YELLOW-LEGGED FROGS 665 



The spawning' season of the Yellow-legged Frog varies with altitude, 

 althoug'h in each locality the adults, as a rule, probably lay their eggs 

 when the season is locally 'spring.' Thus tadpoles of considerable size 

 were seen in Blacks Creek near Coulterville on May 10, 1919, and the one 

 adult female of breeding age collected at Smith Creek on June 3, 1915, 

 had finished la^dng. An exceptional case, perhaps, was that of an adult 

 female taken near Feliciana Mountain on November 1, 1915, which con- 

 tained well developed eggs. Most of the high mountain frogs {sierrae) 

 collected at Peregoy and Mono meadows on June 22, 1915, had already 

 laid, and tadpoles were seen in some of the creeks. Some females collected 

 at and near Tuolumne Meadows during the first half of July, 1915, had 

 already deposited their eggs; others contained eggs ready to lay. 



In the foothill district, where there is a long spell of warm weather, 

 the tadpoles (subspecies hoylii) are able to grow to the size necessary for 

 transforming into frogs in a single season. But with the high mountain 

 animals (subspecies sierrae) the case is different. The eggs are not laid 

 until June or July, and there is then but a short season, scarcely three 

 months in length, before cold weather sets in again. Consequently the 

 tadpoles which hatch from the eggs in any one season go through the 

 winter still in the tadpole condition and do not transform into frogs until 

 the following summer. Thus the numbers of tadpoles, 2 inches or more 

 in length, found in Young Lake on July 8 and 9, 1915, came from eggs 

 which had been laid in 1914. On the dates mentioned many of the tadpoles 

 had the hind legs fully developed and in all probability would soon have 

 completed their metamorphosis. 



In such alpine lakes as are suited to occupancy by frogs (through the 

 absence of fish) both adults and tadpoles are usually present. The frogs 

 sit along the shore, on the ground or on rocks, whence they can reach the 

 lake at one bound. When cakes of ice are floating in the water the frogs 

 do not seem able to discriminate and in leaping lakeward they sometimes 

 land on the ice instead of in the water. Where large numbers of frogs are 

 present, a greater degree of safety is probably enjoyed by each individual, 

 for oH, of course, are on the alert, and thus the approach of any danger 

 is the sooner realized from the action of a neighbor. In spite of this con- 

 sideration, a person does not have much difficulty in capturing numbers 

 of the frogs, and it seems likely that a coyote or other carnivore would be 

 able to gather them in easily by prowling along the shore. 



When undisturbed the tadpoles rest on the sandy bottom close to the 

 shore, where the water is shallowest and warmed somewhat by the sun ; 

 but w%en frightened they wriggle off into the deeper parts of the lake. 



