Oregon Spotted Frog - Reproduction

Reproduction

The Oregon spotted frog’s reproduction is strictly aquatic and their late winter breeding season is brief, less than four weeks in duration. Males call quietly during the day or night from the vicinity of traditional oviposition sites, places where females lay their eggs in communal piles. Ovipostition at selected sites is initiated when water temperatures reach 8ºC, but the timing of oviposition varies from late February-early March at lowland sites to late May-late June at montane sites in Oregon. They breed in warm shallow water, often 2-12 inches (5-30cm) deep in areas where grasses, sedges, and rushes are usually present. Adult females reportedly breed every year and probably produce a single egg mass each year. Though egg masses are occasionally laid singly, communal oviposition sites usually comprise the majority of the annual reproductive output. These communal clusters of egg masses are often composed of between 10 and 75 individual egg masses and in British Columbia it has been recorded that each egg mass contained an average of 643 eggs. They lay their eggs in fully exposed, shallow waters that are readily warmed by the sun so that development to hatching is hastened by warm conditions. However this also increases the vulnerability of the eggs to desiccation and/or freezing.