I see gray squirrels  around this area every day. There are a lot of them.
Sometimes they sit and watch as you walk down the sidewalk and then dart up a tree or elsewhere.
Gray squirrels are quick movers. They dash around in a hurry. They are also good climbers.

All the pictures are from Wikimedia Commons.

By, Zipamapa.

Eastern_gray_squirrel Zipamapa WCBy Whpg.

WhpgBy Sebastian Wallroth.

640px-Eastern_gray_squirrel_1886 Sebastian Wallroth WCBy Robert Bauer.

Gray_Squirrel_London_St._James_Park_Padlock Robert Bauer WCBy Bonnie Gruenberg.

Bonnie GruenbergBy Ed Sweeney.

Ed Sweeney WCThese last three pictures are in order and taken by, waferboard.

538px-Sciurus_carolinensis_-British_Columbia,_Canada-8 waferboard WC581px-Sciurus_carolinensis_-British_Columbia,_Canada-8_(1) waferboard WCSciurus_carolinensis_-British_Columbia,_Canada-8_(2) waferboard WC