The Herps of Catalina Island
Catalina Island Conservancy
Generally it’s the iconic bison standing on a Catalina hilltop or the site of an eagle soaring high overhead that interests people living on and visiting Catalina. Recently though, the things that slither and scuttle along the ground captured the attention of Catalina Island Conservancy biologists and visiting scientists. The Conservancy, along with researchers Jeanne Robertson, Ph.D., from California State University, Northridge, and Gregory Pauly, Ph.D., from the Natural History Museum of Los Angeles County, gathered and studied the Island’s herptefauna—or “herps” for short, including reptiles and amphibians. The team gathered genetic material from the animals that will be used for future research. Native to Catalina are five snakes, three lizards, one salamander and one frog. As well, two herps have been introduced to Catalina, and qualify in conservation terms as exotic invaders: the red-eared slider and the bullfrog. Snakes The southern Pacific rattlesnake (Crotalus oreganus helleri), Catalina’s only venomous reptile, adds a new segment to their rattle each time that they shed their skin. A snake can shed its skin multiple times per year, so the frequency of shedding varies between individuals. Rattle segments also can be broken off. So, the number of segments in a snake’s rattle cannot be used to determine its age in years. Another large species on Catalina is the gopher snake (Pituophis catenifer), which will often assume the classic strike pose similar to pit vipers, the venomous group to which rattlesnakes belong. This type of mimicry is a defense mechanism for the non-venomous gopher snake, and it will generally strike with a closed mouth, attempting to scare potential predators. California kingsnakes (Lampropeltis getula californiae) are essentially harmless and cannot be mistaken for any other snakes on Catalina due to their distinct black and white color pattern. They have a propensity for eating rattlesnakes and this remarkable ability to hunt and eat other snakes, even venomous ones, is how they have earned the title of “king” in their name. The ring-necked snake is a small snake that prefers moist habitats. It grows to only a foot or two long at the most. Two-striped gartersnakes (Thamnophis hammondii) are usually found in or around water. Rare on Catalina, they are of conservation concern. Gartersnakes can reach lengths of 2-3 feet. Lizards & Salamander The southern alligator lizard (Elgaria multicarinata) is also an Island native. Its very long tail can detach and then grow back. Once disconnected from the body the tail will thrash and writhe around for minutes, acting as a decoy that might distract and occupy a predator. The side-blotched lizard (Uta stansburiana) is the most abundant and regularly seen lizard on Catalina. The adult western skink (Plestiodon skiltonianus) does not have the bright blue tail that younger western skinks have. This is the only species of skink found on Catalina. The garden slender salamander (Batrachoseps major) breathes through its skin. It must live in damp conditions and only moves about on the ground during times of high humidity. Frogs The pacific chorus frog (Pseudacris regilla) can often be heard at night around the Island. It is Catalina’s only native frog. Formerly, or currently, depending on who you ask, it was called a tree frog, but is not a true tree frog. Bullfrogs (Rana catesbeiana) are not native to Catalina Island, but they are abundant in and around the reservoirs with permanent standing water. Turtles The red-eared slider (Trachemys scripta) is the only species of turtle on Catalina. It is not native to the Island and has been introduced through the release of pets or captives.