detritus. As the species grows older, it changes its diet to animal tissue which must be swallowed whole because the frog's jaw is structured on a hinge joint that does not allow for sideways movement as in humans. Adult frogs eat a range of foods such as moths, ants, grasshoppers, hornets, beetles, flies, water striders, and snails. Mating habits The mating "ceremonies" begin in spring, when adult frogs congregate on sandy and/or rocky bars to mate. Previously believed to mate from March to May, recent experiments have shown the time to be closer to April to late June. High stream velocities, however, may dislodge R. boylii egg masses from oviposition substrates. Thus, R. boylii avoids rapid waters to protect the egg masses from being swept away. This technique is why the species has a long breeding season. If the conditions do not meet their standards, they refuse to mate and wait until the water velocities go back down to ideal. For the foothill yellow-legged frog, oviposition, or the depositing of eggs, is somewhat sporadic because delays such as rains could cause problems such as unwanted removal of eggs. The males also perform mating calls mostly underwater, and those above the water are faint and hard to hear over 50 m. After the frogs have successfully mated, the egg masses are laid about 0.5 m attached to rocks underwater in streams and rivers with flow velocities ranging from 0.1 to 0.6 m3/second. These egg masses can contain 100 to 1000 eggs in one batch, contained in a bluish gel that disappears once the eggs take on water, and the dark ovum, the center of egg, is covered by three jelly envelopes about 5.4 mm in diameter. Eggs hatch in about five to over thirty days depending on the temperature that the mass is at and the surrounding water. The tadpoles continue to stay associated with the egg mass for several days, and continue to need higher temperatures to grow quickly. By the time the tadpoles reach about 40 mm, roughly 1.5 in, they are adults and their reproductive organs are mostly functional. The frogs are usually fully developed by the summer after their first metamorphosis, though some begin breeding after six months. Range and Habitat Foothill yellow-legged frogs occur in the Coast Ranges from the Santiam River in Marion County, Oregon south to the San Gabriel River in Los Angeles County