Herpetological Surveys

The health of the reptile and amphibian population is studied during herp surveys.  Alligator lizards will sometimes bite their own tail to form a loop when they sense an attack, making it more difficult for a predator to attack and swallow it.

NPS Photo


The Health of Herps

For over ten years, Cabrillo National Monument has been involved in a cooperative effort to monitor the health and population status of “herps.” Park Rangers and volunteers here continue to conduct herpetological survey efforts that were initiated by the U.S. Geological Survey (USGS) and Dr. Robert Fisher in 1995. The protocol and techniques were directly adopted from the USGS in order to continue the survey effort with no loss of or change in data collection. The sampling technique and protocol are virtually identical to that described in the document “Herpetological Monitoring Using a Pitfall Trapping Design in Southern California”, USGS, 2003.

Seventeen arrays have been established and are located throughout the Point Loma Ecological Conservation Area, a cooperative land management partnership for the native habitat on the Point Loma peninsula. The Navy and the National Park Service are the predominant landowners, and arrays are scattered on these two agency’s lands to accurately capture information about species present on a variety of habitats (e.g., coastal compared to east-facing bayside habitats, sandy washes, exposed south-facing slopes, drainages, disturbed areas). The other landowners with interest in this project and members of the PLECA include the U.S. Coast Guard, the City of San Diego Wastewater Treatment Plant, and the Department of Veterans Affairs.

Sampling occurs once a month for four survey nights per session with the help of volunteers. In addition to the pitfall traps and funnel traps used for snake capture as referenced in the USGS report, boards approximately three-foot square are placed near each array arm. These are checked each day in association with the pitfall traps to check specifically for California legless lizards (Anniella pulchra) and smaller snakes.

Data is collected and recorded in the field using handheld “Palm” personal computers and associated datasheets. The forms have been developed by USGS and are the same as those used by their staff. Recording the data electronically reduces data entry error that might otherwise occur from the handwritten data forms to the computer. The data collected is directly downloaded to an Access database in the office. Data is downloaded daily and reviewed by the field technician to look for obvious errors or problems with the transfer of data from the handheld to the desk computer. HOBO® (Onset Computer Corporation) are used to collect weather data. HOBO are hand-held pieces of equipment that automatically record temperature. This information is also downloaded directly to a computer. Data is regularly forwarded to USGS for inclusion in the regional databases of records for southern California.

The USGS recently conducted a statistical review of the sampling effort. The results are summarized in the document “Sampling Design Optimization and Establishment of Baselines for Herpetofauna Arrays at the Point Loma Ecological Reserve”, USGS, 2003. After additional peer review of the results, aspects of the sampling may change slightly (e.g., removing some of the arrays). This report addressed the arrays be sampled, the number of days of sampling, and the ability of the survey to address the following questions:

  • What species are currently found at the Point Loma Ecological Conservation Area versus species that have been historically found in this area?
  • Are any of the targeted species listed showing declines at present?

Additionally, it is hoped the survey will address the question of how many arrays, sampling periods, and sampling days per sampling period would be needed to detect a

  • 30% drop in species richness
  • 30% drop in the relative abundance of orange-throated whiptail (Cnemidophorus hyperythrus) and striped races (Masticophis lateralis)
  • Some measure of drop in abundance or occupancy of western ring-necked snake (Diadophis punctatus) and southern Pacific rattlesnake (Crotalus viridis)

The cooperative efforts of the National Park Service and U.S. Geological Survey are critical in ensuring the health of “herps,” a vital part of the ecosystem on the Point Loma peninsula and at Cabrillo National Monument. Through these efforts, reptiles and amphibians will continue to be here as a part of a healthy environment and for the enjoyment of future generations of visitors.

Reptiles and Amphibians at Cabrillo National Monument

The following was written by Alicia Pinto, a recent Intern at CabrilloNational Monument and Biology student at Humbolt State University

Point Loma Herpetology Survey - The Largest Ever

In progress is a multi-year survey of reptiles and amphibians sponsored by California Fish and Game along with the University of California. The Point Loma site here at Cabrillo National Monument is among the twenty-two sites being surveyed throughout three counties in coastal southern California. The overuse of pesticides, herbicides, and other forms of human contact have diminished 95% of original coastal sage scrub vegetation. In effect, the decline in vegetation has taken a vital toll on the native reptile and amphibian habitat here at Cabrillo National Monument. This concern has driven many herpetologists - biologists studying the reptiles and amphibians - to survey the existing reptiles and amphibians within the remaining coastal sage scrub community. Our hopes are to learn who, where, when, and what is left roaming the priceless vegetation.

During a three year period, every six weeks for ten days, herpetologists and Volunteers capture, identify, log, weigh, measure, and collect DNA samples of the various herpetofauna still found at the park. Beginning July of 1995, the survey is now in its tenth year. The captures and data collected thus far are already helping herpetologists and all of us to better appreciate the role of reptiles and amphibians in Point Loma's Coastal Sage Scrub ecosystem.

Some Notes on Snakes and Lizards

If you have made it this far then you are ready - and hopefully eager - to learn more about the characteristics and habits of snakes and lizards on Point Loma. These creatures are often seen basking on a rock or tree limb soaking up the San Diego sunshine. Unlike human sun bathers who are usually lying in the sun for tanning purposes, the cold-blooded reptile absorbs the heat to keep their body temperature at a comfortable level.

Your chances of observing a California Striped Racer Snake (Masticophus lateralis lateralis) are much better than spotting a Southern Pacific rattlesnake or any other snake found at on Point Loma. This is because the racer needs daylight to see its prey. Most other snakes have poor eyesight, but the racer has excellent eyesight. A racer looks for food by lifting its head off the ground to see what prey is nearby. It also has the ability to climb trees in search for bird eggs. The California Striped Racer tends to be black on its back and soft pink on its belly. It also has two noticeable off-white, almost pale yellowish, lateral stripes running down both sides of its back. Unlike the rattlesnake, it is not venomous

A popular lizard found scurrying amongst the vegetation at Cabrillo National Monument is the orange-throated whiptail (Cnemidophorus hyperythrus). This creature has a bright orange belly and a brownish back with tan stripes extending from its head to the base of its tail. The females are less colorful than the males to keep them from being sighted by predators when carrying eggs. This particular specie has been labeled a "sensitive specie," and the U.S. Fish and Wildlife Service is proposing to list it as endangered or threatened because of its declining population.

Also seen on Point Loma is the California legless lizard (Anniella pulchra pulchra). Without legs this lizard is often mistaken for a snake. Although it is legless, it still has eyelids which snakes do not have. The lizard is restricted to California and Northern Baja California and is found no where else in the world. Along with the orange-throated whiptail, its population is declining and may be listed as endangered or threatened.

The two species of rattlesnakes found at Cabrillo National Monument are the Southern Pacific (Croatalus viridis helleri) and the Northern Red Diamond (Croatalus ruber rubber). Often heard but not seen is the sound of a rattle at the end of a rattlesnake's long body. A baby rattlesnake is born with only one rattle on its tail, but adds a new one each time it sheds its skin. After the rattlesnake has about twelve rattles, the string of rattles normally breaks off and new ones start to grow. Though rarely seen, be cautious of the possibility that a snake is present - stay on trails when visiting the park.

The Park Rangers and Volunteers encourage you to come discover a gallivanting lizard or slithering snake at Cabrillo National Monument. Many of our visitors encounter the live reptiles on the Bayside Trail. For more information once you’re here at the park, stop by the Visitor Center and pick up a Natural History Checklist.

Last updated: February 27, 2015

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1800 Cabrillo Memorial Drive
San Diego, CA 92106


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