The Call of the Treefrog

Pacific treefrogs (Hyla regilla) are the most commonly heard frog on the Pacific Coast. They can be heard calling from late fall through early spring in almost any freshwater habitat throughout California.

Males chirp a high-pitched kreck-ek! to lure females to ponds, streams, or water-filled, roadside ditches to mate. Females lay gelatinous egg masses about two inches in diameter attached to vegetation in shallow water; males fertilize the eggs externally. Tadpoles metamorphose into froglets one to two months after hatching.

Hyla regilla Pacific treefrog
Photographer: Dr. Robert C. Drewes
Hyla regilla Pacific treefrog
Photographer: Jens V. Vindum

Despite their name, Pacific treefrogs are hardly ever found in trees. Preferring grasses near water, they inhabit almost any habitat except deserts from the coast up to about 11,000 feet above sea level in the Sierra Nevada.

Treefrogs range in color from green to light brown. However, they can change shade throughout the day, probably to regulate their body temperatures. For example, a green treefrog may turn lime green when it's warm and it needs to cool, and a deep forest green when it needs to warm up.

Around the San Francisco Bay Area, some good places to see Pacific treefrogs include Mount Tamalpais State Park, Tilden Regional Park, and the Crystal Springs Reservoir.