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Field Guide



Michael Wall, Ph.D.
Director of the Biodiversity Research Center of the Californias

Red Diamond Rattlesnake (Crotalus ruber)
Red Diamond Rattlesnake (Crotalus ruber)

Snakes in the Urban Interface

Bradford D. Hollingsworth, Ph.D., Curator of Herpetology

Many people react to snakes with fear and loathing, seeing them as monsters with fangs and full of ill intent. Snakes stir many powerful emotions in us, yet monsters they are not. Snakes are secretive animals, preferring to remain hidden. They often travel at night, and do not seek out encounters with people. In fact, snakes remain some of the most poorly understood animals in the world today. Without a better understanding, many people may still view them as monsters.

Ring-necked Snake (Diadophis punctatuc)
Ring-necked Snake
(Diadophis punctatuc)

In backyards across San Diego, encounters with snakes will become more frequent as days get longer and the months get warmer. The urban interface is expanding and housing construction is pressing outward. Houses that border the natural vegetation also border habitat that is crucial to maintain the regionís high biodiversity. In these areas, snake encounters can be recurrent.

Most encounters involve finding snakes crawling through backyards or their discovery in hidden retreats. The diminutive Ring-necked Snake often turns up in gardens when rocks are moved or overturned. Larger species make bigger impressions. Gophersnakes are a common species in the urban interface. Despite their impressive size and fearsome disposition, this species should not be considered dangerous. In fact, snakes play an important ecological role by controlling abundant rodent populations.

Rosy Boa (Lichanura trivirgata)
Rosy Boa (Lichanura trivirgata)

In San Diego, there are 25 species of snakes. Little is known about their ecology and even less about their behavior and movements. However, a new technology involving the innovation of radiotelemetry is allowing us to learn more. These studies utilize implanted transmitters that send back information on location, movement, and temperature. Dr. Tracey Brown, professor at CSU San Marcos and a Museum Research Associate, studies the ecology of the Red Diamond Rattlesnake using radiotelemetry. For the first time, implanted transmitters are sending back information on home range sizes, patterns of movements, and preferred activity temperatures.

Other radiotelemetry studies are shedding light on one the regionís most secretive snakes, the Rosy Boa. Dustin Wood from the USGS and a Museum Department Associate has studied the spatial ecology of the Rosy Boa. Over time, he saw patterns of movement fluctuate and home range sizes expand as the males seek out females.

These studies bring us a better understanding about snakes and the reasons they are encountered. As more information about the snakesí behavior is gathered, their secrets are discovered. Backyards constructed within home ranges, in time, will see snakes traversing through them. As their mysteries are revealed, our preconceptions should change. Understanding that it is the fence that is trespassing in the snakeís established home range should give us more tolerance for the intrusion.

Learn more about snakes in San Diego County. Visit the Museum's online Field Guide section on snakes.