Life History, Abundance, Activity, and Special Behaviors
Eggs: Clusters of eggs are deposited in a ponds shallow water, usually at depths above 4 inches. The clusters can be attached to sticks, leaves, vegetation, or other objects, and they can also be found floating on the surface, usually attached to objects. Eggs are usually laid in loose clusters of irregular shape, and the cluster has 2 gelatinous envelopes. The outer envelope is 4.78 to 6.7 mm and is sticky, and the inner envelope is 1.88 to 2.70 mm. Each packet usually has 22 to 25 eggs, but could have anywhere from 5 to 60 eggs. As the layings near an end, the number of eggs per clutch can decrease to 3 or 4, or even single eggs (Livezey and Wright 1947).
Larva: The tadpole is about 45 mm long, full and deep-bodied, and has a fairly long tail, about 2 times the head and body length. The labial tooth row formula is 2/3, and the spiracle is sinistral, directed posteriorly (Grismer 2002). The general color is blackish and yellowish brown to dark brown with heavy black spots. Below, it is whitish with bronze or copper tinges. The tail is mottled with black, and the iris is golden, with a darker area anterior and posterior to the pupil (Stebbins 1951).
Call: H. regilla is the most commonly heard frog species on the Pacific coast. The calls last for about 1 second and are often uttered in sequence. Each 1-second call consists of a loud, two-parted 'kreck-ek', with rising inflection in the last syllable. H. regilla has a round vocal sac (Stebbins 1985). While singing, a male may float with his limbs outstretched and his globular pouch extended to or beyond his chin (Stebbins 1951).
Food: H. regilla eats insects, including leaf-hoppers, spring-tails, flies, stoneflies, ants, wasps, beetles, and caterpillars, It also eats spiders, isopods, and snails (Stebbins 1972).
Behavior: H. regilla is mainly nocturnal, but it is also active in the daytime. Sometimes, at low elevations, it is active throughout the year. It is a good climber, but usually stays near the ground. It has a great capacity for color change, and a change from an unspotted dark coloration through a medium light colored phase with spots to an unspotted light phase may take about 8 to 10 minutes (Stebbins 1951).