The eggs are attached to vertical emergent vegetation such as bulrushes or cattails. The eggs hatch in 6 to 14 days and, approximately 3.5 to 7 months later, the tadpoles develop into frogs. Tadpoles and young frogs thrive on invertebrates, which they catch with their mouths. They hunt day and night. This constant activity makes them visible, and, therefore, more vulnerable to predators.
Adults feed and are active largely at night.
Over the last two decades, scientists have noted a widespread decline of frogs and other amphibians, the causes of which are not fully understood. The decline of the California red-legged frog is attributed to the spread of exotic predators such as bullfrogs, and the widespread changes that have fragmented habitat, isolated populations, and degraded streams. Bullfrogs, introduced to California from Maryland and Florida in 1896, are more suited to survival in human-disturbed areas than the native ranids, partly because they can tolerate warmer water temperatures. The decline signals a loss of diversity and environmental quality in wetlands and streams that are essential to clean water and to the survival of most fish and wildlife species. Public comments are being reviewed.