Reptiles and Amphibians

Reptiles and Amphibians

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Drought: Reptiles Don’t Like It, Either!

A cell phone photo taken of the habitat at the Safari Park Reserve in August 2014 shows just how devastating the drought has been on our local habitats.

A cell phone photo taken of the habitat at the Safari Park Reserve in August 2014 shows just how devastating the drought has been on our local habitats.

The drought has been awful for Southern California residents: dry, hot days, water restrictions, and a brown landscape. These are things we can all live with, but for our resident native reptiles and amphibians, drought can be a life-or-death situation. I have been working in the San Diego Zoo Safari Park’s Biodiversity Reserve (a 900-acre area adjacent to the Safari Park) for 15 years studying the reptile and amphibian species that call it home. This year I began a project studying a relatively rare coastal sage scrub species, the coastal patch-nosed snake Salvadora hexalepis virgultea. My plan was to capture at least 10 animals and implant them with radio transmitters so I could follow their movements and study their ecology. On normal rainfall years I see an average of eight of these wonderful snakes, so I figured that if I actively searched for them, I would be able to get a good sample size to study. However, I did not count on the drought being so intense.

Snakes get most of their water from the food they eat, and when there is no water, the food disappears as well. Many of our small, native animals tend to stay underground during such “tough times” and await better weather. Not only did many of the prey species disappear over the spring and summer, but the snakes also stayed deep underground to conserve moisture. Some snakes and other reptiles came to the surface for a brief period during the breeding season (April through June), and I was able to find a couple of patch-nosed snakes for my study. Unfortunately, reptile activity ceased altogether soon after. On a good spring day in a year with normal rainfall, I can find up to 20 snakes belonging to 8 to 10 different species in a single day. This year, in stark contrast to normal expectations, my best snake day yielded just two snakes. In addition, I spent nearly every day in the field for seven weeks in May and June and only saw two rattlesnakes. As the summer progressed and the habitat became more and more dry, very little lizard and snake activity was observed.

A red diamond rattlesnake found during a cover board array survey in 2010 at the Safari Park Biodiversity Reserve shows how lush and green the hills were that year.

A red diamond rattlesnake found during a cover board array survey in 2010 at the Safari Park Biodiversity Reserve shows how lush and green the hills were that year.

August is often our driest month, so we rarely see many animals in the field at that time. We often wait until late September before we start seeing hatchlings and juveniles along with occasional adult animals. This year, the young snakes have been virtually nonexistent, and that makes sense. If the adult female snakes and lizards cannot gain enough body mass, they generally will not reproduce. Since most of our wild animals stayed underground for much of the year, they probably did not feed and therefore were unsuccessful in breeding.

Last week I saw firsthand how difficult the drought has been on our native snakes. While walking through the coastal sage, I found a large, female red diamond rattlesnake Crotalus ruber. She was very thin and could barely move. I presume she had recently given birth (rattlesnakes in San Diego County give birth to live young in August and September) and just did not have enough body mass to make it through her pregnancy. No baby snakes were found in the vicinity, and I can only hope this female pulls through. If she had babies, they will, hopefully, be able to hold out until the rains eventually arrive.

A cell phone photo shows an emaciated red-diamond rattlesnake at the Reserve in September, 2014. Many of our local reptiles and amphibians are suffering from the recent drought.

A cell phone photo shows an emaciated red-diamond rattlesnake at the Reserve in September, 2014. Many of our local reptiles and amphibians are suffering from the recent drought.

In over 30 years of field “herping” (searching for reptiles and amphibians), I have not experienced drought conditions worse than those seen in 2013 and 2014. In fact, the North American Field Herping Association has shown just how bad the drought has been on Southern California snakes. When comparing non-drought year data from July 1, 2010, to June 30, 2012, with drought year data from July 1, 2012, to June 30, 2014, for snakes found in Los Angeles, San Diego, Orange, San Bernardino and Riverside counties, 4,971 snakes (1,055 hatchlings) were found between 2010 and 2012 whereas only 2,888 snakes (680 hatchlings) were found from 2012 to 2014. It is also interesting to note that there were more contributors to the database in the latter years, so roughly half the snakes were found by considerably more field herpers in the drought years than in the normal rainfall years, and roughly half the hatchling snakes were found in the drought years than in the normal years.

Here's a portrait of a healthy long-nosed snake in the Safari Park Biodiversity Reserve in 2009.

Here’s a portrait of a healthy long-nosed snake in the Safari Park Biodiversity Reserve in 2009.

So what does this all mean? Nobody can be certain right now. We do know that our climate has boom and bust years and drought and rainfall totals are very cyclical for most areas of the world. However, our findings to date do suggest that climate change is occurring at a rapid pace, and we all need to do our part to protect the environment and our natural resources, especially the snakes!

Jeff Lemm is a senior research coordinator in the Behavioral Ecology Division of the San Diego Zoo Institute for Conservation Research.

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Catching Rock Iguanas: Easier Said than Done!

Corinne PisacaneThis year I traveled to the Turks and Caicos Islands to study wild rock iguanas. The Turks and Caicos rock iguana Cyclura carinata is endemic to this Caribbean country and is critically endangered. Our team flew to the island of Providenciales, the main hub for tourist travel. From there we continued in a much smaller plane across the beautiful and shallow waters of the Caicos Bank to our final destination, Big Ambergris Cay. This island, located about 40 miles east of Providenciales, is diminutive in size, measuring about 4 miles (6 kilometers) long and only 1 mile (1.6 kilometers) wide. Its highest point is less than 100 feet (30 meters) above sea level. In addition to the iguanas, this secluded island hosts a number of private residences, and there are plans for a large housing development, which poses a potential threat to iguana habitat on the island.

During my time on Big Ambergris Cay, I was involved with a graduate student’s dissertation project involving iguana capture, relocation, and the subsequent examination of homing abilities (among a number of other iguana-related activities!). Every day we set out after it warmed up enough for iguanas to come out of their nooks and holes. Once we located individuals of interest, we set about stalking them. A number of our team members then attempted to catch iguanas of interest with varying degrees of success. Sometimes the lizards were just too fast and would elude our attempts with ease!

Once caught, our next challenge was to try to take a blood sample from each iguana to measure baseline stress hormones. From the moment we caught each iguana, we had exactly three minutes to successfully collect the blood. Any time over three minutes meant that stress hormones (or glucocorticoids) had already reached the iguana’s circulation, meaning we were measuring its stress response to the capture, which was not our goal. As you can imagine, this made for a very exciting three minutes!

If we were not successful, the iguana would be released and not considered as part of the study. If we did succeed, the iguana was then numbered using a system of color-coded beads strung through Spectra line and placed on both sides of the iguana’s dorsal crest between the shoulder blades. This dorsal skin is similar to that of our earlobes, and the stringing of the beads is thought to feel much like piercing one’s ears. Once we were finished marking individuals with beads, each iguana was also fitted with a small radio transmitter to enable future tracking of their movements on the island.

After the identification beads and radio transmitter were secured, iguanas were released at their point of capture and tracked for two weeks to determine their home range. Then they were recaptured and relocated to a different study site just under a mile away to determine if relocation might be used to successfully mitigate future development. As soon as they were released, the race was on! Equipped with radio-receiver equipment, researchers tracked the movements of the iguanas daily to investigate where they went. It appears that adult iguanas can usually find their way home, although how they do so is still not fully understood. By contrast, the homing skills of juvenile iguanas don’t appear to be as developed, and they usually stay put in their new home. For this reason, juvenile iguanas make better candidates for relocation than adults.

Alongside all the capturing and relocating of iguanas, our team also processed all the blood samples collected. This was no small task, as the logistics of processing blood on a small Caribbean island are very involved and time sensitive. Samples had to be frozen immediately, which required transferring them from a portable mobile cooler, carried by each researcher, to a larger cooler on a golf cart (the only mode of transportation around the island!) and then, finally, back to one of our rooms where we’d set up a mobile laboratory. Overall, this was quite an operation! Picture at least half of a dorm room set up as a temporary lab with collection tubes, a centrifuge, slide-staining equipment, and blood-draw needles.

Having traveled to a number of tropical places, I had expected the Turks and Caicos landscape to be all soft sand and friendly flora, with iguanas living in a beach environment. How wrong I was! All this capturing, relocating, and tracking takes place on volcanic-like ground that can quickly tear up ordinary shoes. The ground is also uneven and makes capture and tracking a slow and strenuous process. In addition, the small shrubs and trees are full of thorns and are quite abrasive. As a result, we always wore long pants and covered up at all times, making the work more challenging as it got extremely hot outside. Thick-soled shoes were also critical if we were to move around quickly enough to capture iguanas and avoid large thorns entering the soles of our feet. While we find it difficult to deal with this kind of environment, the iguanas have evolved to be perfectly suited to it.

This type of research is critical to gain a thorough understanding of the biology and behavior of the Turks and Caicos rock iguana. As with most endangered species, we need to be diligent about setting aside the necessary habitat for these amazing reptiles. Rock iguanas throughout the Caribbean are in danger of losing their habitat as a result of human-related pressures. I learned a great deal while on Big Ambergris Cay and am very grateful that I could be involved with iguana conservation in such an amazing habitat!

Corinne Pisacane is a senior research technician for the San Diego Zoo Institute for Conservation Research. Read her previous post, ISWE: Cheetah Pseudopregnancy?

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7 Animal Facts You Didn’t Learn In School

You don’t have to be an animal expert to appreciate the natural world. In fact, simple short cuts like the fun facts listed below, can be very conducive to gaining a better understanding of the Animal Kingdom. Enjoy!

Monkeys have tails and apes don't.

1. Monkeys have tails and apes don’t.
Since we have more in common with our great ape cousins than we do with monkeys, a good way to remember this fact is to simply look at your rear end.

There’s no such thing as a poisonous snake.

2. There’s no such thing as a poisonous snake.
Contrary to pop culture and older versions of Encyclopedia Britannica, snakes are venomous, not poisonous. If they were poisonous, touching or licking a serpent would be the more appropriate fear than death by snakebite. And that’s even debatable, since statistics show that out of 7,000 to 8,000 snakebites per year in the U.S., only 5 or 6 are fatal. Call it semantics, but the truth is only 10 percent of the 3,000 species of snake are venomous, meaning they inject toxins into their prey (biting or stinging). The difference is skin deep.

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The World for a Desert Tortoise

Tortoise Montana shared some attitude with Paul.

Tortoise Montana shared some attitude with Paul.

While working at San Diego Zoo Global’s Desert Tortoise Conservation Center in Las Vegas, I have handled over a thousand desert tortoises. All of them are important to me. One function of my job is to find tortoises and bring them in for medical check-ups, evaluations, and preparation for relocation into the wild. Most desert tortoises are calm, curious, and easy to handle if you are nonthreatening. One tortoise, however, stands out among them all.

Early April. I had to go into Pen #362, find tortoise #17894, and bring her in for medical check-up. The tortoise was in an artificial burrow. I got on the ground, flipped on my flashlight, and prepared for the rough work of trying to coerce a well-dug-in tortoise to come out. Suddenly, one fierce reptile charged out! She scampered all the way from the back of the burrow, legs swimming through dirt and pebbles. She ran at me as if she wanted to fight! All I could think of was Al Pacino, as Tony Montana in the movie Scarface, confronting me. She seemed to be saying “You want to mess with me!? O-kay! You think you’re tough!? O-kay!” I picked up the tortoise, her legs flailing while trying to get at me. From now on, #17984 is Tortoise Montana!

She's now more relaxed around him.

She’s now more relaxed around him.

After her check-up, she was placed back into pen #362. I fed her in the mornings, and over time she became more agreeable to my presence. By June, my route had changed and others fed Tortoise Montana, but I would occasionally go visit her whenever I could. Instead of charging out, she would calmly walk out of the burrow to come near me. Sometimes, if I had extra food, I would make a special trip to her pen to let her have it. One morning, I watched her drink from a puddle of water created by the irrigation drip system. During the heat of summer she usually slept in the back of her burrow. I asked a colleague about her status. She was healthy and would soon be translocated to the desert!

September: Translocation Week. Many tortoises were brought into the lab for their preparation. My job is to put translocation ID tags on the tortoises’ shell. I scanned the lab. There she was! A plastic box tote labeled 17894 362! I opened the tote. While sitting on her bed of hay, she was relaxed and stayed still as I applied the tag.

Paul attaches a translocation ID tag on a desert tortoise.

Paul attaches a translocation ID tag on a desert tortoise.

The next day I traveled with my colleagues out to Eldorado Valley. I knew Tortoise Montana was in the last pickup truck of our convoy. After we arrived at the release site, while gathering the tortoises, I found her tote and placed her at the front of the line for fluids. Afterward, I picked up her tote and walked into the desert with her. I eventually found a shady spot that had lots of desert flora and grass. I lifted Tortoise Montana, looked into her eyes, and gently placed her on shady ground. I filled out her data sheet, made my observations, and said “good-bye” as she looked around at her new home.

Whenever I walk by pen #362 I feel a little sad. The pen is empty now. But I feel good, too, because I know Tortoise Montana has what I know she needs: “The world…and everything in it.”

Paul Griese is a research assistant at the San Diego Zoo’s Desert Tortoise Conservation Center. Read his previous post, Burrowing Owl: Who Are You?

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Rare Frogs Holding Their Own Despite Drought Conditions

mountain yellow-legged frogA recent survey of mountain yellow-legged frogs released into the wild by San Diego Zoo Global wildlife conservationists indicates that the populations are showing signs of stress related to drought conditions in California. The juvenile frogs, released into the San Jacinto mountains in two protected sites, are representatives of a species brought to the brink of extinction by the threat of wildfire, habitat destruction and chytrid fungus. The young frogs hatched at the San Diego Zoo Institute for Conservation Research and were introduced as tadpoles into the wild in 2013.

“When we released these frogs into the wild, we knew they would be facing natural challenges to their survival, like predation,” said Frank Santana, a research coordinator with the Institute for Conservation Research. “The drought is adding an additional challenge to their survival, but we are still finding a significant number of frogs that are healthy and growing.”

Of the 300 tadpoles that were released, researchers believe about 25% continue to survive. The species is believed to number less than 200 individuals in the San Gabriel, San Bernardino and San Jacinto mountains, where they once thrived. Institute for Conservation Research conservationists, working in collaboration with government partners – U.S. Geological Survey, U.S. Forest Service, U.S. Fish and Wildlife Service, California Department of Fish and Game and University of California – are working to repopulate Southern California with these rare frogs.

CONTACT: SAN DIEGO ZOO GLOBAL PUBLIC RELATIONS, 619-685-3291

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New Generation of Rare Turtles Released into San Diego Reserve

Pond turtle releaseFive juvenile western pond turtles were released into the Sycuan Peak Ecological Reserve today by a team of federal, state and zoo scientists. The released turtles are part of the “headstart” program, which involves raising hatchlings at the San Diego Zoo to a large enough size and then releasing them into the wild, giving them a better chance of surviving and fending off natural predators.

The western pond turtles are California’s only native freshwater turtle species, a species that was once widespread in California, Oregon and Washington. They are now uncommon, especially in southern California, due to habitat loss and invasive, nonnative predators like bullfrogs and largemouth bass, which eat up the tiny hatchling turtles that are no larger than a quarter.

“Along with USGS we’re able to monitor these turtles with their radio transmitters and check on them periodically to see how they’re doing,” said Tommy Owens, senior keeper with the San Diego Zoo’s Department of Herpetology. “It’s really important here at the beginning of the release, because the turtles might not stay put and we want to be able to find them easily. Through radio tracking we can see the use of habitat, their behaviors and check on their overall well being.”

The five turtles released this morning were each fitted with a miniature radio transmitter prior to the release. Researchers attached these tiny antennae to the juvenile turtles’ shells so they can regularly check on the turtles’ growth, physical health and behavior. The transmitters were applied with a silicone sealant that allows the young turtle’s shells to grow and expand, even with the transmitter device attached to it.

Since the first generation of “headstart” turtles was released over a year ago, researchers monitoring the program have noticed progress and have been able to catch those turtles periodically to gather their measurements. After examining the turtles and checking their transmitters, researchers release them back into the same watershed.

The Sycuan Peak effort is a joint project of the U.S. Geological Survey (USGS), San Diego Zoo Global, the California Department of Fish and Wildlife (CDFW) and the San Diego Association of Governments (SANDAG). The project is testing conservation strategies to help western pond turtles and other native species, since many California ecosystems are being impacted by invasive, nonnative species accidentally or intentionally introduced by humans. The SANDAG TransNet Environmental Mitigation Program (EMP) funded the USGS’ initial work to support the restoration of the western pond turtle.

Photo taken on July 31, 2014, by Ken Bohn, San Diego Zoo.

CONTACT: SAN DIEGO ZOO GLOBAL PUBLIC RELATIONS, 619-685-3291

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Rare Night Lizards Form Satellite Population at San Diego Zoo

island night lizardA recently recovered endangered species, the island night lizard, has been added to the list of reptile species at the San Diego Zoo. Five night lizards arrived at the Zoo on July 25, 2014, brought by the U.S. Navy to be available for guest viewing. The species was removed from the endangered species list by the U.S. Fish and Wildlife Service on May 1, 2014.

“It is one of the few species that visitors to the Zoo will see that was recovered under the Endangered Species Act, and the only one estimated to occur in the millions on U.S. Navy Lands,” said Dr. Robert Lovich, senior natural resource specialist at Naval Facilities Engineering Command (NAVFAC) SW, Desert Integrated Product Team.

The island night lizard Xantusia riversiana is native to three federally owned Channel Islands (San Clemente, San Nicolas, and Santa Barbara) located off the Southern California coast, and a small islet (Sutil Island) located just southwest of Santa Barbara Island. San Clemente and San Nicolas islands, used by the U.S. Navy as training lands, are also home to several unique and endangered species that the naval command works to preserve.

“San Clemente Island is critical to the Navy’s ability to train and prepare sailors to fight in realistic situations. By adaptively managing wildlife like the island night lizard, we can conduct our mission requirements and remain great stewards of our natural resources. We’re pleased the San Diego Zoo has an opportunity to share this interesting creature with the public,” said Capt. Christopher E. Sund, commanding officer of Naval Base Coronado.

The island night lizard was placed on the endangered species list in 1977 because its habitat was threatened by feral goats, pigs and predators that had been introduced to the island. In 1992, the Navy removed the last of the feral goats and pigs from San Clemente Island and has an ongoing program to trap and remove feral cats and rats. In conjunction with these efforts, nonnative species of plants were removed from the island as well, greatly improving the habitat of the night lizards and promoting their recovery.

“Now that the species is recovered, it is important to ensure its ongoing survival by creating a satellite population away from its island home,” said Kim Lovich, curator of reptiles for the San Diego Zoo. “This satellite population provides insurance that the species will survive even in the event of a sudden natural disaster to its island home.”

The lizards will soon be available for viewing at the Zoo’s reptile house.

Photo taken on July 25, 2014, by Tammy Spratt, San Diego Zoo Global.

CONTACT: SAN DIEGO ZOO PUBLIC RELATIONS, 619-685-3291

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Volunteers Help Desert Tortoises

Volunteer Kimi Sharma won a contest for most volunteer hours worked in June: 71 hours!

Volunteer Kimi Sharma checks on a resident of the Desert Tortoise Conservation Center.

I’m always amazed to see volunteers bouncing into the Desert Tortoise Conservation Center at 5 a.m. to start the day. Most of our volunteers drive long distances to give of their time and help the tortoises. We had wonderful volunteers this season, all very dedicated! They have already put in over 600 hours so far this season!

Our volunteer coordinator, Lori Scott, did a great job coordinating, orientating, and keeping up with the various schedules of the volunteers. Lori’s job was to also make sure they felt appreciated and were gaining a valuable experience. Kimi Sharma won a contest for most volunteer hours worked in June: 71 hours! Before Kimi left to head back to school in Boston, she had acquired 155.5 hours of volunteer work. Kimi was kind enough to bring all of us lunch on her last day, which we appreciated very much…I don’t think she really wanted to leave!

The volunteers work really hard in the hot summer sun right along with staff watering, feeding, and helping us care for all the desert tortoises on site. We appreciate every hour the volunteers give of their time to help out the tortoises they care for. Volunteers help us out tremendously, and we couldn’t do our job without them!

We are now gearing up for translocation season and are always looking for volunteers to help out—it’s such an awarding experience! If you are in or going to be in the Las Vegas area and wish to help with volunteering, email us at DTCC@sandiegozoo.org.

Angie Covert is a research coordinator at the San Diego Zoo Desert Tortoise Conservation Center. Read her previous post, Internship at Desert Tortoise Conservation Center.

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Tortoise Fight

Two desert tortoises duke it out.

Two desert tortoises duke it out.

The day started in the perfectly normal manner. Hopping out of bed at 3 a.m., I cruised on through the morning schedule. Pack? Check. Water? Check. Sunblock? Check. As I walk out the door, my cat yawns and glares at me, implying “You DO know the sun’s not up yet, right?”

Once out in the field, I greet the sun rising over the Spring Mountains with the usual smile. Week after week, I track the movement of transmitter-wearing desert tortoises for the San Diego Zoo’s Desert Tortoise Conservation Center. In short, I hike a lot. However, don’t let me fool you; it’s anything but dull. That’s the beauty of working with living creatures—you never know when you’ll experience something extraordinary. And that’s just what happened that perfectly normal day in the field.

Raising my antenna, I punched the frequency for tortoise #21 into the receiver. After following the signal and tone, I finally approached #21 digging on the apron of a soil borrow. “And another one down,” I thought to myself as I kneeled down to take a GPS point. That’s when I noticed the second tortoise in the mouth of the burrow. I leaned in close, inspecting its carapace. This tortoise had been notched and tagged already, the usual procedure when we come across a resident in the field: #25. I was so caught up with identifying #25 that I hardly noticed #21’s movement until it was butting against the side of my boot. “Whoa, buddy!” Someone was clearly in a feisty mood.

I quickly finished taking my GPS point and moved away to complete the datasheet. Suddenly, I heard scuttling, scratching, and the movement of dirt coming from the direction of the tortoises. “What is going on?” I wondered, and I moved back within eyeshot of the burrow.

I froze. The tortoises were fighting! After inspecting me, #21 had proceeded to move back to the burrow and pick a fight with the larger #25. They were really going at it, their hard shells knocking together with a sharp “crack” upon contact. I initially thought I was witnessing a male versus male brawl but was surprised to discover that #21 was a female! Click on the video link below to watch…

Desert tortoise fight

Shortly thereafter, the two broke apart. I wasn’t sure if I was viewing the tortoise reenactment of “Hit the road, Jack,” but I used the pause to grab my camera in anticipation of round two. Sure enough, they collided again, pushing with their heads and the front of their shells, often lifting each other on their hind limbs due to the force. Finally, the male, #25, managed to flip the female, #21, over the edge of the burrow apron. I stopped recording and rushed to a new spot to see her. She was now on her back, but she wasn’t about to back down. She slowly righted herself on her feet, ready for round three. After several more minutes of tussling, #25 finally backed away, turned around, and moved away from the dirt burrow. Meanwhile, #21 stood triumphantly on her burrow apron watching him meander off. How’s that for a bit of spring cleaning?

I smiled, shook my head, and finished filling out the data sheet. I punched in the numbers for the frequency of the next tortoise on the list, picked up my pack, and held up the antenna.

Yep, just another perfectly normal day…

Tiffany Pereira is a research associated at the San Diego Zoo’s Desert Tortoise Conservation Center.

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Alligator Training

Xidi can be seen in the Zoo's new Reptile Walk.

Xidi can be seen in the Zoo’s new Reptile Walk.

While studying biology at the University of Massachusetts, I dedicated several years working closely with two captive, juvenile American alligators. In order for these stereotypically aggressive creatures to be utilized for classroom demonstrations, I developed a training system to make the process a little easier and, hopefully, safer! Upon my graduation, the training resulted in the alligators being able to discriminate between “attack” versus “stay” stimuli, making them a bit more predictable for the handlers.

After having a successful trial run at the University, I wanted to try similar training here at the San Diego Zoo with a female Chinese alligator named Xidi (pronounced Shee-Dee). The opportunity to begin target training on completely different alligator species is exciting! Throughout the next several months, I will be posting updates on my progression with Xidi in hopes that one day she is trained to “sit,” metaphorically, of course.

Since Xidi is a fully grown female, roughly 16 years old, I will be taking baby steps with her to challenge the cliché of not being able to teach an old dog a new trick. Previously, Xidi was fed anywhere from once a month to once a week, depending on climate conditions. Now, we will be feeding her three times a week using portion control for training progress. A dark blue circle will be used for feeding and a yellow circle for not feeding. It is unclear if alligators can discriminate colors, but they can differentiate among shades (light and dark).

Jeremy Fontaine is a keeper at the San Diego Zoo.