BY Eston Ellis
Photography by Ken Bohn
Since the earliest days of the San Diego Zoo, there have been snakes—all kinds of snakes. There were local snakes first, many of which were found on site in Balboa Park during construction of the Zoo. Then came exotic snakes—from Diablo, the 23-foot-long reticulated python that arrived in 1920; to Adhira, a white monocled cobra that came to the Zoo in 2014.
Today, the San Diego Zoo has more than 250 snakes, from over 65 different species—including some very unusual ones that you might not see anywhere else. In addition to those on exhibit in the Klauber-Shaw Reptile House, Elephant Odyssey, Panda Canyon, Monkey Trails, and Reptile Walk, there are many more behind the scenes that are bred, raised, and cared for as part of the Zoo’s participation in the Association of Zoos and Aquariums’ Species Survival Plan (SSP) programs. The San Diego Zoo has bred some of the most endangered and threatened snakes in the world, helping to build assurance populations in zoos to ensure snake species’ survival and learn critical information about their natural history.
The total number of snake species worldwide is around 3,000, but that number is increasing as researchers continue to publish new findings describing new species, according to Kim Lovich, the Zoo’s curator of herpetology and ichthyology. “Our total of just over 65 different species is a tiny fraction of a truly unique and amazing taxon,” Kim said. “I believe it’s our role to help dispel some of the myths, help relieve some anxieties that folks have about snakes, and help show these animals for what they truly are: amazing, often beautiful, and uniquely adapted animals well worth our attention and preservation.”
Here are nine rarely seen snakes that you can see—right now—at the Zoo.
South American Bushmaster
How can you miss spotting a nine-foot-long snake? When it’s a viper known as the South American bushmaster Lachesis muta muta—the longest pit viper in the Western Hemisphere—you could be “standing in the middle of its wild habitat, know it is there somewhere, and yet go weeks without ever seeing one,” said Brett Baldwin, animal care manager in the Zoo’s herpetology department. Brett is the coordinator for the Species Survival Plan program for South American bushmasters and has studied this species in the wild. Cryptic coloration helps it disappear into its surroundings. And the bushmaster is not only the most elusive viper of its size—it is also the only New World viper that lays eggs.
The Zoo has two species of bushmasters: the South American bushmaster, found throughout northern South America, and the black-headed bushmaster Lachesis melanocephala, which has a limited range within southeastern Costa Rica. Only two zoos in the United States have black-headed bushmasters, and the San Diego Zoo is the only one to have both a male and a female. Kim notes that San Diego Zoo Global has supported field work to help biologists gain insight into the natural history of the South American bushmaster in the wild, in an effort to help guide conservation measures for the species.
Ethiopian Mountain Adder
Until 1995, only three Ethiopian mountain adders Bitis parviocula were known to exist—and only as preserved specimens in museum collections. However, a live one was found on private property in the highlands of southwestern Ethiopia; then, eventually, nearly a dozen were brought to the US. The yellow, gold, and black snake has a distinctive look, with diamond-shaped markings and a triangular head similar to that of a rattlesnake.
“When several individuals came to the San Diego Zoo, nothing was known about them,” said Tommy Owens, lead keeper. Keepers spent time researching the natural history of the region where this species is found. They reviewed temperature, humidity, and rainfall records for the area and used this data to determine how to meet the animals’ needs. “We also used our experience with similar species, and made slight modifications to the husbandry to eventually lead to our adders reproducing,” Kim said.
Staff designed and created custom-built enclosures for breeding and raising young, with two lamps that provide varying (warm and warmer) temperatures on each side, leaf litter on the top level, and a tunnel leading to a lower retreat filled with damp moss. A plexiglass panel can slide in to separate the two sides of the enclosure, so keepers don’t have to move the snakes around during enclosure cleaning. “Ethiopian mountain adders are one of the most difficult-to-handle snakes,” Tommy said. These containers are designed to provide optimum conditions for husbandry and keeper safety.
In 2014, the Zoo had its first successful birth, and seven offspring resulted. To date, the San Diego Zoo is the only zoo in the US to have successfully bred Ethiopian mountain adders. “Several of the juvenile snakes hatched at the San Diego Zoo have gone off to be reared by colleagues at other AZA zoos. We will continue to share what we learn about the natural history and biology of these beautiful snakes, in an effort to provide the best care possible,” Kim said.
Santa Catalina Island Rattleless Rattlesnake
What’s a rattlesnake without a rattle? In the case of the Santa Catalina Island rattleless rattlesnake Crotalus catalinensis, it’s a small snake that evolved in a remote area where that built-in predator alarm system wasn’t needed. Along with the lack of a rattle, this species can have siblings of two different colors—brown and white—in the same clutch.
These snakes do not, as some people think, live on California’s Santa Catalina Island—they live on a remote island off Mexico: Isla Santa Catalina, in the Gulf of California. Because the location is rarely visited by anyone except fishermen looking for water, that remoteness has helped this uncommon species survive. However, because their total range in the wild is limited to one tiny island, maintaining a healthy assurance population in zoos is crucial. The San Diego Zoo is working with the Los Angeles Zoo on behalf of this snake, and these are the only facilities that have successfully bred this species. Drought and other extreme climate events can have huge impacts on such a small island population, so working together to learn as much as possible about this species is critical. This species is listed as Critically Endangered on the IUCN Red List and is a protected species within Mexico.
Mang Mountain Pit Viper
With its cryptic coloration of emerald green and brown, the Mang Mountain pit viper Protobothrops mangshanensis seems to disappear into the foliage of its temperate rain forest habitat, in the mountains of China’s Hunan Province—an area that gets over 90 inches of rain each year. This remote habitat is perhaps one reason this species was entirely unknown to Western science until 1989. The Mang Mountain pit viper’s wild population is estimated at only 300 to 500, and the total area of their range covers less than 18.6 miles. Deforestation, as well as habitat alteration from dam building and subsequent power line installation, has had a major impact on this species.
The San Diego Zoo’s first Mang Mountain pit viper—a pregnant female—arrived in 2002. She laid eight eggs while she was still in quarantine, waiting to go on exhibit, and they successfully hatched here. “Ten years later, those individuals grew up and mated with Mang Mountain pit vipers that arrived from Germany, laid eggs, and hatched a new generation,” Tommy said. “The first births at the Zoo (in 2002) were from a female that bred in the wild, but this most recent group was actually the result of breeding in managed care.”
This species has now been bred in Germany, China, and the US, helping to build a managed assurance colony. At the same time, researchers are learning about the species’ natural history, to help conservationists within China develop recovery plans for this species. One observation is that Mang Mountain pit vipers are most active at night. “We actually learned that during Nighttime Zoo,” Brett said, explaining that mating was observed during the Zoo’s extended evening hours during the summer. In fact, many of the Zoo’s reptile species are crepuscular—a term used for animals that are most active at dawn and dusk—so late hours are often the best times to visit the Reptile House.
A large snake, often 10 feet long or more, the Boelen’s python Morelia boeleni easily attracts a crowd at the Zoo’s Reptile House. This snake sports a distinctive black coloration that can appear blue, along with creamy yellow or white markings. This python is found only in the rugged mountain forests of New Guinea. An arboreal species, it can be found high among the orchids and other epiphytic plants that cover the branches of various rain forest trees.
Pythons and boas are often exploited for their beautiful skins, which are used in the leather trade. The growing demand for snakeskin in fashion items such as purses and handbags—and the resulting wildlife trafficking—is putting pressure on the wild snake populations. Currently, this elegant python species is believed to have stable populations in the wild, although Kim points out that deforestation is certainly a threat to this island species.
Two-striped Garter Snake
Native to Southern California and Baja California, Mexico, the two-striped garter snake Thamnophis hammondii is primarily aquatic and feeds mainly on fish and frogs. It was once common in Southern California, and many adults today can remember seeing this snake in local canyons and state parks when they were children. However, “habitat alteration and climate change will have long-term implications for this species, and it is becoming increasingly rare to see them in the wild,” Kim said. This snake is now protected as a “species of special concern” by the state of California, because of significant loss of its wetland habitat. Drought and catastrophic fires also threaten this species, and so do introduced non-native species such as bullfrogs and crayfish that prey upon this small snake.
A small group of two-striped garter snakes is on exhibit at the San Diego Zoo in Reptile Walk’s California Natives building. “We hope to learn about the husbandry and care of many of our native species of reptiles and amphibians, so that we can share this information with colleagues—such as the California Department of Fish and Wildlife and the US Geological Survey, with whom we partner on several native species conservation programs,” Kim said. “These populations can help guide recovery efforts and provide some insurance, in the event headstarting is needed.” Southern California is a biodiversity hotspot that contains many unique and threatened species like the two-striped garter snake.
Sierra del Nido Ridge-nosed Rattlesnake
The Sierra del Nido ridge-nosed rattlesnake Crotalus willardi amabilis is native to the Sierra del Nido mountains of Chihuahua, Mexico. Ridges made of upturned scales on each side of this snake’s nose give it the “ridge-nosed” name. It is an ambush hunter, feeding on small mammals, lizards, birds, and insects. This rattlesnake is small, growing to a maximum length of about two feet. It is rare in zoo collections, but the San Diego Zoo has several.
Rattlesnakes like the Del Nido ridge-nosed are often feared because of their venomous bite, but medical researchers have discovered ways to use snake venom that may ultimately save millions of lives. Hemotoxins—venom toxins that target the circulatory system and prevent blood clotting—have successfully been used to create medicines for high blood pressure and heart attacks in humans. In fact, commonly prescribed angiotensin-converting enzyme (ACE) inhibitors are formulated with a synthetic version of a snake venom protein. Research continues, and scientists are working to develop more venom-derived treatments for stroke patients, and those with diabetes and blood disorders. Researchers are also looking at new ways to use neurotoxins—venom toxins that target the central nervous system—to develop medicines for treating patients with brain injuries, Parkinson’s disease, chronic pain disorders, and Alzheimer’s disease.
Yellow-blotched Palm Pit Viper
Brilliant green yellow-blotched palm pit vipers Bothriechis aurifer are rarely seen in zoo collections. They live in northern Guatemala and the eastern Chiapas region of Mexico, at elevations of 3,000 to 10,000 feet, in a cloud forest environment with high humidity and cool temperatures. These palm pit vipers often live around bromeliads, because “These water-storing plants attract frogs and lizards, and the palm pit vipers gather there to feed on them,” Tommy said. Unfortunately, their habitat is being affected by deforestation and human development, and the yellow-blotched palm pit viper is currently listed as Vulnerable on the IUCN Red List of Threatened Species. The San Diego Zoo has been able to successfully breed this rare species.
Banded Rock Rattlesnake
The banded rock rattlesnake Crotalus lepidus klauberi lives in forests and rocky areas of southeastern Arizona, southwestern New Mexico, parts of western Texas, and throughout mountains of Central Mexico, and it is normally found at elevations of 5,500 to 8,200 feet. This 20- to 32-inch snake has distinctive dark rings separated by a few inches, and its contrasting body color can be gray, bluish, pinkish, greenish, tan, or lavender. They blend in remarkably well with the lichen-covered rocks of their habitat.
This species’ scientific name is a tribute to Laurence Klauber, former curator of reptiles and board member of the San Diego Zoo, who had a passion for rattlesnakes and eventually became the world’s foremost authority on them. A “citizen scientist,” he collected and studied rattlesnakes in his spare time while working as an engineer—and later chairman of the board and CEO—of San Diego Gas and Electric Company. His remarkable lifetime collection of rattlesnake specimens can now be seen at the San Diego Natural History Museum, where he was curator of reptiles and a member of the board of directors.
Dr. Harry Wegeforth appointed Laurence Klauber as the San Diego Zoo’s first curator of reptiles in 1921. At the San Diego Zoo, he helped create the current Reptile House, which opened in 1936, and expanded the Zoo’s reptile collection to more than 900 individual animals. He inspired numerous herpetologists and was a mentor to many, including Si Perkins and Charles Shaw, who both, at different times, worked as curator of reptiles at the San Diego Zoo.
Laurence Klauber published many articles and papers on snakes during his career, culminating in the publication of the two-volume Rattlesnakes: Their Habits, Life Histories, and Influence on Mankind in 1956—a work that is still regarded as the most comprehensive study of rattlesnakes available today. He was the first person to describe a total of 56 different reptile taxa between 1924 and 1963, and 13 reptile taxa were described and named in his honor by others.
For more than 100 years, the San Diego Zoo has been dedicated to helping threatened, endangered, and rarely seen snakes survive—both in their wild habitats and in managed care. That has resulted in some remarkable species success stories, and some remarkable snakes cared for at the Klauber-Shaw Reptile House. Next time you’re at the Zoo, be sure to look for these unusual, beautiful, and often misunderstood animals.