YOSEMITE TOAD 659 



individuals. At Tamarack Flat, May 25, 1919, an adult female was found 

 at the base of a rotted tree stump fully 200 yards from the edge of the 

 nearest meadow and 200 feet above it in altitude, while males were heard 

 trilling in the meadow that same evening. On June 15, 1915, a chorus 

 of these toads was heard near Peregoy Meadow, although egg laying had 

 been accomplished some time previously. At Snow Flat on June 28, 1915, 

 and near Ragged Peak on July 9, 1915, other toads were heard in song. 

 At the head of Lyell Caiion on July 16, 1915, numbers of Yosemite Toads 

 were found in a small pond, and some at least of the females were engaged 

 in laying their eggs. 



On May 20, 1919, numbers of male Yosemite Toads were congregated 

 in the wet meadows on either side of the ridge east of Chinquapin. During 

 the preceding winter gophers from the adjacent slopes had moved down 

 and occupied the grassy meadows, but with the spring break-up and 

 melting of the snow the place had become untenable for the gophers, who 

 had moved up onto the hillsides once more. Their tunnel systems were 

 left as subterranean 'pipes' which carried off much of the water from the 

 melting snow banks to the creek in the bottom of the caiion. These gopher 

 tunnels served also as shelters for the toads. The latter when partially 

 hidden in the entrances to the tunnels or even when they sat quietly on 

 the open grassland were quite invisible to our eyes, so well did their pattern 

 of coloration match the greens and browns of the meadow. 



The mating song of the Yosemite Toad is a sustained series of ten to 

 twenty or more rapidly uttered notes, constituting a ' trill, ' and the whole 

 song is repeated at frequent intervals. The notes, though mellow in char- 

 acter, carry well considering the size of the animal and have a ventriloquial 

 quality which makes it difficult to locate any one animal by sound alone. 

 When a number of males are giving their songs in the same place the songs 

 overlap one another so that the general chorus is continuous. There is 

 some difference in the pitch at which the several members of a group sing, 

 varying perhaps with the size of the individual toad. The general effect 

 of a chorus is rendered more pleasing to our ears by these variations, while 

 the ensemble is even sleep-inducing in effect, as we can testify from experi- 

 ence. The notes recall the courting song of the Texas Nighthawk. 



If a person walks out onto a meadow where toads (Bufo) and tree- 

 toads (Hyla) are both 'singing,' the chorus soon comes to an abrupt termi- 

 nation. If he stands stock still for a while the Hylas will resume, but the 

 Bufos do not ordinarily begin again until the intruder has quitted the 

 vicinity. The animals probably get first knoAvledge of the approach of a 

 person by the vibrations which his footfalls produce in the ground, and, 

 as the water-logged ground in a meadow readily transmits such vibrations, 

 the toads are on their guard long before the observer can get within sight 

 of them. 



