Institute for Conservation Research


Birds of the Past Reveal Genetic Secrets

Paquita examines samples of archived bird specimens.

Paquita examines samples of archived bird specimens.

The smell in the collections room immediately brings back very good memories. When I first visited the California Academy of Sciences in 2007, their collection was temporarily housed in a different facility. Now I am standing in a room of a spectacular modern building in Golden Gate Park, San Francisco. The location may be different, but the smell hasn’t changed. Ten thousands of bird and mammal specimens from all over the world are stored here.

My mission is also almost the same. I am here for the Galápagos mockingbirds, the birds that have been the center of my scientific interest for many years now. Moe Flannery, the collections manager, guides us through the narrow hallway lined with massive cabinets. I am accompanied by my friend and colleague Tandora Grant. We need to find a very specific drawer, one that carries the tag ‘Mimus parvulus’ and contains the specimens of the two Galápagos mockingbird subspecies ‘wenmani’ and ‘hulli’. Moe successfully locates a few ‘Mimus parvulus’ drawers, but as we look through the nametags of the specimens inside, we read ‘personatus’, ‘barringtoni’, ‘bauri’… Not the right ones. I am still delighted by their sight; it feels a little bit like seeing old friends.

When I came here in 2007 as a Ph.D. student, I spent a few days with these birds, working on 349 of them. Some of them look different from each other. Millennia of living on isolated islands have shaped these birds into different species and subspecies – like the Darwin’s finches that have become a textbook example in evolutionary biology. But it was actually the mockingbirds’ distinct look on different islands that gave Charles Darwin his first vital clue for his theory of speciation under natural selection.

Tandora helps sleuth out  genetic mysteries of the birds of the Galapagos.

Tandora helps sleuth out genetic mysteries of the birds of the Galapagos.

The birds we are looking at, lined up side-by-side, belly-up and legs crossed, are all well over 100 years old. The nametag on their legs specifies their origin and species’ name. Because the taxonomic knowledge has changed since their collection, many actually carry two or three tags with updated information. We can’t see ‘hulli’ or ‘wenmani’ anywhere. “Every once in a while we get unlucky,” Moe says before she takes off to get a tall ladder on wheels that resembles a portable staircase. She climbs to the very top and pulls out the top drawer. Back down on safe ground she asks, “Is Culpepper what you’re looking for?” I feel immediately embarrassed—I’ve forgotten the islands’ old names! Like the birds, the islands were renamed several times over the last century. Tandora grabs her iPhone and Google’s Culpepper. Yes, it is Darwin Island, and birds from Wenman, now called Wolf Island, lie in the same drawer. We found what we came for!

Darwin and Wolf islands are the most remote of the Galápagos Islands, separated from the rest of the archipelago by a stretch of almost 100 miles of open ocean. For a somewhat flight-lazy bird, like the mockingbirds, such vast open water with no other islands in sight is probably quite an effective deterrent to emigration. That’s at least my hypothesis and the reason why these specimens, now neatly placed in front of us, are of so much interest to me.

Galapagos mockingbird species from 100 years ago awaiting sampling.

Galapagos mockingbird species from 100 years ago awaiting sampling.

I’ve studied these birds for many years now. I spent many months in the Galápagos and visited almost all islands to collect blood samples from the different mockingbird species and populations. A little drop of blood from a couple of dozen birds from each island was all I needed to let them tell me about their interisland traveling habits. The birds’ genetic information gave me insights into their population sizes and their relationship between different islands. The analysis of the historic specimens that I sampled at the Academy in 2007 added an interesting timely perspective; it revealed which island populations have changed the most over the last century.

I take out my sample collection material. These specimens from Darwin and Wolf escaped my scalpel blade last time. At the time, it was uncertain whether I would be able to obtain contemporary samples of their subspecies. Now their time has come. I pick up the first specimen and cut a tiny piece of tissue sample from one of the toe pads. One specimen down! The spot on the foot where the sample was taken is barely visible. Minimal damage to the specimen, but lots of new information to be gained.

The historic samples we’ve just collected are the first step in the discovery of the genetic secrets of these two remote populations. Together with collaborators, I am planning to climb onto Darwin and Wolf islands early next year to collect blood samples from living birds. The islands are infamous for their inaccessibility, but we’ll have an excellent team at hand. Let the adventure begin!

By Paquita Hoeck, Ph.D., San Diego Zoo Institute for Conservation Research.


A Trip Down Memory Lane

Rebecca tells students about the work she does helping endangered Hawaiian birds.

Rebecca tells students about the work she does helping endangered Hawaiian birds.

While it has been a long time since I stepped into a classroom, the second I walked onto Pahala Elementary School’s campus a flood of memories of my own school days came rushing back. I remember coming into the first class of the day and still wanting time to chat with my friends. I remember the small tables and chairs that I know I used to fit into, though now it’s difficult to imagine. And while I remember the class bells ringing in school, yesterday I was very nearly shocked out of my skin when the bell signaled the start of class. I guess that’s the sort of thing you never notice as a kid.

That morning I had the pleasure of assisting Robin Keith, a member of the Conservation Education Division at the San Diego Zoo Institute for Conservation Research, in administering an essay contest to the sixth- and seventh-grade classes of Pahala Elementary and Ka‘u High School in Pahala, Hawaii. This essay contest was designed to discover a student’s own interpretation of, and experiences with, wildlife. The information will help guide our conservation education and outreach programs in support of our Hawaii Endangered Bird Conservation Program. Some students struggled at the beginning, not really sure what to write about, but in the end they all submitted great stories. Two winners will be chosen at random, and that student will be taking his or her entire class on a field trip to the ‘Imiloa Astronomy Center of Hawaii.

Students work on their wildlife conservation essays.

Students work on their wildlife conservation essays.

After the essay portion of the class, Robin spoke about current conservation issues facing Hawaii and about techniques used at the Keauhou Bird Conservation Center (KBCC) for saving native Hawaiian birds. Then it was my turn to field any questions that the students had about KBCC. I have spent the past six years working with some of the most endangered and difficult-to-rear bird species in Hawaii, but when it came to commanding the attention of 12 and 13 year olds, I was a bit daunted. Usually, when I’m presenting information about my job, I’m in my workplace with every conceivable prop and medium available to showcase the native birds. Here, however, I was standing at the front of the classroom with nothing but my strong voice, great bird conservation information, a smile, and enthusiasm for my job! In the end, I hope the students walked away with a great writing exercise and some valuable information about Hawaiian bird conservation. I walked away from the campus hoping that I had planted at least one seed of love and respect for native Hawaiian wildlife.

I must send out a very big mahalo (thank you, in Hawaiian) to the teachers of Pahala Elementary and Ka‘u High School for allowing Robin and me to invade their classes and for their enthusiasm in teaching their students environmental education. Another very big mahalo to the wonderful students, who had excellent questions about the birds and embraced the essay-writing challenge. We look forward to future collaborations with students and teachers on the Big Island as we work to foster pride and support for conservation of Hawaii’s natural heritage.

Rebecca Espinoza is a research associate at the San Diego Zoo’s Keauhou Bird Conservation Center.


Biomimicry, Biomaterials, Biomimetics

Our armadillo demonstrates the use of keratin, the wonder protein.

On Wednesday, September 28, the San Diego Zoo hosted the second in our series of fall Biomimicry Receptions. This special evening, sponsored by the City of Murrieta, welcomed David Kisailus, Ph.D., and several of his students from the University of California, Riverside, who work on biomaterials and biomimetics. Guests were treated to an after-hours walk through the Zoo to the Treetops meeting room, where wine and appetizers were served while guests mingled with each other and got to know to UC Riverside students. The students gave us some insight into their research through posters and biological artifacts from the animals they work with, such as abalones and marine snails.

Photo credit: Shadow Van Houten

The theme of this evening’s animal presentation was keratin, the wonder protein used to make everything from armadillo scales to rhino horns to human hair. Even though our armadillo ambassador was a bit shy that night and stayed rolled up in a ball, he still had a lot to tell us about the inspiring adaptations found in nature.

Next, City of Murrieta Councilmember Rick Gibbs shared with us all the benefits Murrieta has to offer. All over California there are designated Innovation Hubs or iHubs. Governor Arnold Schwarzenegger spearheaded this initiative in March 2010, and in August 2011 the San Diego iHub was expanded to include Temecula, Murrieta, and part of Riverside. We were excited to have this opportunity to visit with Murrieta and spread the word of biomimicry throughout the range of the Innovation Hub.

Photo credit: Shadow Van Houten

The keynote speaker of the evening, Dr. Kisailus, then shared with guests his exciting research in biomimetics. In his lab at UC Riverside they research the question, “What can biology teach us about the synthesis of new materials?” Current engineering processes tend toward the use of unnaturally high temperatures and environmentally unfriendly methods. Dr. Kisailus is trying to amend these practices by studying the processes that occur in nature. Structures are created at ambient temperatures with available materials and biodegrade at the end of their lifetime. Perhaps even more amazing is that these structures often perform better than our human-engineered products. Abalone shells, enamel, and chiton teeth are among the most abrasion-resistant materials, ranking significantly higher than most human-made metal alloys.

Don’t miss the final reception of the series! We are changing up the location and on Thursday, October 27, we’ll be at the Arnold and Mabel Beckman Center for Conservation Research, on the grounds of the San Diego Zoo Safari Park. This LEED-certified building houses the San Diego Zoo Institute for Conservation Research, the largest zoo-based research effort in the world. This reception will feature Richard Lieber, Ph.D., of University of California, San Diego, who will be speaking to his experience linking animal biomechanics to orthopedic surgery. Please visit our Biomimicry website for more information and to register.

Dena Emmerson is a biomimicry research assistant at the San Diego Zoo. Read her previous post, The Da Vinci Index.


Save the Bear

A sun bear displays her impressive tongue.

May 16 to 22, 2011, is Bear Awareness Week, and we hope you’ll join us in celebrating these amazing animals. While you learn more about bears, please take the time to reflect upon the challenges all bears face in wild and learn all that you can about what you can do to make a difference to help conserve bears. At the San Diego Zoo, we are passionate about bear conservation, and we’re excited to share with you our current research efforts, as well as an overview of the challenges that free-ranging populations of bears face around the world.

The bear family (Ursidae) currently consists of eight species, seven of which are conservation-dependent species (the sole exception:  the American black bear). Each conservation-dependent species inhabits a very different habitat, has generally evolved to exploit a particular resource niche (which may change seasonally), and has evolved a number of striking adaptations that have enabled them to take advantage of the unique foods they eat and the habitats in which they live.

While each bear species has evolved, over thousands of years, to cope with the various natural challenges to survival found in their environment, they all face extreme challenges to their persistence in the wild due to the impacts of human populations and the rapid pace of environmental change due to human activities. While humans impact the environment in a variety of ways, ultimately it is one single factor that poses, by far, the greatest threat to the persistence of all wild bear populations: HABITAT LOSS. From great polar bears roaming the vast Arctic sea ice to diminutive sun bears dwelling in the tropical rain forests of Southeast Asia, suitable habitat is being lost or fragmented at an alarming pace. Climate change, resource extraction, and human population growth have all contributed to habitat losses. But, while these challenges may seem daunting, the reality is that if we can change our habits, reduce our carbon footprint, and make conscientious changes in how we buy and use products, we can reverse these trends, and we can save the world’s bears.

Historically, hunting was the greatest threat to all bear species. Unregulated hunting had dramatic impacts on population numbers for bears worldwide, especially in the first half of the 20th century, when a lack of regulation was coupled with enhanced access to bears (through motorized vehicles) and more efficient weapons. In the 1970s, the impact of hunting on some species, such as the polar bear, impelled wildlife biologists and managers to develop science-based harvest quotas that, over the years, served to stabilize polar bear populations. However, the unregulated “take” of wild bears continues in some parts of the world, and bear parts and the pet trade have continued to take their toll on a number of Asian bear species (except the giant panda).

Just as the impact of hunting on most bear populations was minimized through the efforts of people, so, too, can the impacts of habitat loss and climate change be reduced. We can all make a difference, and the first step is to get passionate about bears and bear conservation. A great place to start? The San Diego Zoo!

Come visit Kalluk, Chinook, and Tatqiq (polar bears); Montana, Scout, and Blackie (brown bears); Marcella and Francis (sun bears); Bai Yun, Gao Gao, and Yun Zi (giant pandas); Houdini and Tommy (Andean bears); and Ken and Bhutan (sloth bears). They are all great bear ambassadors. After visiting the wide array of bears at the San Diego Zoo, I have no doubt you’ll be inspired to turn off your TV, ride your bike (or walk) instead of driving, and carefully read product labels!

Find out more about the bear research the San Diego Zoo is actively engaged in…

Megan Owen is a conservation program specialist at the San Diego Zoo Institute for Conservation Research. Read her previous post, Love is in the Air.


Andean Bears: 30 Years Later

A young Andean bear is high in a tree next to a cornfield.

I’ve discovered that Peru is actually a lot smaller than you’d think. Sure, it may be around 2,000 miles long from north to south, and more than 550 miles wide from east to west, but it is still smaller than you’d think. Then again, so is the world itself.

One of the first people to conduct scientific research on Andean (spectacled) bears was Dr. Bernard Peyton, who worked in the field in Peru from the 1970s until just a few years ago. He was by far the most prolific scientist to write about Andean bears, in English and Spanish, and I have great respect for what he was able to accomplish. Due to technological advances such as remote cameras and GPS satellite telemetry, we are now able to address questions that he could only dream of, but a lot of his observations and hypotheses will undoubtedly stand up to all of our data.

It was a few years ago when I first read Dr. Peyton’s 1980 paper on Andean bears in Peru, and I didn’t take notes on all the specific locations he mentioned, especially when he referred to small villages in remote areas. I was more interested in general concepts and the biology of the bear than I was in the geography of Peru. Recently, however, I read that paper again, and I ran across a description that sounded surprisingly familiar.

On July 12 and 13, 1979, at 2,100 meters in elevation, Dr. Peyton saw a Andean bear feeding on corn in a communal cornfield owned by the villages of Queros, Quico Grande, and Hapu. On June 7, 2009, when the corn was about a month from being ripe, a colleague and I saw a bear feeding in the Q’ero communal cornfields, at an elevation of 2,300 meters. The three largest villages nearby were Q’ero/Quero Totorani, Quico Grande, and Japu/Hapu. Based on those unique place names, and the topography of the area, I have no doubt that when we saw the bear in the cornfield we were no more than five miles away, and possibly only ¼ mile away, from where Dr. Peyton saw a bear in the cornfield almost exactly 30 years earlier.

At times it is easy for me to become disheartened when I think about all the challenges to the conservation of species. From time to time, however, I’m reminded that all is not lost. Andean bears have been raiding the cornfields of local people for generations, causing them great economic losses. In spite of this, because the local people value their traditional lifestyle and wish to preserve the forest as it is, the bears are still there. I hope that in another 30 years we will have found a way to mitigate the economic damage caused by the bears, and both the people and the wildlife will still be there.

Russ Van Horn is a senior researcher for the San Diego Zoo Institute for Conservation Research. Read his previous post, Helping Bears in Machu Picchu.


First Steps for Francis

Will Marcella (pictured) welcome Francis?

This week we welcomed a new animal to the San Diego Zoo’s Asian Passage. Francis, the sun bear recently arrived from the Woodland Park Zoo in Seattle (see post Sun Bear Travels), exited quarantine and was introduced to his new permanent living quarters in Sun Bear Forest. His arrival heralded an opportunity for us to collect more data for our bear translocation study, first begun in 2008 with sloth bears (see post Ken: Sloth Bear Extraordinaire).

Our translocation study aims to determine if it is possible to reduce the stress associated with moving a bear into a new space. Such a transition can be a daunting experience for an animal, as it exposes them to a new environment with unfamiliar sights, sounds, and scents. We hope to discover if we can mitigate the bear’s natural anxiety by depositing its own scent in places around the exhibit.

To perform the study this week, we had staff collect fecal piles from Francis while he was in quarantine. Care was taken to ensure collection occurred at times when he was calm for an extended period, so the fecal samples did not contain the residue of stress hormones. On the morning he was released to his new exhibit, we achieved an “air of familiarity” in certain areas of the space by placing fecal piles in those areas. After he was released to the exhibit, we looked to see if he spent more time in pre-marked areas than unmarked ones and if his behavior was different between the two areas.

Francis experienced his first day on exhibit on May 3. Although he displayed a healthy sense of caution, he did fully explore the whole exhibit, ate his kibble and vegetables on exhibit, and even spent a little time resting in his new climbing structure. It was interesting to watch him explore the water features: he was initially nervous about the waterfall, but clearly curious. He returned to the falls several times throughout the day, and eventually he walked right through them. With persistence, he tackled that challenge.

It’s too early to tell you what the results of the study might be. Although we have now had four bears participate, we are hoping to obtain data on at least twice that many individuals before analyzing it. However, I am optimistic about Francis; his willingness to address his initial reticence about the waterfall shows me that this bear has some level of confidence that could help him one day to become a new mate of our female, Marcella. What a success that would be, since the Bornean sun bears are so in need of a boost to their population in U.S. zoos!

Come visit the Sun Bear Trail in Asian Passage and keep an eye out for Francis. You can identify him by his sleek frame (as compared to Marcella) and the brown fur above his eyes. And cross your fingers for his future and the future of Bornean sun bears everywhere!

Suzanne Hall is a senior research technician for the San Diego Zoo Institute for Conservation Research. Read her previous post, Picture-Perfect Pair.


Big Move for Sun Bears

Marcella and Palu during earlier times.

A few weeks ago, when giant panda Yun Zi’s weaning process was completed via his move to the upper bedroom area (see post Panda Yun Zi: On His Own), all eyes were on the pandas to see how they would manage this transition in their lives. Overshadowed by this event was the weaning, separation, and transition of our sun bear youngster, Palu. On the very same day that Yun Zi moved, Palu was also permanently separated from his mother.

You may recall that Palu was older than Yun Zi, born in October 2008, but had remained with Marcella, his mother, even after his sibling Pagi was weaned and moved several months ago. Although the mother-son pair had been ready to wean for some time, the logistics of weaning Palu and having him remain at the sun bear facility would have made things difficult. Unlike with the pandas, the sun bear facility does not have a distant space that a recently separated bear can be housed in. If we weaned Palu, he and Marcella would have continued to reside in proximity to one another and would be constantly exposed to each other’s smells and sounds. This situation would have impinged upon each bear’s ability to transition to independence. So we waited for a better option.

Recently, we have determined that Palu will be moving to another zoo. We are excited for him, as he will ultimately have the opportunity to be paired with a female sun bear for potential mating opportunities once he matures. This impending transition also allowed us to move Palu away from his mother into a behind-the-scenes holding area as he prepares for his journey.

Staff had seen signs that weaning was occurring naturally for these animals. The two kept away from each other when on exhibit, interacting very rarely. Nursing had not been seen in some time. Keepers had noticed indications that the two were actually scuffling from time to time. And finally, Marcella appears to have resumed her cycling, and for the sake of genetics we needed to move Palu to his own space.

Palu’s regular keeper, Crystal, had been training him to prepare Palu for his trip to the holding area. She described his attitude during training as “very focused.”  This really paid off, because during the move he was very calm, never vocalized, and immediately took to exploring his new surroundings. Clearly he was well prepared for the short trip in the crate!

In the time since, Palu has become a big hit with the staff who work near his new off-exhibit home. When he isn’t digging holes big enough to get his whole body into, he is entertaining us with his goofy antics. Like a sub-adult panda, Palu is at a social stage and appears to relish the opportunity to ham it up for staff. We will certainly miss him when he leaves.

We expect to say goodbye to Palu in about a month’s time. He will make the trip to his new home with a few trusted staff members at his side. They will help him settle in. And for the time being, Marcella will be the only sun bear on exhibit at the San Diego Zoo. That will be a short-lived prospect, however. When our staff returns, they will be bringing with them a souvenir: an adult male. We hope he’ll be a new addition to the breeding success we have had! This is incredibly important for the species, as sun bears are one of the rarest bears on the planet. Unfortunately, breeding efforts for the Bornean subspecies thus far have not been what is needed to sustain the subspecies in North American zoos.

In the end, the silver lining of Palu’s departure is that this move opens the door for fresh breeding opportunities at two zoos.  We wish him the best!

Suzanne Hall is a senior research technician for the San Diego Zoo Institute for Conservation Research.


Moving Right Along

Things have been going well for pandas Yun Zi and Bai Yun during this first step of the weaning process (see previous post, So Far, So Good…). Although the door between them has been closed for a few short hours each day, the two animals are apart much of the remainder of the day, by choice. Keepers are reporting that most of the fecal piles left by the bears throughout the day and night place mother bear in the left-hand exhibit and her youngster on the right.

Yun Zi really seems to have taken to the right exhibit, Gao Gao’s former home. Observers have noted in the last few days several instances in which mother and cub have been together, only to have Yun Zi trot off to “his” space for a few hours. It appears that his increasingly large frame is best supported by the big deadwood structures found in that exhibit in a way the old elm tree on the left side could not offer him. He has also been enjoying the comfort of the top of the old den in that exhibit, like his father before him.

With the reassurance of Yun Zi’s success during this first part of the weaning protocol, we are set to move to Step 2. Tomorrow, February 1, we will begin lengthening the separation time. The door between bears will close as usual in the morning and will remain closed until early afternoon. They will receive their mid-day feed separately but be reunited before staff leaves for the night. As before, we will hold with this pattern for a few days to allow the bears to acclimate to this change.

We’ll continue to keep you apprised of the changes during this process as we move forward.

Suzanne Hall is a senior research technician for the San Diego Zoo Institute for Conservation Research.

Video of Yun Zi and Bai Yun is now posted, and additional images of Yun Zi have been added to our Panda Photo Gallery.


Aerial Survey of Mammoth Importance

The San Diego Zoo collaborates on elephant conservation in Africa with the nonprofit organization Elephants Without Borders, based in Botswana. Read Kelli’s previous post, Wild Elephant Rainbow Spirit.

Elephants are plentiful along the Chobe River.

We are very pleased to share with everyone what has kept Elephants Without Borders (EWB) busy the last few months in the field. With the support of Botswana’s Department of Wildlife & National Parks and the San Diego Zoo Institute for Conservation Research, we finally completed flying a mammoth aerial survey, counting elephants and wildlife species throughout northern Botswana. Piloted by Mike Holding, our 4-member survey team flew the  last 3 months, approximately. 250 hours, in a small, single-engine plane to complete the survey. The distance we covered was about 43,000 kilometers (26, 720 miles), flying along straight transect lines over Botswana’s varied terrain. That amount of flying is longer than the circumference of the Earth at the equator!

The study area essentially encompassed the entire elephant range in northern Botswana of approximately 115,800 square kilometers (44,710 square miles). Over high density wildlife areas, such the Okavango Delta, the sampling coverage was about 22 percent, the highest survey coverage ever flown over a vast area of northern Botswana, making this Botswana’s first aerial survey conducted with such a high sampling intensity. This is important, because the higher the sampling coverage, the more precise the population estimates. (Learn more about aerial surveys.)

An aerial view of zebras in Makgadikgadi.

Wildlife species we counted included large and small herbivores; predators were also noted when seen. Other observations included types of elephant herds (bull or family groups), elephant carcasses, elephant bones, and, if possible, whether tusks were intact or missing. We also recorded observations of selected large birds and nesting sites. Due to the growing concern on what possible impacts elephants are having on large trees in Botswana, and considering baobabs are an iconic tree in the country, we also counted baobab trees and took note of their size and possible damage they may have sustained. We made additional notes on environmental conditions, such as the extent of bush fires and the structural integrity of Botswana’s veterinary fence lines and whether livestock or wildlife had crossed them.

The information on elephant and wildlife numbers, distribution, movements, and demographic characteristics from this study will be incorporated into population models to better understand a variety of research and management questions relating to wildlife ecology and conservation management in Botswana.

This map shows the transects flown for EWB's survey. Click on all images to view in larger format.

We plan to publicize the results of this important aerial survey at an official launch of the report in early January. In addition, we plan to give several presentations on the project results to key stakeholders. The primary objectives of these presentations and meetings will be to share information obtained from this study and from the on-going research activities of EWB, identify priority areas for wildlife corridors, and develop strategies for promoting wildlife conservation in the region. We hope that the results of this collaborative survey with the Department of Wildlife & National Parks will have fundamental conservation management implications for land-use planning and conservation efforts in Botswana.

Kelly Landen is the director/program manager for Elephants Without Borders.

Watch the San Diego Zoo Safari Park’s African elephant herd daily on Elephant Cam.


Sun Bears: Next Steps

Sun bears Palu and Marcella.

It has been some time since sun bear Pagi left us to travel north to her new home (see Overseeing Bears: The SSP) . Our staff has maintained regular contact with the keepers in her new home, and all reports are that she is thriving there. After initially developing a relationship with her older sister, Bulan, it appears that the young girls have had a falling out. No matter, as Pagi is happy interacting with her keepers and continues to enjoy training opportunities with them.

Palu is still with his mother, living comfortably on the Sun Bear Trail  in the San Diego Zoo’s Asian Passage zone. Despite Palu’s continued presence, Marcella is probably not supporting his nutritional needs significantly; nursing is still seen, though rarely. Palu is a big, growing boy—he is heavier than his mother by several kilos—and his calories come primarily from food provisioned by keepers. Since the time of maternal dependence is ending, Marcella’s body is returning to its not-so-maternal baseline state.

As a result of this, Marcella has recently shown us some signs that she may have had a mild estrus. Her behavior changed, and she became more solicitous with Palu. For his part, the young male seemed confused by these changes, but it got us thinking that it’s time to separate these two animals before Marcella has a solid, fertile estrus. We don’t think it is very likely that Palu is reproductively mature yet, at age two, but we can’t be certain that he isn’t capable of fathering his own offspring.  

Marcella typically cycles every three to five months. This is actually a pretty active estrus schedule for a Bornean sun bear in North America. Some females don’t cycle at all, and many cycle only once per year. Even with more frequent estruses, we can predict a quiet period for Marcella until sometime in the spring. During this lull, we will need to arrange for our big little bear to wean.

Marcella and Palu will settle into separate lives in the next few months. Keep an eye on Sun Bear Trail, as there will be some interesting bear behavior there in the near future.

Suzanne Hall is a senior research technician for the San Diego Zoo Institute for Conservation Research Read her previous post, 300 Pandas.