This series of images shows the entire life history of a Pacific treefrog, from egg to tadpole all the way through metamorphosis to adult.
All photos by Jo Wilhelm unless otherwise noted.
1. Pacific treefrogs lay eggs in clusters of 10-80 typically attached to vegetation in shallow, still water. Each cluster is a soft, irregularly shaped mass that does not hold its shape out of water. A single female frog lays 20-30 egg clusters in a breeding season. The eggs here are in the early stages of cell division.
2. Pacific treefrogs breed primarily in January and February. But eggs have been found every month from December through September depending on elevation and latitude. The embryos here have developed a tail bud.
3. Eggs generally hatch in 2-3 weeks, but the time varies based on water temperature. One dead egg is visible in this picture (the opaque white circle), whereas the other embryos are very developed and are likely close to hatching.
4. The larval stage (the tadpole!) lasts 2-3 months after egg hatching and before transforming into frogs. The tadpoles feed on small organisms suspended in the water such as algae, diatoms and bacteria, and organic and non-organic detritus. Pacific treefrog tadpoles have eyes set toward the side of the head. If viewed from above the eyes protrude beyond the outline of the head, like in this photo.
5.Tadpoles can vary in color from dark brown to olive green sometimes with mottling and with a creamy white underside.
6. Transformation into frogs typically takes place from June through August. Also note that Pacific treefrogs have an eye stripe that extends from the snout and stops at the shoulder.
7. Pacific treefrogs are small to medium-sized frogs. Recently transformed frogs are sometimes less than 10 mm in length, and adults can range in size from 25 to 50 mm.
8. Dorsal color (the color on their back) is not used in identification because adults are highly variable. Their colors range from brown or green to gray, tan, reddish, bronze, or black.
photo by J. Vanderhoof9. Pacific treefrogs have expanded toe tips. They are distributed from British Columbia to Baja California in Mexico and from the Pacific Ocean west to Montana, Idaho, Nevada, and Arizona. They range from sea level to 3,550 m elevation.
10. Pacific treefrogs are the most abundant frog in our region and are the most commonly heard frog calling throughout the day during the peak breeding season. Adults feed on small invertebrates including insects, spiders, isopods, and snails. Who feeds on Pacific treefrogs? Fish, snakes, herons, egrets, raccoons, skunks, river otters, and larger frogs all feed on treefrogs.