I believe this may be a cougar call. Merlin could not identify it as a bird sound.
Macrocarpa x lobata
Many more pairs lateral veins. Similar color top and bottom, not fuzzy underneath.
One individual about 7m tall. Slightly lobed lvs 3-6cm, abaxially dull. Appears evergreen but hard to say for sure (May).
Close up of oak leaves, with 2 acorn caps - the only one with fruit it in that I found fell under the shrub before I got a close look or pic. I think this is leather oak.
A wild volunteer. This species readily self-seeds in CA.
Possibly Q. agrifolia x parvula.
GPS approximate based on memory, needs refining. On trail with Salix in middle, Q. parvula at crossroads end.