Fox Squirrels (Sciurus niger) are a sore subject for GNG for they are not native and pushed out populations of native western gray squirrel. Yet, they have been living in California for over 100 years. History states the first population arrived in Los Angeles by way of Civil and Spanish war vets who kept them as pets. From there they escaped and started colonies. Today, they are most likely the squirrel you see in you backyard.
Did you think the one on the lower branch didn’t see the other till it looked up?