The Great Basin Spadefoot

Mar 27, 2017
Al St. John shares some interesting facts about the Great Basin spadefoot--a native to our dry sagebrush terrain with a fascinating "tool" at its disposal.

By Al St. John

Although Central Oregon's high desert doesn't seem like the kind of place where you'd find moisture-loving amphibians, there is in fact one species native to our dry sagebrush country. It's the arid-adapted Great Basin Spadefoot (Spea intermontana).  

 
Ranging in size
The "spade" on the rear foot of a Great Basin spadefoot. Photo: Al St. John.
The "spade" on the rear foot of a Great Basin spadefoot. Photo: Al St. John.
from 1.5 to 2.5 inches, this little toad's common name is derived from a dark, sharp-edged nubbin that protrudes from the heel of each rear foot. These "spades" are used to burrow rapidly backward into soil. It manages to survive in parched environments by remaining underground during dry spells--possibly two years or more when extended droughts occur. Occasionally, when folks dig a well or excavate a basement, these dinky amphibians are encountered ten to fifteen feet below the surface, where the deep dampness maintains sufficient metabolic hydration for them to survive.
 
With the arrival of spring and early summer rains, spadefoots emerge to breed in any available shallow water--seasonal rain pools, lake and stream edges, irrigation ditches, stock ponds, and even the warm, muddy water in a cow hoof print. The males quickly attract large aggregations of both sexes with their loud, monotone choruses of "whaaa, whaaa, whaaa." After hatching, the larvae develop rapidly and can transform from aquatic tadpoles to terrestrial adults in as little as two weeks or less. This allows them to be ready for existence on land before their often temporary pools of water have evaporated under the summer sun. 
 
A Great Basin spadefoot emerging from the sand after a rainstrom. Photo: Al St. John.
A Great Basin spadefoot emerging from the sand after a rainstrom. Photo: Al St. John.
The Great Basin Spadefoot inhabits sagebrush steppelands, salt-scrub deserts, and dry juniper-pine associations east of the Cascades. It is primarily active at night, with a diet consisting largely of insects. Indicative of nocturnal behavior, a spadefoot's eyes have vertical pupils, which quickly differentiates them from other Oregon toad species.  
 
The next time you're driving during a spring cloudburst on the high desert, watch the wet pavement ahead. Chances are, you'll see one or more of these hardy toads hopping purposefully across the road. 
 
Other Land Trust blog posts about amphibians:


Other blog posts by Al St. John:
 
A native Oregonian, Alan D. St. John lives in sage-scented juniper woodlands near Bend with his wife, Jan. Al is a freelance interpretive naturalist who uses writing, photography, and drawings to teach about the natural world. Specializing in herpetology, he has worked as a reptile keeper at Portland's zoological park, and conducted extensive reptile and amphibian field surveys for the Oregon Department of Fish and Wildlife, USDA Forest Service, the U. S. Department of the Interior's Bureau of Land Management, and the National Park Service. Along with authoring the books, Reptiles of the Northwest and Oregon's Dry Side: Exploring East of the Cascade Crest, his work has appeared in National Geographic, Outdoor Photographer, Ranger Rick, Natural History, Country, Nature Conservancy, The New York Times, and other periodicals.