Hyla regilla

INTRODUCTION

The Pacific tree frog (Pseudacris regilla), also known as the Pacific chorus frog, has a range spanning the Pacific Northwest, from Northern California, Oregon, and Washington to British Columbia in Canada and extreme southern Alaska.[2] They live from sea level to more than 10,000 feet in many types of habitats, reproducing in aquatic settings. They occur in shades of greens or browns and can change colors over periods of hours and weeks.

MORPHOLOGY

• The Pacific tree frog grows up to 2 inches from snout to urostyle.

• The males are usually smaller than the females and have a dark patch on their throats. The dark patch is the vocal sac, which stretches out when the male is calling.

• They have a variety of dark and spotty markings on their backs and sides and can be identified by a black or dark brown eye stripe that stretches from the nose, across the eye, and back to the shoulder.

• Their skin is covered in small bumps.

• They have long legs compared to their bodies and they tend to be slender.

• Their toes are long and only very slightly webbed. On the end of each toe is a round, sticky toe pad or disk used for climbing and sticking to surfaces.

• Males also have an extra, and far less noticeable toe on their outer thumbs used exclusively in amplexus.

HABITAT

• They are found upland in ponds, streams, lakes and sometimes even further away from water; their habitat includes a wide variety of climate and vegetation from sea level to high altitudes. 

• The Pacific tree frog makes its home in riparian habitat, as well as woodlands, grassland, chaparral, pasture land, and even urban areas including back yard ponds.

REPRODUCTION AND DEVELOPMENT

• Fertilization is external. The Pacific tree frog begins mating in early winter to early spring. Since these frogs are so widespread geographically, their breeding season is thought to be determined by local conditions.

• When it is time, the males migrate to the water. They then make a call at the same time. 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 two to two and a half months later, but experience raising these tadpoles shows that some may delay metamorphosis, changing up to five 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 four limbs and a tail, they stop feeding for a short time while their mouths widen and their digestive systems adjust from herbivorous to carnivorous.