs look like the facial markings of their parents? The only Andean bears with known mothers and fathers are the cubs born in captivity, so I worked with collaborators to test whether the markings of related captive-born Andean bears looked more similar than the markings of unrelated captive-bear Andean bears. They don’t. Sometimes bears that are closely related look alike, but sometimes they don’t. On the other hand, sometimes bears that look alike are closely related, but sometimes they’re not related at all. So, although it might be tempting to say that a cub which looks like an adult male is the offspring of that male, that’s a potentially misleading conclusion. We’ll just have to wait for the development of good genetic tools before we can answer questions about the genetics or kinship structure of Andean bear populations.

After thorough review and discussion by other scientists, this work has been published online in PeerJ, where you can read the details and see more photos.

Russ Van Horn is a scientist at the San Diego Zoo Institute for Conservation Research. Read his previous blog, Learning What We Can Learn from Camera Trap Photos: Part 1.


Terns, Plovers, and People: Living in Harmony


This beach on Naval Base Coronado is one site where field biologists are studying California least tern and snowy plover populations (U.S. Navy photo by S. McLaughlin, SDZG)

As field biologists, we are lucky to have some of the most beautiful offices in the world. Every day, my coworkers and I get to enjoy long walks on the beach, warm sunshine and the occasional passing dolphin pod. Of course with views like the one in the photo, we are working alongside many other people enjoying a day at the Pacific Ocean. It’s wonderful to see people appreciating the beach habitat we all love so much, especially when it’s done in a respectful and responsible way. So, here are a couple of thoughts from a field biologist.

Both the California least tern and western snowy plover are sensitive to human disturbance. While some bird species will remain on their nest until you are very nearly upon it, terns and plovers seem to hop off at the first sign of danger. Plovers can be seen in the vicinity of the nest, performing the broken-wing display to draw perceived predators away from their nest. Terns take a more aggressive approach, screeching at and dive-bombing anyone that approaches their nest; sometimes several members of the colony will join in to drive the threat away. With the numbers of terns and plovers at critically low levels, it’s important that the birds are able to spend their energy caring for their young, instead of chasing off disturbances.


With chicks this cute and helpless, it’s easy to see why we want to protect California least tern populations. (U.S. Navy photo by S. McLaughlin, SDZG)

The most common instances of disturbance we see out in the field are people walking through the colony and dogs being allowed off leash in areas with nesting birds. In addition to upsetting the adult birds, these types of disturbances can result in trampled eggs and chicks, and stressed-out young. Luckily for all the recreational beach users out there, avoiding creating a disturbance is very easy! The most important step to take is observing and abiding by posted signs. If you are ever approached by a game warden or field biologist, don’t be afraid to ask questions. We love to talk about the terns and plovers, and outreach is an important part of our jobs!

The beaches of southern California and the birds that live there offer amazing opportunities for people to engage with nature. If we enjoy these resources respectfully and responsibly they will hopefully be here for many more years to come.


Stephanie McLaughlin is a research associate at the San Diego Zoo Institute for Conservation Research.


Learning What We Can Learn from Camera Trap Photos: Part 1


Andean bears are sometimes called spectacled bears because of the rings of lighter colored fur around their eyes.

Others have said it before and it’s true: New forms of technology such as camera traps make it possible for field researchers to collect information we could previously only dream about. Technology advances so quickly that we’re still evaluating what we can do with these tools and what questions we can and cannot answer by using them. We have many basic questions that are still unanswered even for species as large as the Andean bear. Here are two of the most basic: How many are there? Are the populations increasing, stable, or decreasing? The answers to these questions and others would help researchers, conservationists, and governments decide how much of their limited resources to invest in research efforts and conservation actions, in the hopes that 100 years from now there will still be bears roaming the forests of South America. Unfortunately, there are still no answers to these questions.

How would you answer these questions? How do you count animals that live in dense forests in rugged habitat, when those animals avoid contact with humans? It’s been said for decades that the markings of individual Andean bears vary so much that you can identify each individual bear just by looking at it. If that’s true, then maybe we could use camera traps to identify individual Andean bears in photographs and then estimate population sizes and densities. However, how do you test whether individual bears can be reliably identified in photographs? In order to test this you’d need photos of a lot of different bears whose identity you definitely knew. That means you can’t just use photos of wild bears from camera traps, because you don’t know how many bears walked in front of the camera traps.


Compare the markings of this bear, Tommy, with the bear above (named Turbo) and notice the differences.

The only way we could think of to test this was to take photos of different bears from captivity, so we’d know the identify of the bears, ask people to compare those photos, and keep score of whether bears were correctly identified, or not. When a group of international collaborators and I did this we were surprised to discover that people were initially not very good at this task. In fact, they would have done just as well if they’d flipped a coin! That’s really not the kind of result we were expecting, or hoping, and it led us to consider whether we were over-confident in our own abilities to identify individual bears. However, it turns out that with a little practice and training, participants became better at identifying bears from their photographs. After thorough review and discussion by other scientists, this work has been published in the journal Wildlife Biology and you can read all the details and see more photos here.

So, the good news is that, if we’re careful, we and other field researchers can use photos from camera traps to identify individual Andean bears, estimate the sizes of their populations, and compare populations densities. Now, we “just” need to get the cameras into the forests where there are bears!

Russ Van Horn is a scientist at the San Diego Zoo Institute for Conservation Research. Read his previous blog, Ambassador Mi Ton Teiow Receives a New Posting.