John Day Fossil Beds National Monument - Reptiles (U.S. National Park Service)

Alan St. John

A racer coils around sagebrush at twilight.

With a semi-arid climate and interspersed habitats from riparian areas, to grass/sagebrush steppe, to rocky basalt outcroppings, the John Day Fossil Beds is a prime area for many of the reptile species found in the region. On a nice morning in the summer, visitors hiking one of the monuments many trails are almost guaranteed a chance to see a southern alligator lizard or western fence lizard sunning itself before heading out to catch insects. Other lizards that may be seen include the short-horned lizard, common side-blotched lizard, or the western skink. Lizards, as are all reptiles, are ectothermic, which means they regulate their temperature by external sources as opposed to the mammals ability to do this through internal metabolism. Thus the lizard may be very sluggish on a cool morning as it waits for the sun to warm its blood and muscles up or they may be in hiding on a very hot day, thus letting the shade keep them cool. During the winter months the reptiles may hibernate, or in the case of snakes, will den up together in a rocky cave and go into an inactive torpor. Sightings of various snakes are also possible. The garter and gopher snakes or the western yellow-bellied racer use the floodplains and canyon bottoms of the 3 units on the monument. While they are typically nocturnal or night hunters, they can be found hunting after an unsuccessful night or heading for a nap after a drink from the river. Western rattlesnakes live throughout the Fossil Beds and can be dangerous, though they tend to shy away from people by heading off before they are seen. If surprised or threatened though, they will sound the hair raising rattle so common to the species. Just as the lizards are important in controlling insect numbers, the snakes play a significant role in controlling the rodent populations from expanding to the point that they degrade the habitat or have major disease outbreaks from overpopulation. Reptiles truly play a significant role in nature's list of checks and balances.