Pacific Tree Frog - Reproduction, Development and Behavior

Reproduction, Development and Behavior

The Pacific Tree Frog begins mating in early winter to early spring. Since these frogs are so widespread geographically, it is thought that their breeding season is determined by local conditions. When it is time, the males migrate to the water. They then make a call at the same time, calling "kreck-ek" or ribbiting loudly. This lures the females to the water and they mate. The females lay their eggs in clumps of 10-90 and usually put them on and under vegetation and leaf litter in the pond. Females usually lay their eggs in shallow, calm water that has little action around it. If they survive, embryos will hatch into tadpoles within one to three weeks. The tadpoles feed on periphyton, filamentous algae, diatoms, and pollen in or on the surface of the water. They feed using suction, and a beak like structure that helps scrape vegetation off surfaces.

Metamorphosis usually follows about 2 to 2½ months later, but experience raising these tadpoles shows that some may delay metamorphosis, changing up to 5 months after hatching. The survival rate of these delayed metamorphs is lower, and the evolutionary utility of this delayed metamorphosis is uncertain. It may be related to the prevalence of fire in their natural ecosystem.

During the final stages of transformation when the tadpoles have 4 limbs and a tail, they stop feeding for a short time while their mouths widen and their digestive system adjusts from herbivorous to carnivorous.

For the most part, Pacific Tree Frogs are nocturnal, but they have been spotted during the day. These frogs spend a lot of time hiding under rotten logs, rocks, long grasses, and leaf litter, where they are very difficult to see unless they move. When they hunt, their toe pads allow them to climb on vegetation and other surfaces where they are to ambush their prey. Much of their diet consists of spiders, beetles, flies, ants, and other insects and arthropods; they can and do eat insects that are almost as large as they are, and will expand their bodies slightly to accommodate these meals.

Pacific Tree Frogs mature quickly, and are usually mate the season after metamorphosis. Predators include snakes, raccoons, herons, egrets, and other small mammals and reptiles.

When they sense potential food nearby, they commonly twitch a toe to attract it within easy reach of their tongue. They can live up to 9 years in captivity.

They produce several call types. These include the males' advertisement call, commonly described as “ribbit” or “crek-ek”, as well as an encounter trill call. The cre-ek call can be quite loud and can thus be heard from very far away. Males also produce a “dry land call”, a long cre-ee-ee-eeek, that can be heard anytime in the year except during the coldest and driest periods. Pacific Tree Frogs are the most commonly heard frogs along much of the West Coast of the United States.