Animal Life in the Yosemite
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THE AMPHIBIANS

WESTERN SPADE-FOOT TOAD. Scaphiopus hammondii hammondii Baird

Field characters.—Total length 2-1/2 inches or less; hind foot with a black sharp-edged, cutting "spade" on inner margin of the smooth sole (pl. 60c.); pupil of eye vertically elliptical in outline. Coloration above light gray with irregular small markings of dark gray or black; under surface of body plain yellowish.

Occurrence.—Moderately common east of Sierra Nevada in vicinity of Mono Lake. Lives below ground in sandy situations, coming forth at night and during rainstorms.

The Western Spade-foot Toad occurs in some numbers in the vicinity of Mono Lake, but as no especial search was made for it we have only a few specimens to record. On July 22, 1915, near the southwestern shore of Mono Lake, one individual was captured as it hopped out of a hole in the sand during a thunder storm. In the season of 1916 the species came first to attention on May 5 when two individuals were captured in "auto-baited" mouse traps set in a meadow near Williams Butte. The traps were so placed that the toads could not have blundered into them, so it seems likely that they were attracted by the special scent on the traps. On May 8 another individual was obtained at the same locality. Two more were obtained in traps set toward the lake from Mono Mills, on June 20, 1916.

The Western Spade-foot Toad is even more reclusive than the ordinary toads (Bufo) and frequently escapes observation entirely, even by naturalists, in a country where it occurs in some numbers. The animals are strictly nocturnal save when rains during the summer months bring them out to spawn. They are to a considerable degree opportunists, and make use of the ephemeral rain pools as places in which to deposit their eggs. Female Spade-foots captured on May 5 and 8, and June 20, 1916, contained numbers of eggs which would have been ready to lay in the near future.



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Animal Life in the Yosemite
©1924, University of California Press
Museum of Vertebrate Zoology

grinnell/amphibians5.htm — 19-Jan-2006