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Ecology

Local Reptiles and Amphibians

By Sylvia Powell

The area of eastern Washington's Columbia Basin, including the Hanford Site, is home to around a dozen reptile and amphibian species. While some reptile and amphibian species have not been observed for over a decade, others are fairly common. A lot has changed in Columbia Basin over the past several years, including the reduction of shrub-steppe habitat and an increase in agriculture and urbanization. Some wildlife populations can survive alongside human populations, while others are systematically reduced and sometimes eliminated by expanding human developments. Road traffic, wildfires and agricultural activities are common examples of potential hazards to reptile and amphibian populations. A few studies have been done to begin to understand the habitat requirements of reptile and amphibian species on the Hanford Site.


Great Basin Spadefoot

A young Great Basin spadefoot, Spea intermontana, sits after being released by researchers.


These beautiful animals are often difficult to spot because their coloration is very similar to their natural surroundings. One of the most important reasons for camouflage is to keep predators, especially birds, from seeing them. There are several birds that prey on reptiles and amphibians, including loggerhead shrikes, hawks, and great blue herons.

Reptiles and amphibians are ectothermic, meaning their body temperature is controlled by their surroundings. They lack an internal thermostat like mammals and regulate their body temperature behaviorally. For example, reptiles and amphibians will sit in the sun to raise their body temperatures; this behavior is called basking. During the hottest hours of the day, they may move into shaded areas or bury themselves to maintain proper body temperatures. Different species have different temperature needs. Some local snakes and toads are active at night when temperatures drop, and remain less active during the day to avoid extreme heat. All of the local lizards are active during the day and sleep at night.


Woodhouse's toad

A male Woodhouse's toad, Bufo woodhousii, sings at a breeding site.


The frogs of this region are limited to habitats near permanent bodies of water, such as the Columbia River, while toads also take advantage of temporary bodies of water created by the rising and falling of river levels. Amphibians need water to lay their eggs. The toads and frogs living here include native species such as the Great Basin spadefoot (Spea intermontana) and Woodhouse's toad (Bufo woodhousii), and the non-native American bullfrog (Rana catesbeiana), which is native to the eastern United States. All of these species lay eggs that hatch into tadpoles which develop in the water. Tadpoles begin life by feeding on algae and, once they metamorphose into juvenile froglets or toadlets begin to feed on insects. Adult frogs or toads feed on smaller animals, including invertebrates like insects. Most amphibians are gape-limited predators, so they cannot eat animals larger than their mouth opening. American bullfrogs and their tadpoles are relatively large and sometimes prey on other smaller amphibians. The apparent disappearance of the native northern leopard frogs, a species once seen in this area, has been attributed to the bullfrog.


gopher snake

Gopher snakes, Pituophis catenifer, exhibit a wide variety of defensive behaviors, including rattlesnake mimicry. This startled gopher snake is displaying a tensed neck and flattened head.


The snakes in this area are very different from each other. They differ both in appearance and behaviorally. Some of them have beautiful patterns that help them to remain camouflaged, such as the gopher snake (Pituophis catenifer) (also known as the bullsnake) which often lives near farm fields where rodents like mice are easy to find. The racer (Coluber constrictor) is a dark colored snake that doesn’t have a very bold pattern. The racer is a very good climber and eats a wide variety of food items including rodents, small birds, and smaller snakes and lizards. Western terrestrial garter snakes (Thamnophis sirtalis) are small and mainly eat invertebrates such as insects and worms, but occasionally eat other vertebrates like small frogs. Night snakes (Hypsiglena torquata) and striped whipsnakes (Masticophis taeniatus) have also been observed in this area. The whipsnake is a Washington State Candidate species which means its status may meet the listing criteria for State Endangered, Threatened or Sensitive.

The western rattlesnake (Crotalus viridis) belongs to a group of snakes known as pit vipers. The rattlesnake has a triangular head with pits near its nostrils. It uses the pits for sensing the heat given off by other animals. When a rattlesnake bites prey, for example a rat or mouse, the snake injects venom into the prey but the snake may not immediately capture the prey. These heat sensors allow rattlesnakes to follow the trail of bitten prey and eat prey that is dying from the venom. This hunting strategy may help rattlesnakes avoid injuries, because potential prey can bite and kick and harm snakes. The western rattlesnake has a thick body and doesn’t do much climbing. They tend to live in rocky areas where they can find refuge and good places to bask.


Racer

A racer, Coluber constrictor, rests after being released by a researcher.


Adult rattlesnakes shake the rattle at the end of their tails to let other animals know when they feel uncomfortable or threatened. If you see or hear a rattlesnake you should leave the area because they are venomous and may strike at objects with their mouth open when they are scared and inject venom through their fangs. While the western rattlesnake is the only venomous snake species in the area, other snakes can mimic rattlesnake defensive behaviors. Some non-venomous snakes, such as the local gopher snake and racer, mimic the rattlesnake’s rattle sound by rapidly hitting their tail against the ground or vegetation. Several snake species strike at objects when they are stressed or trapped. However, snakes often attempt to avoid potential predators or danger altogether by fleeing or hiding.

The lizards of this region include the pygmy short-horned lizard (Phrynosoma douglasii) (also known as the horny toad), northern sagebrush lizard (Sceloporus graciosus) and the common side-blotched lizard (Uta stansburiana). All of the lizards eat invertebrates such as insects and spiders. Like other reptiles and amphibians, lizards are not very active when it is cold outside. Lizards become active in March or April and are seen with less frequency once it gets cold in the autumn. Little is known about winter hibernacula, but hibernation is assumed to occur underground or in rock or debris piles where temperatures are more stable. The common side-blotched lizard has been known to come out to bask in the open on warm days in the middle of winter. This lizard is fast and it is the one which ecologists on Hanford see most frequently, possibly because it flourishes in edge habitat, such as near roads where it can catch insects in the open and retreat to vegetation for cover.


A side blotched lizard, Uta stansburiana, showing it's beautiful colors on the hot sunny day.


The northern sagebrush lizard is found frequently in areas with shrubs, such as sagebrush, and bunchgrasses. Sometimes this lizard sits in shrubs. The northern sagebrush lizard is a Federal Species of Concern and a Washington State Candidate Species because its habitat is diminishing. Conserving dune areas and native shrub habitat may be essential for the species to survive. Ecologists have noted that there are fewer sagebrush lizards in areas dominated by cheatgrass, a noxious non-native weed. This may be because cheatgrass forms a fairly continuous ground cover that may make it difficult for lizards to move, find food, maintain the right body temperature, or hide from predators. It is noteworthy that common side-blotched lizards and northern sagebrush lizards lay eggs that are protected underground and these eggs have specific moisture and temperature requirements. Like amphibians, the places where reptile populations may survive could be limited by where their eggs can survive.


horny toad

A pygmy short-horned lizard, Phrynosoma douglasii, basks in the sun on a spring day.


The pygmy short-horned lizard or horny toad is slower moving compared to the other two species and it looks much different. The pygmy short- horned lizard can live at slightly higher elevations. It has been observed in undisturbed habitat on Rattlesnake Mountain as well as at lower elevations with taller vegetation. The short-horned lizard are live bearers, which means the eggs remain inside the female lizards until hatching time. Garter snakes and rattlesnakes are the only other live bearing reptiles in this area. This lizard has only been observed a handful of times on Hanford and very little is known about its status in our area.

There are more reptiles and amphibians living in our region but even less is known about their survival strategies. For example, tiger salamanders (Ambystoma tigrinum) have been found near the Columbia River but we do not know whether this a native population or if they were introduced by people using them as fishing bait. Western painted turtles (Chrysemys picta) have been seen by ecologists, but it is not known if they were released by people or if there is a breeding population in the area. There is so much to learn about the reptiles and amphibians here and ecologists are just starting to unravel some of the mysteries of how the local reptiles and amphibians survive. If you see a reptile or amphibian you can report your observation by submitting information to the Washington Herp Atlas.

--info from personal observation, communication with Ecology Group staff, and
Hallock, L. A. (1998). Herpetofauna of the Hanford Nuclear Reservation, Grant, Franklin and Benton Counties, Washington. The Nature Conservancy. Seattle, WA. [pdf]

American Bullfrog

An adult American bullfrog, Rana catesbeiana, sits in shallow water.

western rattlesnake

A Western rattlesnake, Crotalus viridis, exhibits a defensive neck posture.

Ecology

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