Conservation at the Zoo

Conservation at the Zoo

3

Condor Egg Fails to Hatch

This dummy egg looks just like a real California condor egg and serves as a placeholder.

This dummy egg looks just like a real California condor egg and serves as a placeholder.

As keepers, we often have the privilege to witness or even help usher in a new hatch or birth into the world. Of course, working alongside our excellent veterinary staff, we provide assistance and supportive care to maximize survivability, but sadly, sometimes it isn’t enough. We experienced this recently at our California condor breeding facility at the San Diego Zoo Safari Park when one of our condor eggs failed to hatch. This egg was expected to hatch under our experienced Condor Cam parents, Sisquoc and Shatash, who for the last two years have raised their chicks, Saticoy and Cuyamaca, under the watchful and adoring eyes of thousands of their fans. Saticoy is now flying free in Southern California, and Cuyamaca was recently sent to Arizona to be prepared for release there.

We usually remove the egg after it is laid so we can artificially incubate it and monitor its development without disturbing the very protective parents. While we are caring for the real egg, we give the parents a fake egg (called a dummy egg) to incubate. This dummy egg serves as a placeholder until the real egg is ready to hatch; without it, the parents would not accept the real egg when we would try to replace it in their nest.

While we were caring for Sisquoc and Shatash’s egg, we weighed it daily to track its weight loss, and we candled it periodically to monitor development inside the shell. During incubation, we noticed that the embryo was slightly in the wrong position to hatch—a malposition. Some malpositions are lethal or need our help to hatch successfully. This embryo’s malposition was not extreme and would not normally need our assistance. What was more concerning was the condition of the membranes surrounding the embryo: loose and saggy when they should have been taut. Concern grew that these membranes would cause difficulty in breathing for the embryo once it moved into the egg’s air cell to begin pulmonary respiration. The loose membranes could adhere to the embryo’s nostrils, suffocating it.

Despite 24-hour care from our keepers and a valiant effort from our veterinary staff, the embryo stopped breathing partway through the hatching process on Sunday, March 16, 2014. The egg was expected to hatch around March 20. The embryo and egg are now at our Pathology Lab; hopefully, we will have more information regarding the cause of death.

Egg mortality is highest at the beginning and at the end of the egg’s incubation period. Sometimes there can be a genetic issue causing the embryo to stop developing. Sometimes the egg can get too hot or too cold during incubation, the egg can get jostled, humidity can be too high or too low, etc. Despite setbacks such as this, our “hatchability” rate at the Safari Park is still very high at over 85% success, much higher than wild eggs that have to contend with nest predators, competitors, and a lack of veterinary support.

So, what’s next for Sisquoc and Shatash? They are still incubating their dummy egg perfectly and are being considered as potential foster parents if another condor egg needs to be parent-reared. They will still sit on the dummy egg, even after the due date of their original egg, but only for about a month or so. After that, they will start to tend to the egg less. We see this behavior in birds that are incubating an infertile egg or an egg that died during incubation. If another condor egg needs to be foster-reared, we can return that egg to their nest, and they will hatch it and raise it as their own. Their drive to care for an egg/chick is so strong that they don’t know or care if it’s not their egg. If another egg doesn’t need fostering, we will remove the dummy egg from their nest. They will then shift from nest-caring duties and spend more time in their flight pen. It may seem sad, but that is what happens to wild birds whose eggs do not hatch.

What’s next for Condor Cam? We have moved the camera to a different nest to show you another of our awesome condor pairs, Sulu and Towich, whose egg is due mid-April. Stay tuned for a blog introducing the new pair.

Thanks so much for all of the comments and condolences regarding the loss of Sisquoc and Shatash’s egg. There are still 30 other California condors at the Safari Park that need us to give them the best care we can. With hope, luck, and your support, we can continue to maximize success for these magnificent birds!

Ron Webb is a senior keeper at the San Diego Zoo Safari Park. Read his previous post,
Egg-citing News on Condor Cam
.

35

What to Eat When There’s Nothing to Eat?

Bear ambassador Mi Ton Teiow finds relatively shallow snow, but no food, as the northern winter begins.

Bear ambassador Mi Ton Teiow finds relatively shallow snow, but no food, as the northern winter begins.

The answer? Nothing.

Most of us are familiar with the idea that some bears spend long periods of time in dens, inactive and not consuming significant amounts of food or water. Some bears in some locations survive eating nothing by doing almost nothing. They become inactive, which is sometimes called winter sleep or hibernation. Although you may be familiar with this aspect of bear ecology, have you thought about how incredible it is? These big mammals can go without eating or drinking for months, sometimes while birthing and nursing cubs, yet wake up without bedsores or weakened muscles! This is why the physiology of bears, including that of giant pandas and polar bears, has been a hot field of research.

The only way for a wild American black bear to survive for months without food in the northern U.S. is to save energy by hibernating in a safe, insulated den. The hole to the right of the tree trunk is the only obvious indication that there is an American black bear below the snow.

The only way for a wild American black bear to survive for months without food in the northern US is to save energy by hibernating in a safe, insulated den. The hole to the right of the tree trunk is the only obvious indication that there is an American black bear below the snow.

Although all female bears seclude themselves in dens to give birth to cubs, not all bears enter dens for long periods of time. There’s even variation within species in whether or not individual bears remain in dens or for how long. Researchers have found that in general, bears spend long periods in dens not to avoid cold temperatures, but to reduce their metabolic requirements when there is not enough food to survive environmental conditions. So, in the southern part of their range where their energy balance can remain positive, individual brown bears, Asiatic black bears, and American black bears may not den except to give birth. At last year’s meeting of the International Association for Bear Research and Management (see post, A Whimsical Bear Ambassador Arrives), Lorraine Scotson and Dave Garshelis reported that some sun bears might den for periods of time in the most northern parts of their range, meaning that non-reproductive denning may occur among at least half of the world’s bear species.

The holes melted in the snow are made by the black bear’s respiration.

The holes melted in the snow are made by the black bear’s respiration.

The giant panda is one bear species that has not been known to den in response to a relative lack of food, and perhaps it cannot do so. During the rare times when all the bamboo plants in an area have flowered and then died, the giant pandas have left the area in search of food; they have not entered dens. Perhaps this is because a bamboo die-off is unpredictable from the giant panda’s point of view, or perhaps this is because a giant panda eating bamboo cannot build up sufficient energy reserves to be able to wait out the lean time in a den, or maybe both factors play a role.

Adult polar bears also do not enter dens solely to avoid food shortages. Pregnant polar bears do spend prolonged periods of time in dens, but biologists think other adult polar bears don’t do so. However, polar bears in some populations regularly fast for extended periods when sea ice conditions don’t allow them to hunt. As for other bears, anything that causes a polar bear to expend more energy, whether inside or outside of a den, or to fast for a longer period of time, makes it less likely that the bear will survive. Climate change is doing just that by reducing the amount of sea ice available to polar bears: the bears expend more energy and go without eating for a longer period of time, creating a great challenge for the conservation of this species (see Polar Bears, Climate Change, and Mi Ton Teiow).

Hibernating bears often line their den with leaves, twigs, and grasses, insulating themselves from the cold ground and conserving additional energy.

Hibernating bears often line their den with leaves, twigs, and grasses, insulating themselves from the cold ground and conserving additional energy.

The Bear Specialist Group’s Ambassador Mi Ton Teiow recently made a visit to the northern US, where he found plenty of snow but little food for bears. After a short stay in this area, which receives an average of 45 inches of snow per year, the ambassador returned (fled?) back to sunny San Diego, where the last measurable snow fell on the city in 1967. The odds are good that Ambassador Mi will not be snow camping in San Diego any time soon.

Russ Van Horn is a scientist with the San Diego Zoo Institute for Conservation Research. Read his previous post, Courtship in Front of the Camera.

2

Egg-citing News on Condor Cam

A precious California condor egg is candled to check on fertility and condition.

A precious California condor egg is candled to check on fertility and condition.

We have good news to report: California condors Sisquoc and Shatash’s egg is FERTILE! Shatash laid the egg on January 22, 2014, and we are expecting it to begin the hatching process around March 18. So, it is approximately one-third of the way through its 56-day incubation period.

Condor Cam viewers have been watching Sisquoc and Shatash take turns caring for and incubating their egg. Well, actually, they’ve been caring for a wooden egg that we refer to as a dummy egg. We use a dummy egg as a placeholder until their real egg is ready to hatch. It’s not as if we don’t trust them with a real egg; on the contrary, they have proven to be very reliable parents! When we place the egg in an incubator, and let the parents sit on a dummy egg, we can more closely and conveniently monitor the egg’s progress and offer any necessary assistance without disturbing the doting parents.

We weigh the egg every day and candle it every few days. When we candle the egg, we hold it up to a bright light that illuminates the interior of the egg, allowing us to see inside. We can monitor blood vessels, membrane development, embryo growth, and movement. As of now, we can see the embryo, which is about 2 inches (5 centimeters) long, moving inside the shell; we can also see its eyes! By weighing and candling during the incubation period, we can make sure that the embryo is progressing normally, and if it isn’t, we can prepare to offer help if and when it is needed.

If all goes well during incubation, and the egg begins the hatching process, we carefully switch it with the dummy egg while the parents are out in the flight pen eating or sunning. They usually don’t even realize we switched eggs on them; they just return to their incubation duties.

As previously mentioned, both the male and female condor take turns sitting on the egg. An incubation bout may only last a few minutes before the parent gets off of the egg and leaves the nest box, or it may sit for the whole day. When the parents take turns on the egg, we call it a nest exchange. Sometimes a nest exchange is immediate: one parent enters the nest, and the other parent gets off of the egg and leaves. Other times, a nest exchange may be long, leaving the egg unattended for up to 30 minutes while the parents are outside eating, bathing, sunning, or socializing. During a long nest exchange, the egg cools down, but not usually enough to endanger the egg, especially with successful and experienced parents like Sisquoc and Shatash. Many times both parents are in the nest area—one may perch in the nearby roost while the other sits on the egg—seemingly keeping each other company.

During nesting season, California condors can be surprisingly territorial and defensive of their nest. Usually, they are very mild-mannered and calm, but when they have a precious egg or chick in the area, they defend it. One of the field biologists in California reported a pair of condors swooping and chasing a black bear away from their nest! Despite being very tough and strong birds, they can be very gentle when it comes to caring for their egg or their chick.

Keep checking in on Condor Cam to follow the progress of Sisquoc and Shatash’s egg and eventual chick!

Ron Webb is a senior keeper at the San Diego Zoo Safari Park. Read his previous post, A New Egg on Condor Cam.

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Tracking Safari Park Elephants

Swazi receive a GPS anklet to wear during Charlotte's study.

Swazi receive a GPS anklet to wear during Charlotte’s study.

The San Diego Zoo Institute for Conservation Research works closely with the elephants both at the Zoo and the Safari Park. We consider research an important part of advancing elephant care and welfare, as well as providing us with opportunities to apply what we can learn about elephants here to those in the wild. Our most current project looks at the effects of quality versus quantity of exhibit space on elephant behavior, walking rates, and stress-related hormones in an effort to improve the welfare of elephants in zoos. Elephants need a good amount of space to fulfill their physical and psychological needs. However, space may not be of any use to an elephant if it is predictable. An elephant may benefit more from a smaller, more dynamic space (quality) rather than a larger, less dynamic space (quantity).

The Safari Park’s African elephants have access to both the east and west yards via a hydraulic gate. This gate makes it easy to manipulate the space, or quantity, of the exhibit for this study. To manipulate the quality of the space, we present controlled food enrichment. Using five different manipulations of food enrichment and available space two times a week for three trial periods, we can assess the relationships between quality and quantity.

Each manipulation lasts 22 hours. I come in to do observations in two- and-a-half-hour shifts three times to assess the elephants’ activity patterns and behavioral diversity. (This is when you might see me on Elephant Cam!). Eight of the elephants are equipped with GPS tracking anklets. With the help of some innovative thinking, we have designed an anklet to house the GPS device as an alternative to the typical collar devices. The device records the coordinates of the elephant wearing it every five seconds. At the end of the 22 hours, the GPS data is downloaded and sorted, and walking rates along with distance can be calculated.

The Safari Park's elephants stroll through the morning's mud.

The Safari Park’s elephants stroll through the morning’s mud.

Lastly, in order to examine the stress levels of the elephants, we collect both fecal and saliva samples representative of the time period of interest. Using both techniques allows us not only to gain a more robust picture of the amount of stress hormones present but also gives our endocrinologist an opportunity to perfect and define the methodology of these hormones via saliva samples, a technique which has been understudied in elephants.

It takes a lot of people (and elephants!) to make a study successful. The Elephant Team plays a huge role in helping us design and achieve solid research that can help elephants in a variety of places and situations. So far for this project, we have already found some potentially interesting results in regard to our elephants’ walking rates. I am excited to carry forward with the trials of the project. Stay tuned for another blog update when the study is finished!

Charlotte Hacker is a research technician for the San Diego Zoo Institute for Conservation Research.

26

Bear Ambassador Learns Importance of Plants

Ambassador Mi Ton Teiow explores some bamboo growing at the San Diego Zoo. This bamboo represents the incredible horticultural collection of San Diego Zoo Global and a key component of giant panda habitat.

Ambassador Mi Ton Teiow explores some bamboo growing at the San Diego Zoo. This bamboo represents the incredible horticultural collection of San Diego Zoo Global and a key component of giant panda habitat.

We’ve mentioned in previous Bear Blog posts that some of the major threats to different bear species are habitat loss, or habitat degradation, or habitat fragmentation. As you can tell, for bear conservation it’s important to consider the amount and quality of bear habitat. For food, bears (except for polar bears) rely on plants. Thus, people concerned about bear conservation often become concerned about the conservation of the plant communities on which the bears depend. Although San Diego Zoo Global is involved in conservation of animals, it also does a lot of work with plants.

Recently I talked to botanists and horticulturists at the San Diego Zoo, and our whimsical Bear Ambassador, Mi Ton Teiow, was able to visit plants from bear habitats around the world. You might know that our horticultural staff grow most of the bamboo eaten by the giant pandas or the eucalyptus eaten by the koalas, but that’s just the beginning of what they do! I knew that certain parts of the Zoo contained plants related to some I’d seen in Andean bear habitat in the cloud forest of southeast Peru, but our horticulturists pointed out close relatives of plants that are important to Andean bears in the dry forest of northwest Peru, as well as plants from Australia, Hawaii, and Africa.

This flowering powder puff tree (Calliandra haematocephala) may catch your eye, but there’s more to the plant collection than what meets the eye.

This flowering powder puff tree (Calliandra haematocephala) may catch your eye, but there’s more to the plant collection than what meets the eye.

One reason they are able to grow such a diversity of plants at the Zoo is its variation in topography, which helps create a wide range of microclimates. I was surprised to learn that during winter, certain parts of the Zoo may receive frost at night! Of course, another reason the horticulture staff is able to grow such diverse plants is their research to understand just what the different plants need to grow and reproduce. Sometimes this research requires them to conduct experiments such as those in the lab to determine the best conditions for propagating orchid seeds, or field trips like those to investigate wild fig trees.

San Diego Zoo Global grows plants for many different reasons, and sometimes because the plants themselves are of conservation concern, plant species can be endangered, and captive reproduction can be an effective tool for plants as well as animals. In addition to plant conservation efforts, horticulture staff grow plants for several reasons related to animal husbandry. As I mentioned earlier, some plants are fed to the animals, providing them with more natural sources of nutrition than they would get otherwise. Parts of other plants are given to animals as a form of enrichment, especially because of their scents. When an animal shreds a few branches it’s been given, the animal is performing a natural behavior in a renewable manner: the horticulture department will grow more!

This diversity of plant species and structure may resemble tropical bear habitat, but it’s actually part of the horticultural collection at the San Diego Zoo.

This diversity of plant species and structure may resemble tropical bear habitat, but it’s actually part of the horticultural collection at the San Diego Zoo.

Woody plants are also used as structures in the animal enclosures. Large limbs, logs, and sometimes stumps are placed so that animals have items to rub on, climb on, and sometimes sleep upon. You can probably see our bears interacting with their log “furniture” any time you visit the Zoo. And, any time you visit, you can pick up a free map and take yourself on a self-guided walking tour of the botanical collection surrounding you. If you’re able to visit the Zoo on the third Friday of a month, you can explore the plant collections further. On those Fridays, called Plant Day & Orchid Odyssey, you can take a free narrated botanical bus tour to learn more about the plant collections, and you can visit the orchid greenhouse, which is home to more than 3,000 orchid plants!

The next time you’re visiting the San Diego Zoo or Safari Park, or a zoo elsewhere, take a closer look at the plants; they’re a whole lot more than “just” landscaping; they’re food, furniture, and enrichment for the animals and plant ambassadors of the habitats on which their wild relatives depend.

Russ Van Horn is a scientist with the San Diego Zoo Institute for Conservation Research. Read his previous post, Bad News Bears.

2

Beware of Crunchy Figs!

Here's a Moreton Bay fig fruit sliced in half.

The fruit of a Ficus sansibarica provides a cozy home for fig wasps.

Recently, the Wildlife Disease Laboratories received an interesting request from Seth Menser, a senior horticulturist at the San Diego Zoo, asking if we could take pictures of plant parts under the microscope. “I would really like to do a couple of shots of a fig cut in half with the fig wasps still inside. I have the figs needed for the shots. And, if you have never seen inside a fig, with the fig wasps, it is a very incredible thing to look at!” We were curious, so agreed to help.

Fig wasp

This amazing view of a fig wasp was taken in our Wildlife Disease Laboratories.

Seth brought up several figs from a Ficus macrophylla, commonly known as a Moreton Bay fig. These trees originate in the subtropical rain forest of eastern Australia but do well in frost-free climates such as ours. These majestic trees can reach up to 200 feet (60 meters) with long, aerial roots providing the tree with additional support to hold up the immense canopy. Seth brought several figs ranging from green and firm to dark maroon with spots on the outside. He explained the life cycle of the fig and the fig wasp as he cut them in half, and we set up the cameras.

Here's one

This female fig wasp has her wings. Is she ready to fly to a new fig?

Ficus trees are unique because the flowering parts of the plants are inside the fruiting parts (figs), making it difficult for insects to pollinate the trees. Thus begins the cooperative relationship with the fig wasp. The fig provides refuge and a food source for the wasps, and, in turn, the wasps pollinate the tree.

To begin the cycle, a tiny female fig wasp enters into a narrow opening (ostiloe) at one end of the fig. While wiggling into this small hole, she often looses a wing or antenna. Safely inside, she lays her eggs. As she is wandering through the fig, she spreads pollen from the fig she hatched in, thus helping the fig tree produce viable seeds. The cycle of the female wasp is complete, and she dies. Her eggs hatch, and the young wasps grow, finding food and refuge in the fig. Interestingly, only female wasps grow wings and leave the fig. The males live their entire life in the fig. Their function is to mate with the females and chew small openings through the fig’s wall for the females to escape, and the cycle begins again.

How many fig wasps can you find in this fig?

How many fig wasps can you find in this fig?

We were totally fascinated by the story. Using a dissecting scope with a camera attachment and a macro lens on a photo stand, we were able to capture the intertwined life cycles of the fig and the wasp. We photographed the narrow ostiole of the immature smooth fig where the female enters. Mature figs looked completely different on the inside. They were soft and fleshy, with delicate flower structures and seeds lightly attached to the inner walls. Each mature fig contained several wingless male wasps, and Seth was lucky enough to find one female flighted wasp.

At first glance, theses tiny wasps are difficult to see. The magnification helps, but a keen eye is needed to see them. How many can you find?

April Gorow is a senior pathology technician with the San Diego Zoo Institute for Conservation Research. Read her previous post, We Never Stop Learning.

0

Bad News Bears

Ambassador Mi and flag

Mi Ton Teiow, an international ambassador for bear conservation, rests near the commonplace image of a California grizzly.

The last update on the travels of whimsical bear ambassador Mi Ton Teiow focused on a meeting of zoo professionals working for the conservation of polar bears, and an earlier blog described how the American black bear illustrates that our efforts for the conservation of bears can succeed. We can also fail.

The International Union for the Conservation of Nature lists the brown bear as a species of Least Concern, meaning that it’s not likely that this species will go extinct in the near future. That’s the good news. And now, the bad news: Even though this is the bear species found across the widest area and the most diverse habitats, and its global population is stable, some brown bear populations are in critical condition. It’s not yet clear whether the Gobi brown bear is a separate subspecies of brown bear or if it’s a population of Himalayan brown bear, but it is clear that the Gobi brown bear is in trouble, with a population of less than 30 individuals due to various impacts of human activities. Conservation and research efforts are underway, but in the face of long-term changes in climate, there’s no guarantee of success.

The Cantabrian brown bear in the Pyrenees Mountains of Europe has been the focus of long-term intensive conservation efforts, but it is still not certain if those efforts will be successful. Other regional populations of brown bears are also the focus of conservation efforts, such as the grizzly bears in the northern Rocky Mountains of the US, but ironically, all around me in San Diego are symbols and images of a bear that once was but never will be again: the California grizzly.

This street sign reminds us that this developed landscape was once good habitat for the California grizzly.

This street sign reminds us that this developed landscape was once good habitat for the California grizzly.

Ambassador Mi recently traveled to the San Diego Zoo Institute for Conservation Research, which is headquartered at the Beckman Center for Conservation Research near Bear Valley Parkway. Bear Valley was named for a famous male California grizzly, a species that has been extinct since around 1924. Yet images of the California grizzly are common and widespread throughout California on the state flag and the state seal. In addition, many people wear clothes bearing (yes, pun intended!) the image of a California grizzly. Many sports teams use the California grizzly as a mascot, and many places are named for it.

The California grizzly faced challenges common to other bear species: habitat loss, habitat fragmentation, and high mortality due to unsustainable hunting and deaths due to real or perceived conflict and competition with the modern human economies. Unfortunately for the California grizzly, its populations crashed before modern conservation thinking, science, and planning developed to the point where people in the western US were willing and able to prevent its extinction. When the last California grizzly died, we lost this bear’s value as a part of the functioning ecosystem, and we lost a wonderful product of evolution. If it still survived, the California grizzly would be a symbol of our willingness to share existence with a large carnivore, but when it went extinct, most of us did not recognize the value of large carnivores. We recognize those values now, don’t we?
There is absolutely no doubt that there would have been disadvantages to living near California grizzlies. The negative aspects of living among bears are often forgotten by urban dwellers, as those stories fade with the passage of time and changes in lifestyles. What we’ve remembered are the positive traits and values we project on the bear, so that now the California grizzly lives on only as a cultural cartoon. Can we prevent another bear from becoming a cartoon of a ghost?

Russ Van Horn is a scientist with the San Diego Zoo Institute for Conservation Research.

3

Sifting through Poop

A tiger's poop can reveal a lot of information to researchers.

A tiger’s poop can reveal a lot of information to researchers.

I sift poop for a living. Well, that’s not quite true! I study hormones, those tiny chemical messengers that circulate in your body and control all sorts of amazing things, like when to grow or feel happy or sad, and, what I’m interested in, when to reproduce. Poop is just where I find the hormones. I could look for them in blood, just like your doctor might. But I work with animals, and they would rather you didn’t take their blood—anyone interested in getting close enough to a rhino or tiger to take a blood sample? Besides, blood only gives me a snapshot of their hormones at that moment when it’s collected. Hormones just don’t hang around in the blood very long. They do their job and are removed, often ending up in poop. In fact, hormones accumulate in the poop. When I measure the hormones found in poop, I get an average of what’s going on for that animal over the last 12 or more hours, not just a snapshot. And it’s easy to collect! So that’s the why, the how is bit more involved.

Every day the keeper collects a fresh sample in a small plastic cup, then freezes it, which stops bacteria and mold from growing, and prepares it for the next step. The sample is then freeze-dried, just like coffee. Freeze drying removes the water and makes the sample stable for long-term storage at room temperature. Next the sample is crushed and sifted. This removes the undigested material that interferes with the hormones during testing. A small amount of this dried and sifted material is weighed out and placed in a container with a liquid solvent. The hormones come off the poop and move into the solvent. This liquid is saved, and the rest is thrown away. I now have a liquid, or extract, containing the hormones I’m interested in.

Since hormones are too small to count directly, even with a microscope, a small portion of this extract is subjected to a special test called an immuno-assay. The assay involves combining the extract with a solution of specially labeled antibodies that attach to the hormone I’m testing. Once combined with these antibodies, the hormone that was too small to see or count becomes visible in a special detection machine. The detection machine counts the hormone-antibody couplets, and then it’s an easy calculation to determine the hormone level for each sample and each day. Graph the data, and you get a hormone profile revealing the reproductive status of each animal indicating if she is cycling, pregnant, or about to give birth. This information helps our animal care staff make informed decisions about how to care for and manage each animal.

Alan Fetter is a laboratory manager for the San Diego Zoo Institute for Conservation Research.

1

Black Bears: A Conservation Success

There are American black bears in Zion National Park. Ambassador Mi Ton Teiow, the special traveling “ambassador” of the Bear Specialist Group, paused for a photo here.

There are American black bears in Zion National Park. Ambassador Mi Ton Teiow, the special traveling “ambassador” of the Bear Specialist Group, paused for a photo here.

After the recent meeting of the IUCN’s Bear Specialist Group and the International Association for Bear Research and Management in Provo, Utah, I explored some bear habitat between Provo and San Diego and was reminded that one bear species in North America is an example of great conservation success: the American black bear. The IUCN (International Union for Conservation of Nature) maintains the Red List of Threatened Species, which is a global list of species and their conservation status. The American black bear Ursus americanus is listed as a species of Least Concern, primarily for two reasons. First, overall there are a lot of black bears. There may be twice as many American black bears as all the other bears in the world combined! Second, most populations of American black bears are stable or increasing, making this a great story of how a species can recover through conservation action and human tolerance. Some local black bear populations are not doing very well, but overall the prognosis for the species looks fantastically better than it did 100 years ago.

When European settlers reached North America, black bears were found throughout much of Canada, the US, and northern Mexico. There are once again black bears in most of those areas. However, there was a great decline in the number and range of black bears until the early to mid-20th century. In fact, I think that if the IUCN Red List had existed 100 years ago, the reduction in numbers and range of the American black bear would have led it to be listed as Endangered, which is the same category of conservation concern as the giant panda is now!

What led to such a dramatic decline in American black bears? The main causes were habitat loss, habitat fragmentation, overhunting, and conflict between humans and bears. These are the same issues that still threaten most of the other bear species. It’s taken decades and a lot of effort by many national, state, and provincial governments, conservation organizations, scientists, educators, and citizens, but the recovery of the American black bear illustrates that conservation of bears can succeed.

How did the recovery happen? A wide variety of actions were taken in support of American black bear conservation, including habitat protection, changes in bounties and hunting laws, changes in programs mitigating human-wildlife conflict, and more intensive efforts such as translocations and reintroductions. It’s also helped that this bear is an omnivorous habitat generalist, so although it is restricted to forested habitats, it can and will learn to eat a wide variety of foods, and it can live in fairly dense populations. That means that a population of American black bears can survive in an area that would be too small to support a population of brown bears.

Researchers with San Diego Zoo Global have collaborated with others to investigate various aspects of the physiology and behavior of American black bears, both to understand this species better and as a means to better understand other bear species. Doctors Barbara Durrant and Tom Spady have described the seasonally polyestrus, promiscuous mating system of the American black bear, showing that ovulation and conception occurs in each of a black bear female’s estruses during a breeding season. DNA analysis of preimplantation embryos proved that if a female mates with more than one male during the same mating season, the cubs born in her litter may be maternal half-siblings and not full siblings. Barbara and Tom also investigated the potential use of the hormone leptin as a wildlife management tool to monitor the adiposity (fatness) of American black bears and found that serum leptin measurements markedly improved the resolution and accuracy of common field estimates of body condition in this species.

A sign in the Olympic Peninsula of Washington reminds people hiking and camping in the forest that their behavior can have negative consequences for bears.

A sign in the Olympic Peninsula of Washington reminds people hiking and camping in the forest that their behavior can have negative consequences for bears.

Did you know that bears hum? Megan Owen has worked with others to study humming by bears, which occurs in all bear species but the giant panda. Most humming is done by cubs and is generally associated with suckling; however, the exact function of this behavior is still unknown. The relative loudness and very persistent nature of humming are puzzling! Further, we still don’t know whether the hum is an acoustic signal or whether its associated vibration physically stimulates the mother, perhaps enhancing milk production. Megan has also researched the interactions between mothers and their young cubs, in hopes of developing a better understanding of maternal care behavior and the range of variation associated with maternal care and cub behavior. Understanding this process in black bears may help us better understand the process in other bear species as well, including brown and polar bears.

Although the overall picture looks good for American black bears, as populations of both bears and humans have grown, new conservation challenges have developed. Because American black bears are fairly quick to learn to feed on new food sources, whether or not those food sources are “natural,” black bears learn to feed on foods they get from humans, whether the humans want them to or not. This leads to new conflicts as the bears use their intelligence and strength to seek the most profitable food source available. If you are fortunate enough to live or recreate in bear country, you can help bears and bear conservation, and avoid damage and risk from food-habituated bears, by ensuring that bears don’t get access to any human sources of food. That includes foods like pet foods, seed in bird feeders, greasy barbecue grills, garbage, etc. With your help, the support of citizens like you, and effective conservation actions, the American black bear can continue to be a great conservation success story.

Russ Van Horn is a scientist with the San Diego Zoo Institute for Conservation Research. Read his previous post, Whimsical Bear Ambassador Arrives.

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Ending with a Bang

Six pups are stuffed in here!

Six pups are stuffed in here!

Our litters keep getting bigger. On August 28, 2013, our last pregnant female Pacific pocket mouse of the season gave birth, but the nest was so full of nesting material that the number of pups couldn’t be determined.

September 16, 2013, brought exciting news. As pups started emerging from the nest, we found out just how many had been hiding: five! If only every litter was this big, we would reach our goal number for reintroduction.

Today they are doing very well; they are bold little guys that aren’t scared of our predator stimuli. With this litter, we added three males and two females to the group. Yesterday they got new neighbors to associate with.

A Pacific pocket mouse pup has its first molt.

A Pacific pocket mouse pup has its first molt.

Now it’s down to planning for next season. We will examine behaviors during previous pairings and refine our pairing strategies to increase our success.

Amaranta Kozuch is a senior research technician at the San Diego Zoo Institute for Conservation Research. Read her previous post, Pocket Mouse “Pupdate.”