Animal Life in the Yosemite
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CALIFORNIA TOAD. Bufo boreas halophilus Baird and Girard43

Field characters.—Size large, adult females being 4-5 inches long (males 3-1/2 inches or less); skin rough with numerous large 'warts' (pl. 60a); a large raised gland (parotoid) on each shoulder behind ear region; space between the two glands broader than width of one gland; pupil round. Upper surface grayish green, with numerous large irregular spots or streaks of black; a conspicuous streak of white extends along middle of head and back; under surface dull yellow, sometimes with numerous small black spots. Voice: A rather deep-toned prolonged trilling, with rhythm slow.

Occurrence.—Common resident in western part of Yosemite region, below 4500 feet altitude. Recorded from Yosemite Valley westward to Snelling and Lagrange. Lives in sheltered situations on or below ground, coming forth at dusk of evening. Solitary except at spawning time.

43A closely related subspecies, the Northwestern Toad, Bufo boreas boreas Baird and Girard, occurs at Walker Lake and near Williams Butte. It is distinguished from the California Toad by darker coloration and by having the spread of the hind foot (from tip of first toe to tip of fifth toe) more than 36 per cent of body length. The habits of the two subspecies are alike, so far as known.

The California Toad is common in the lowland and foothill territory in the western part of the Yosemite region, and upon two occasions it was found on the floor of Yosemite Valley. Its range is separated from that of the Yosemite Toad by a considerable altitudinal interval, involving the upper two-thirds of the Transition Zone. East of the mountains is found a close relative, the Northwestern Toad.

The California Toad, and toads in general (of the genus Bufo), may be distinguished from other tail-less amphibians of the Yosemite region by the presence of a large raised area, the parotoid gland, on each 'shoulder' behind the ear membrane (pl. 60a). The Spade-foot (Scaphiopus) may show a slight elevation in the same region, but that animal may be recognized otherwise by its cutting 'spade' on the hind foot and by the elliptical pupil in the eye. True toads (Bufo) have the pupil circular. The California and Northwestern toads have the parotoid glands rather long and widely separated, whereas the Yosemite Toad has these glands but little longer than broad and separated by about the width of one of the glands. Locality will serve to distinguish the California and Northwestern toads, the former occurring only on the west slope of the mountains and the latter, so far as the Yosemite section is concerned, exclusively on the east side.

At most localities in the western foothills we found the California Toad exceedingly abundant, probably in about the same numbers as were present before the country was settled by the white man. In most settled districts toads have suffered great decrease from one cause or another incident to man's activities. Early in the morning the soft dust of roadways was often closely patterned with tracks where the toads had been traveling about during the preceding evening. At Pleasant Valley count was kept on the evening of May 28, 1915, of the toads seen along a certain quarter-mile of dusty road which passed between a hayfield and an open pasture. At 7:40 P.M., in early twilight, nine were counted; upon returning at 8:00 P.M., when the light of day was practically gone, thirteen toads were checked off.

The California Toad is such a heavy-bodied animal that it seldom hops in the conventional manner in which toads are supposed to move. When not frightened it walks in slow fashion, dragging the hind feet so that the toes are continually in contact with the ground. The 'track' consists of a series of distinct little pits, 5 in number, indicating the positions of the toes when the foot is against the ground, and the successive series of dots are connected by faint grooves where the toes have been dragged along in the dust.

The difference in size between females and males is marked in this species. Females are decidedly larger and more heavily built, and during the breeding season their skin remains rough, whereas that of the males then becomes quite smooth. The males, during the breeding season at least, have developed on the 'thumb' and inner sides of two adjacent 'fingers' areas of rough dark-colored skin, which in combination with their smaller size makes possible easy distinguishment of the sexes.

In the late spring months the toads betake themselves to pools of water for the purpose of laying eggs. The spawning season had practically passed when our field party arrived at Pleasant Valley in May, 1915. One animal was noted croaking in the water of Piney Creek on May 22, and on May 23 the small black tadpoles of this species were noticed in a small creek near Forty-nine Gap. A majority of the toads taken on these dates had already deposited their eggs. A few of the females—and they were the largest of all, measuring 4 inches or more in length—had not laid their complement of eggs. Whether there is a differential laying, with the smaller animals coming first, is not known. Males were encountered in smaller numbers than females, and some at least of the former had already lost the dark horny patches on their 'fingers.'

On several occasions during the hot days of early summer, California Toads were observed at the entrances to burrows of meadow mice and ground squirrels. The toads probably make pretty general use of such burrows as daytime retreats, going greater or less distances below the surface as may be necessary to escape the heat and dryness of the mid-day hours.


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

grinnell/amphibians6.htm — 19-Jan-2006