As we were unable to consult our field guide, since it only covers northeastern states, we searched the web and found out that your little frog friend is a Pacific Treefrog, Pseudacris regilla. Some very nice pictures can be found here. He is apparently well-known for his big froggy voice, commonly used by Hollywood for sound effects. Fun! Thanks for documenting the little guy. The boys really enjoyed looking him up and learning more about him.