Conservation

Conservation

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Extreme Volunteerism: Bighorn Sheep Count 2015

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

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

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

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Bighorn sheep live in harsh, rugged terrain.

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

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

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

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

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

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

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Bonus sighting: a big, beautiful desert tortoise!

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

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

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

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

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

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

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One Step Closer To Fledging

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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Terns, Plovers, and People: Living in Harmony

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

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

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

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

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

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

 

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

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

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

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

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

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

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

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

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

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Seeding the Future

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Transplanting fragile seedlings is a delicate but rewarding task.

As a kid growing up on a ranch in rural Colorado, I never enjoyed sowing seeds or weeding in my mom’s vegetable garden. Ask me to feed the chickens, okay. Fix barbed wire fence? Sure! Do anything involving a horse? You bet! But spend an afternoon with a hoe and unending rows of potatoes? No way. I often reflect on that now when I’m working in the nursery at the Beckman Center leading a team of dedicated volunteers in propagating 20,000 native shrubs over the course of two years. Somehow a switch flipped in my thinking about tending to plants as soon as I started growing natives for restoration. Now I see time spent sowing, transplanting, and watering seedlings as some of the most enjoyable and relaxing aspects of a job that I love. The volunteers and I began propagating almost 20 species in April, and we’ll spend the summer and fall nurturing just over 10,000 plants to grow into half-gallon pots by the winter planting season.

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Native plant seeds are sprouted and raised in the nursery area at the Beckman Center for Conservation Research.

The plants that we’re growing here will be the foundation of restored habitat for myriad plants, animals, invertebrates and fungi that depend on quality Coastal Sage Scrub (CSS) habitat. I often find myself enchanted by the tiny, miniature versions of California sagebrush Artemisia californica, bladderpod Peritoma arborea, and white sage Salvia apiana growing in neat rows of pots, just waiting to get big enough to get transplanted into our restoration site at Lake Hodges. I’m excited about this project, which is a mix of applied restoration and theoretical research. We’re restoring over 20 acres of degraded CSS habitat that is part of a critical corridor of preserved land in San Diego County. CSS is declining throughout its narrow range in southern California, so we’re doing all we can to preserve and restore the CSS vegetation at Lake Hodges that was burned in 2007. Lake Hodges is the centerpiece of the San Dieguito River Park, a patchwork of open space extending from the coast near Del Mar up into the mountains of Julian. The Park is home to many of the rare species that contribute to San Diego County’s astounding level of biodiversity.

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These seedlings will be used to help restore Coastal Sage Scrub habitat at Lake Hodges.

Diversity is the focus of the research we’re growing plants for. We’re interested in how diversity affects the success of restoration efforts, so we’ll be planting in blocks that vary in number of species. If a block dominated by, say, Eriogonum fasciculatum (California buckwheat) performs better than a mixed block of eight different native shrub species, we may be able to refine our planting methods for future work accordingly. It’s this mix of working closely with native plants while trying to figure out what makes the system in which they’re embedded tick that makes me love restoration. The last eight years of so of growing native plants for work has also made me revisit my childhood dislike of vegetable gardens—I guess I better tell my mother I’ll help her weed those potatoes next time I’m home!

Emily Howe is a research coordinator at the San Diego Zoo Institute for Conservation Research.

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Plover Hide and Seek

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A snowy plover chick’s cryptic coloring helps it hide from predators. (Photo: Rachel Smith, SDZG at Marine Corps Base Camp Pendleton)

Well it’s finally here, SUMMER! As a born-and-raised San Diegan, I know that one thing is for certain this time of year: the beaches become a popular place to visit for some fun in the sun. Besides having to share the sometimes-crowded beaches with other humans, we need to remember that there are other animals that also live on the beach. I am fortunate to have the opportunity to work with two of those wonderful animals, the threatened western snowy plover and the endangered California least tern.

The snowy plover can be seen year round in San Diego, but the California least tern only comes to our shores during the breeding season, which is April through August. I’m sure if you’ve been anywhere near the tern breeding colonies, you will have seen these small white birds flying around like fighter pilots chasing one another and sounding like storm trooper ray guns. The plovers are small, sandy brown shorebirds with gray legs that hang out in the wrack line of kelp, eating as many bugs as they can get in their bills.

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Can you spot the snowy plover chick hiding in this vegetation? Click on the image to enlarge it. (Photo: Rachel Smith, SDZG at Marine Corps Base Camp Pendleton)

During the summer at Marine Corps Base Camp Pendleton, the beaches are full of plovers and terns nesting and raising their chicks. For both terns and plovers, it takes about four weeks for chicks to be able to fly. Thus, they have to rely on camouflage to evade the eyes of predators; as biologists and monitors, this camouflage can make it challenging for us to locate them. Plover chicks are particularly good at hiding. First off, for lack of a better description, they are adorable. They look like freckled gray cotton balls with legs. Those legs come in handy when evading land predators, especially as the chicks get closer and closer to fledging (meaning they can fly). Their first defense is hiding, especially when they are young, and these little guys are experts at hide and seek.

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There it is! Click on the image for a better look. (Photo: Rachel Smith, SDZG at Marine Corps Base Camp Pendleton)

We are always keeping an eye out for them, looking for clues based on the behavior of the adult plovers (especially adult males) but we don’t always find them. It’s amazing how well the chicks blend into the sand and vegetation. They practically disappear and you often have to be right over them to see them. Often, our best chance of seeing the chicks when we are out monitoring is using our truck as a makeshift blind to watch for them out foraging around in the dunes and along the water’s edge. Amazingly, the birds do not perceive the truck as a threat and we can get much closer when we are inside the truck than outside of it.

Another technique we use is to blend in by staying a long distance away and using a spotting scope or binoculars to watch the behavior of the adult male (who does the rearing of the chicks) to find out where the chicks are hanging out. Watching these chicks grow up to become fledglings is a real treat, especially when I see them trying out their wings and getting a little air for the first time. It just puts a smile on my face knowing they have made it and are pretty much all grown up.

So, while I’m out with my fellow biologists doing our part to help protect these amazing animals, you as beach goers can do your part by respecting closed beach areas even when it is crowded, and keeping the beaches clean not only for each other but for all the animals that live there too. By doing this you can be a hero for wildlife and go home happy knowing that you are giving plovers and terns a safe place to grow up for future generations to enjoy.

Rachel Smith is a senior research associate at the San Diego Zoo Institute for Conservation Research.

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Frog Nanny

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Tending to tadpoles means carefully monitoring water quality and providing a constant supply of food.

Frog nanny is not an official job title, but it’s been my reality this year. I’m the “nanny” for some 1,176 healthy mountain yellow-legged frog (MYLF) tadpoles.  This iconic California species is one of the most endangered frogs in North America. San Diego Zoo Global has been involved in the MYLF recovery program since 2009, and captive breeding has been an important component of our efforts to re-introduce froglets into their natural habitat in the Sierra Mountains. However, with little information on MYLF life history, the care and reproduction of these frogs in captivity presents many challenges.

I have been working on this project full-time since last October. As I enter the lab and look into the 100-gallon containers holding the result of this years’ extremely productive breeding season, a feeling of excitement and nervousness comes over me. It takes about a month and a half for MYLF embryos to hatch out into free-swimming tadpoles, and in the meantime, they require daily preening. Early in the breeding season, I start my day by counting and cataloging over 1,800 embryos. Something like picking ticks off a chimpanzee, this entails cutting through the surrounding egg jelly and extracting any unfertilized or dead embryos from neighboring healthy ones. Sitting at the dissecting microscope, I examine and record what stage of development each embryo has reached every day. By the afternoon, I am all but cross-eyed. I walk around with constant images of beautifully formed black spheres in my mind’s eye. As the embryos grow and thrive, the stress of getting them through the early stage of development is taken over by concerns for stage two of tadpole rearing.

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These black specks are mountain yellow-legged frog embryos.

So what is stage two? We begin by focusing on what tadpoles need. MYLF tadpoles require cold, clean water, constant feeding, and plenty of space to grow. Like most infants, tadpoles are voracious eaters and require a constant supply of food. If too much food is offered, it accumulates in the tank, causing water quality issues. Too little food, and big brother Jake might start nibbling on his smaller sibling Fred. Cannibalism is not uncommon in amphibian species, so all I can do to stop Jake from eating his brothers and sisters is make sure I feed him enough.

Amphibian nutrition is a work in progress, and little is known of individual species’ requirements. This year, I have gone from reproductive physiologist to dietician. Researching amphibian nutrition is complicated by the specific needs of each life stage. Luckily, I have a supporting team of professional nutritionists and a wealth of knowledge and years of experience, courtesy of Brett Baldwin and David Grubaugh, amphibian/reptile keepers at the Zoo.

Controlling water quality is another daily necessity. The difference between clean and pristine can be subtle, and can affect growth and development in ways that may not be apparent until it is too late (like during metamorphosis). Armed with the HACH colorimeter DR-900, a small team of us (Nicole Gardner, senior research associate; Bryan King, research associate; me; and our weekly volunteers, Jaia Kaelberer, Janice Hale, and Jim Marsh) conduct daily screenings of the water in which our tadpoles live. Based on data we have collected on the water quality in MYLF habitat, we have specific parameters to which we can set our water standards in the lab.

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Helping to raise new generations of mountain yellow-legged frogs is challenging, but rewarding.

They say “be careful what you wish for.” This year, we wished for a handful of MYLF egg clutches to be laid and for a couple of hundred embryos to survive. Instead, we got almost 2,000 eggs! As they grow, we become faced with a new challenge—overcrowding. To my relief, the solution becomes clear; together with our partners at the US Geological Survey and the Department of Fish and Wildlife, we decide to split our bountiful cohort of tadpoles into smaller groups. At the end of May, 711 lucky tadpoles made their triumphant way back to the wild, and 400 of their brothers and sisters stayed here with us. They will be “headstarted” and returned to the wild as froglets.

Everyone involved in this project lives and loves every moment. There is nothing more satisfying than watching a life form grow and thrive under your care. This year’s breeding season has exceeded all our expectations. If we take into account that less than one percent of MYLF tadpoles are estimated to survive to metamorphosis and only an estimated 200 adults remain in the wild, everyone currently involved in this project holds the key to this species’ survival. That can be stressful, but it is also a humbling honor. I am happy to speculate that this is going to be a good year for our MYLF program, and that I will have the chance to be part of their journey back to nature.

Natalie Calatayud is a research associate at the San Diego Zoo Institute for Conservation Research. Read her previous blog, Rocky Mountain High: Boreal Toads Going to a Place They’ve Never Been Before.

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Condor Chick: Getting Big!

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There she grows! Antiki is feathering out nicely.

Antiki, our California condor chick featured on this year’s San Diego Zoo Safari Park’s Condor Cam, is now over 100 days old and starting to get her “big bird” feathers! As many of our regular viewers have noticed, her flight feathers are growing in. Some of the first feathers that start to grow are the wing feathers. It is easy to see the feathers growing through the chick’s down—the down feathers are gray, but the new flight feathers are black. The long feathers that grow from the tip of the wing are called “primary feathers” and the feathers from the wrist to the armpit are “secondary feathers.” Primary and secondary feathers are the giant feathers that make the California condor’s wing so large and impressive; an adult can have a wingspan of up to 9 ½ feet! We are estimating our chick’s wingspan to be around 5 feet right now—between the size of a red-tailed hawk’s and a bald eagle’s. Her tail feathers are also starting to grow. They’re a little harder to see on camera, but you should be able to spot them soon.

After the wing and tail feathers fill in, the feathers on the chick’s back will start to grow, as well as the small feathers on the top of the wing (called “coverts”). Even though many new, black feathers will be covering parts of her body, she will still have lots of gray down showing, making it easy to differentiate her from her parents. Eventually, her light-colored skin will turn dark grey or black and be covered with fine, fuzzy feathers, but this won’t happen until well after she leaves the nest. Her skin will stay dark until she reaches maturity at 6 years and it turns pink-orange, just like her parents’, Sisquoc and Shatash.

The chick had her second health exam on June 25 during which our veterinary staff were able to administer her second, and final, West Nile virus inoculation. A blood sample was obtained and she weighed in at 13 pounds, 7 ounces (6.1 kilograms), over half of her projected adult weight. Even though our little girl is getting big, she still has room to grow!

The adult condors normally are fed four days per week. The other three days of the week, they are fasted. They often will not eat every day in the wild, sometimes fasting for up to two weeks, so our nutritionists recommend not feeding them every day to prevent obesity and food waste. Their diet, depending on the day, can consist of rats, rabbits, trout, beef spleen, or ground meat. We offer two to three pounds of food per bird per feeding day. When the condors are raising a chick, in addition to their normal diet, we offer extra food every day: 1 rat, 1.5 pounds of beef spleen, 1 trout, and half a pound of ground meat. They don’t end up feeding all of this food to the chick, but we want to be sure that they have enough for the growing baby. It’s difficult to calculate exactly how much food the chick is eating each day, but we estimate that she could be eating 1.5-2.5 pounds of food per day.

Many Condor Cam viewers have seen some rough-looking interactions between the chick and her parents. What may have been happening was a form of discipline. As the chick has gotten bigger, her begging displays and efforts have gotten more vigorous. These efforts can sometimes be bothersome or problematic for parents that just want some peace and quiet. The parents have two ways to make sure that the chick does not cause too much trouble while begging. They can leave immediately after providing food, which is what we’ve seen a lot of on Condor Cam; or they can discipline the unruly chick. This discipline can come in the form of the parent sitting or standing on the chick, or the parent may nip or tug at it. Either of these behaviors results in the chick being put in its place by the dominant bird in the nest, thus ending the undesired behavior. Sometimes, this discipline may occur before the chick acts up. Be mindful that this is perfectly normal for condors to do, even though it would be cruel for us to treat our own babies like that! When condors fledge, or leave the nest, they need to know how to interact with dominant birds at a feeding or roost site. This seemingly rough behavior from the parents will benefit the chick later when it encounters a big, unrelated bird that might not be as gentle.

There have been many questions regarding the chick being able to jump up on the nest box barrier. She hasn’t jumped up yet, but she may soon. Stay tuned for our next blog that will discuss this next big milestone!

Ron Webb is a senior keeper at the San Diego Zoo Safari Park. Read his previous blog, Say Hello to Antiki!

2

No Ligers Here

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San Diego Zoo Global is dedicated to helping to preserve—physically and genetically—endangered species like these Malayan tigers.

“What are you drawing?”

“A liger.”

“What’s a liger?”

“It’s pretty much my favorite animal. It’s like a lion and a tiger mixed…bred for its skills in magic.”

Napoleon Dynamite

I began working for the San Diego Zoo Institute for Conservation Research in the Reproductive Physiology department in 2003. After about a year, I noticed the most commonly asked question from kids touring the lab was: “Do you make ligers here?” I think we can thank the hit movie Napoleon Dynamite for that, but as the years have gone by, the question still arises often in many different forms. I think we all are fascinated to hear about animal hybrids—the mixing of two animals of different breeds, species, or genera—but what do hybrids mean to conservation and why do we not use our advanced reproductive technologies to create them in the lab?

There are many types of hybrids that exist such as intrasubpecific hybrids between two animals of different subspecies (like Bengal and Siberian tigers), interspecific hybrids between two animals from different species (for example, lions and tigers, resulting in a “liger” or “tigon”), and intergenic hybrids between animals of different genera (as happens when sheep and goats breed, resulting in a “geep” or “shoat”). While hybridization is often thought of as a man-made phenomenon, natural hybridization does occur. Most of us are familiar with mules, which are the product of a female horse mated with a male donkey. Mules are prized for their great strength and endurance, but all male mules and most female mules are incapable of producing offspring. This is common in hybrids because their genetic material is not perfectly matched. There is also a hybrid animal called the beefalo (prized for its meat) that is the offspring of a North American bison and a cow.

Those last two examples are domestic animal hybrids that possess traits valued by humans, yet there are many issues that occur when non-domestic animals hybridize. Wild animals have evolved over millions of years through natural selection, a process that increases the probability of survival and reproduction. Hybridization, however, can result in the loss of a morphological or behavioral trait that may be necessary for survival.

An example of this is when a mule deer that uses a “stotting” escape strategy breeds with a white-tailed deer, which employs a galloping escape strategy. The hybrid offspring inherits a slow and inefficient gait, making it vulnerable to predation. And in cases where domestic cats that have gone feral breed with wild cats, the offspring are not as genetically strong and this can affect their resistance to disease.
As climate changes occur and humans modify animal habitats, wild hybridization may become common. One such example is the “grolar bear”—the offspring of a grizzly and polar bear—that was seen in Canada. This hybrid could occur more frequently as polar bears, driven from their typical range due to melting sea ice, spend more time in grizzly territory.

If hybridization sometimes seems to create a more “fit” animal or occurs in the wild occasionally, why don’t we use our laboratory skills to create them? We have the ability to inseminate the egg of one animal with sperm from another closely related species and grow an embryo that could be placed into a host female of either species. But we don’t, simply because San Diego Zoo Global’s mission is to save species worldwide by combining our expertise in animal care and conservation science with our dedication to inspiring passion for nature. We are in the business of saving species not creating new ones.

There are exceptions to this rule, such as when a population becomes so small that it can no longer sustain itself. In this case, scientists may agree that hybridization with a closely related subspecies is the only chance for survival. This has been attempted with the Columbia Basin pygmy rabbit and its close cousin, the Idaho pygmy rabbit. The Florida panther population was brought back from the brink of extinction by releasing female Texas cougars into the habitat for hybridization—the result was a three-fold increase in the number of Florida panthers, and the hybrid offspring were genetically healthy, stronger, and longer-lived.

So, I am afraid you will not see any ligers or grolar bears being created in our lab but that is because we are working hard to help tigers, lions, polar bears, and grizzly bears maintain or grow their populations. We think they are pretty amazing just the way they have evolved.

Nicole Ravida is a research laboratory technician at the San Diego Zoo Institute for Conservation Research. Read her previous blog, No Scientist is an Island.