Author Archive

Turtle University

by | June 28th, 2011

Newly hatched western pond turtle

Its turtling season at the Oakland Zoo again! Each summer our zookeepers team up with biologists and students from Sonoma State University to study the western pond turtle. Turtle nesting season is in full swing and California’s only native aquatic freshwater turtle has been an enigma to researchers for years. This is the fourth consecutive year that zookeepers have spent in Lake County and our knowledge of this species of special concern has increased exponentially. Here is just a short run down of a few of the things we have learned about western pond turtles through our collaborative research:
First, we were surprised to discover just how dry the nests were. Aquatic turtles are usually expected to have very moist nests, but not our western pond turtles. Based on our observations at the site, we created a very dry vermiculite mixture in which to incubate the eggs we collected. Several experts expressed concern about the lack of moisture in the mixture, but our guess was correct and we had a 90% hatch rate the first year.
One little known fact about many reptile species, western pond turtles included, is that the sex of the hatchling is determined by the temperature at which the egg is incubated. Along with our dry vermiculite mixture, we also set up five separate incubators at five different temperatures. The hatchlings were carefully marked with numbered dots so we knew exactly which clutch and incubator they came from. The hatchlings were then raised here at the zoo for about ten months, until they were big enough for a small endoscopic surgery to determine their sex. This data was then correlated with the incubation data and we now know the exact temperatures that produce male turtles versus female turtles.

Dr. Andrea Goodnight uses an endoscope to identify a turtle's sex.

As time went on, our project expanded and we also began to incubate nests in the field. This requires careful placement of high tech temperature and humidity sensors inside the nests and then covering the nests to secure them against predators. The wide range of temperatures in even a single day took us by surprise. Who would have guessed a difference of up to fifty degrees in one twenty-four hour period.
This is a project that is near and dear to our hearts, not only because it is a native species, but also because it is a project that zookeepers can be directly involved in. Just days ago, two keepers went to the lake to use telemetry equipment to track nesting females while other keepers were here at the zoo caring for last year’s hatchlings, who will be released at the end of this month. As we continue to progress in this conservation project, we hope to learn even more about this special animal.

Baby Otters!

by | May 11th, 2011

Otter pups at 1 day old

What’s more amazing than baby otters? Nothing! This year, our 4 year old female North American river otter gave birth to her first litter. First time moms often make keepers nervous since we never know how they will do, but Ginger has turned out to be a pro!
Ginger joined us here at the Oakland Zoo in 2008, when she was just one year old. North American River otters are not very prolific breeders, so AZA makes annual breeding recommendations. When Ginger came to us, she was still a bit too young to breed, but we knew that the AZA eventually wanted her to breed with our 12 year old male, Heath.
River otters are one of the few species that exhibit a phenomenon called delayed implantation. Essentially, otters breed in the spring but the fertilized egg doesn’t actually implant until fall! So how does one plan for such a unique pregnancy? As it turns out, hormone levels can be measured in otters’ feces! Our keepers collected samples from Ginger four times each week and mailed them off to Cincinnati to be tested. In December, we got the word that Ginger’s progesterone had spiked and that she was likely pregnant with a due date sometime between February 15th and 23rd.
Now the preparations really ramped up! The keepers had meetings with the vet staff to prepare for any and all possibilities. Cameras were set up in denning area. Supplies such as extra towels, an infant scale and thermometer, and data recording sheets were prepared and brought down to the night house. We also requested additional help from our Behavioral Observation Team, a group of dedicated volunteers who spent hours each week watching Ginger and observing her for any changes in her behavior. We also kept close tabs on Ginger’s weight and appetite at this time. The keepers had been training her to jump on a scale using positive reinforcement since she arrived, so they were able to monitor her weight several times each week and increase her food as necessary.
On February 15th, keepers arrived to find Ginger not only ravenous, but cranky as well! She wanted nothing to do with the two male otters with whom she shares her exhibit. A quick peek confirmed that she had given birth to TWO pups overnight (two to three is average for otters)! We quickly weighed them and put them back to cause as little disturbance as possible. The pups then had their first vet visit the following day where they were pronounced healthy!
The work doesn’t end there, however. Our otter observers now had to watch Ginger and the pups on a closed circuit monitor to ensure that Ginger was keeping them warm and that they were nursing. Otter pups are born blind and helpless, about the size of a stick of butter, so they depend on their mother for everything! Thankfully, Ginger is the best otter mom we could have hoped for and the pups quickly thrived under her care!

Twice each week, someone from the vet staff would come down to examine the pups. We monitored their temperatures, weight gain, hydration, respiration, and heart rates. Since Ginger had to be separated from the pups during the vet visits, we kept the checks down to no more than 10 minutes to minimize the stress on both the mother and the pups.
We are so happy to have healthy baby otter pups and we are so proud of Ginger. For more photos and video of our otter pups check out our otter webpage!

First veterinary exam, Day 1


Weighing pups, Day 30

First swimming lessons took place in a shallow water tub, Day 55

First time swimming in the "Big Pool" on exhibit with mom, Day 75



21st Century Zoo Keeper

by | January 21st, 2011

Zoo keepers from all over the world studying training and enrichment at the Oakland Zoo.

Zoos sure have changed since the 19th and even 20th centuries. The most obvious changes have been in the housing of animals. Sterile concrete floors surrounded by metal bars have been replaced by natural substrates, rockwork, water features and climbing structures. What is not always as obvious is the difference in the zoo keepers! Unskilled laborers who merely raked, hosed and delivered food have been replaced with knowledgeable professionals who provide for the animals’ psychological needs in addition to their physical needs. 21st century Zoo keepers are compassionate, aware, and educated. How does this change take place? Where does an enthusiastic new zookeeper go to learn how to address an animal’s psychological needs? Where do experienced keepers go to hone their skills and learn the newest techniques? To the Oakland Zoo of course!
This is the second year in a row that the Oakland Zoo has hosted the Training and Enrichment Workshop for Zoo Animals (TEWZA) put together in conjunction with Active Environments and The Shape of Enrichment. Zoo keepers from all over the US and even as far away as Africa spent a week at the Oakland Zoo learning positive reinforcement training and effective enrichment strategies. In addition to classroom work and lectures, workshop participants were able to practice their hands on skills with some of the Zoo’s animals.
Training classroom work included lectures on operant conditioning terminology, socialization training, desensitization and acclimation, problem solving and shaping plans. Many of our own Oakland Zoo animals and keepers demonstrated training techniques for the workshop delegates. The participants were then broken up into smaller groups to write shaping plans for new behaviors before going out into the zoo to practice what they learned!

An anaconda explores novel substrate enrichment provided by the participants.

A gibbon enjoys a rope ladder provided by the particpants.

Another aspect of the workshop focused on enrichment. Lectures included the effect on animal welfare, setting goals, planning enrichment appropriate to the species, observation strategies, data collection, and safety. The participants separated out into small groups once again and planned enrichment for their designated species, including going through an approval process, building the devices and observing and evaluating the effectiveness of the devices. Several of the Zoo’s animals benefited from these enrichment projects!

Workshop participants observe an Aldabra tortoise participating in a voluntary blood draw using positive reinforcement.

Workshop Participants collect data on the effect their enrichment has on the animal's behavior.

More and more we are seeing zoo keeping as a holistic experience. By incorporating the psychological aspects of training and enrichment into our daily routines we are truly entering a time of renaissance for our profession. In the 21st century we are not merely keeping zoo animals, we are enriching their minds and their lives.

Welcome to Our Family

by | August 26th, 2010

The Oakland Zoo functions in much the same way that my family does…or perhaps it’s my family that functions like a zoo. In any case, a new family member is always cause for celebration whether it involves a wedding, a birth or an adoption, and the zoo is no different. When an animal comes to us from a different facility, it is much like an adoption, there is a lot of paperwork and a huge adjustment period for both the animals and the keepers. There is also a strong desire for the new member to integrate into the group and become a full fledged family member. Most often, those new family members come from another zoo where they have full medical records, and experience dealing with humans and other animals, however, sometimes we make the decision to accept animals from other, often private, situations with less certain histories. No matter what the animal’s history is, the most important consideration is their welfare.
Because of the our strong commitment to animal welfare, the Oakland Zoo opposes using animals in entertainment, yet thousands of animals are still in these situations in circuses and private ownership throughout the country. This situation is hardest on intelligent and social animals like apes and elephants. In fact, in a study published in Science in 2008, the proliferation of chimpanzees in film and TV has the led the general public to mistakenly believe that chimps are not endangered ( In 2009, more than 30 chimps were being trained and used for entertainment in the United States. In 2010, thanks to the Oakland Zoo, Chimpanzee Species Survival Plan (SSP) and the Houston and Maryland Zoos, that number is now down to 19.

At the end of 2009, the Oakland Zoo was approached by the Chimp SSP about adding two new male chimps to our current group. They were retired entertainment animals whose owners had decided it was time to place them in a permanent home. One of the primary concerns for the Oakland Zoo was that we did not want our acceptance of these two chimps to create more space for new animals to be brought into an entertainment situation. Many entertainment animals are pulled from their mothers at an early age and not allowed regular contact with members of their own species. Fortunately, the couple that owned this group was knowledgeable about chimp behavior and socialization and all fourteen of their chimps interacted daily with other chimps. The couple started their collection with unwanted chimpanzees from other places and turned to entertainment as a method for supporting their growing brood. Recently they decided to get out of the entertainment business entirely and find permanent, acceptable homes for all 14 of their chimps. While chimps in film and TV may be contrary to the Oakland Zoo’s view, we nevertheless applaud the couple for their commitment to ensuring that all of their animals will be taken care of for the rest of their long lives by making the difficult decision to give them up and place them in AZA accredited zoos.
Another consideration for us was the welfare of the group of chimps already living at the Oakland Zoo. Chimps in the wild live in large groups composed of both males and females of all ages. Studies indicate that males interact more with each other than females do or even males and females together. Our current group was composed of one male with four females, so adding additional males would create a much more natural group for our chimps. But adding additional animals is never taken lightly, the keepers, supervisor, and curator all met with the couple and the SSP chair and visited the chimps before making any commitment. Once we felt that this was something that could reasonably be taken on, the Oakland Zoo vets arranged dates with the vets from the Houston and Maryland Zoos to perform physical exams on all of the couple’s chimps to ensure that they were healthy and didn’t carry any foreign parasites that could make our zoo chimpanzees sick. Additionally, our maintenance department worked hard to create safe crates to transport the chimps and the plans were finalized in the spring for each group going to the various zoos.
In May of 2010, Eddie and Bernie arrived at the Oakland Zoo, excited to begin their new lives! Eddie is 20 years old and the dominant of the two brothers. He is clearly the peacekeeper in the group and values social structure. He has quickly earned the respect of his new family and has become best buddies with Moses, who is thrilled to have some male companionship.
Bernie is 16 years old, he is highly intelligent and outgoing. He doesn’t share Eddie’s confidence, but enjoys interaction with his keepers as well as the other chimps. Bernie and Moses got off to a rough start, but Eddie has done a great job of facilitating interactions between the two of them and they are quickly becoming friends.
Blending two groups of chimpanzees into a single family is more difficult than you might think. Introductions, or “intros” as we call them, can be very risky and there is always the chance that an animal can be seriously injured. To reduce this risk, the chimp keepers did mountains of research, talking to other chimp keepers and sending out surveys. We had more planning meetings than I can possibly count, sometimes as often as twice a day! Our final plan involved each of the chimpanzees meeting one on one to give them some time to get to know each other before bringing the group together as a whole. This was really our chance to see each animal as an individual and observe how they would relate to each other. Just like some people relate better to each other than others, so do chimpanzees. The process took more than two months to complete during which the chimp keepers worked harder than they ever have before. Each and every one of them came in early, stayed late, and gave up days off and some even spent a few restless nights sleeping at the zoo, all to ensure a smooth transition for all the chimps. I am so proud and honored to work with such dedicated people! The end result is a more natural group of chimpanzees including several males and several females which means a more natural social structure and increased welfare for all! Welcome to our family, Eddie and Bernie – it’s your zoo now.

My Tortoise Is Smarter Than Yours!

by | July 12th, 2010

Summer is a busy time at the Oakland Zoo and the Wayne and Gladys Valley Children’s Zoo is no exception! You may have noticed the number of Aldabra Tortoises shrinks every summer and returns every winter. At the beginning of every summer, we move the male tortoises to a large grassy holding area for a few months for two reasons. First, the turf just needs a break! Grass is the primary diet for these guys and they graze it down to almost nothing, so in the summer we give the lawn a break to fertilize and reseed. Second, there is a theory in the reptile world that “absence makes the heart grow fonder” and many herpetologists believe that separating males and females for a few months increases the chances of them breeding when they finally get back together.

Great idea, but….how do you move a 500 pound tortoise? I have to admit that this is not one of my favorite jobs. First you have to get them out of their favorite mud wallow, not an easy task. By the time we finally get them out of the mud, we keepers usually look like the swamp monster! Then, we have to carry the slippery tortoise across the yard, out the gate and load them into a truck. It takes at least six people to lift a tortoise onto the back of the pick-up truck and it’s not like they sit still once they are there. Five keepers then have to sit on the back of the moving truck with him and try to keep him from climbing out, and believe me they are even stronger than they look!

Keepers Adam Fink and Ashley Terry leading Gus out of his mud wallow.

Adam Fink targets Gus across the yard whil volunteer Taylor Vanden Broek.

Adam Fink leads Gus across the yard.

For the last year, the keepers have been working on a training program with the tortoises using the same positive reinforcement techniques that we use with many of the other zoo animals. It’s pretty simple; the tortoises have a 10 inch square of plywood each painted with their own color called their “target.” When they touch the target, they get a piece of carrot. Who would have guessed that such a simple behavior would be so powerful!

Gus allows Ashley Terry to rinse off the mud.

This year, when it was time to move Gus, he was happily settled into his giant mud wallow with his two favorite girls. I must admit, I groaned a bit at the prospect of having to extract him. But, the power of positive reinforcement prevailed! As soon as Gus saw his red target, he got up and followed the keepers out of the mud wallow and all the way across the yard to the gate of his own free will! He even let us rinse the mud off him with the hose! Granted we still had to lift him into the truck, but it was a lot easier on our backs because he was so much closer! And, we did still get a bit muddy, but at least we were still recognizable as keepers, not the swamp monster. The best part is that Gus CHOSE to move! We didn’t force him; he cooperated with his keepers based on his relationship with them and the positive reinforcement. In fact, we are continuing to use these techniques to train other behaviors such as weighing, nail trims and blood draws. Training tortoises is truly progressive animal management, which is something the Oakland Zoo excels at! And, Gus is just as happy in his summer home as he is in his winter home!

Ashley Terry, Jen Jelincic and Taylor Vanden Broek help Gus into the truck.

Hairy People

by | March 8th, 2010

Chimpanzee, Photo Courtesy of Oakland Zoo

Why are chimpanzees so fascinating to us? Is it because they are so much like us, sharing 98 percent of our DNA? Does this cause people to minimize their wildness? Or is it the reason we forget entirely that they are inherently wild animals? Does our propensity to anthropomorphize diminish our respect for these majestic primates?
According to a 2008 study published in the journal Science, it does. The results of that study indicated that the frequency with which we see chimpanzees in movies, TV, and commercials leads the general public to believe that chimps are not endangered. In fact, they are listed as endangered by the World Conservation Union (IUCN) Red list. Chimpanzees are already extinct in 4 of the 25 countries in their natural range. Since the 20th century, the estimated chimpanzee population in the wild has been reduced by a staggering 70-80 percent.

Chimpanzees in captivity however, are another story. More than 2000 chimps live in captivity right here in the US. Half of those are in biomedical research and about a quarter of them live in sanctuaries. Only 12 percent of chimps living in the US live in AZA accredited zoos. That leaves nearly 250 chimps in unaccredited facilities or private ownership. In fact, there are over 100 chimps documented as private pets in the US.

How did we get to this point? While the IUCN may list chimps as endangered, it has no recourse for individual countries. Each country makes their own list of endangered species that are protected by their local laws. Chimps in the wild are threatened by habitat destruction and bush meat consumption, but it is all too easy to point the finger at a country halfway across the world. We can and should support these far away places. The Oakland Zoo has made a huge impact by supporting the Budongo Snare Removal Project.


However, there are still 2000 chimpanzees in the US, and they didn’t get here by accident. Chimpanzees are the only species that our own government has double listed in our endangered species laws. This is confusing because the United States government classifies WILD chimps as “endangered” and CAPTIVE chimps as “threatened.” This means captive chimps are not afforded the same protection under federal law that every other endangered species receives. Therefore, private breeders are selling chimps to unsuspecting families as pets. Chimps are dressed up in clothes for our entertainment in movies and TV.  Because chimpanzees are portrayed this way, many people lack the understanding and appreciation for one of the world’s most intelligent animals.

As an AZA accredited zoo, the Oakland Zoo participate s in the Chimpanzee Species Survival Plan (SSP). Recently, the chair of the Chimp SSP began an ambitious project to document ALL chimpanzees living in the US and educate the public about their plight, not only in the wild, but here in our own country. The website,, is not only educational, but gives us, as consumers the power to make choices in our daily lives that will affect how chimps are treated here, in our own backyards. Chimpanzees are not just hairy people; they are majestic, magnificent animals that deserve dignity and respect.