While out at Yosemite National Park a few weeks ago I made a stop at Sentinel Beach to take a look at the Merced River. There were a lot of these California ground squirrels (Otospermophilus beecheyi, Sciuridae) foraging near the path. Given the considerable human activity at this location in the park, they may have been foraging in part for human food left by passers-by.
What really stood out about these squirrels were their striking coats. Behind the black ears were saddles of silver grading into mottled silver/black/brown colors on their bodies. The coloration reminded me of some birds. I suspect this serves as camouflage to some extent, helping to protect them from numerous predators.
Despite the predators, the adaptability and high reproduction rates of California ground squirrels make them among the most common Sciurids in the American west. Their prevalence made it easy to identify them, but despite their abundance they were still pretty cool for an easterner like me to see.