Squirrels are almost ubiquitous in urban/suburban environments, so it's no challenge to find them. They also become "tamer" than most wildlife, as they're so used to proximity to human dwellings. Not to mention the occasional handouts of seed...
Although they are "just rodents", and a lot of people would much rather be surrounded by birds of almost any type (rock doves, aka pigeons, might be an exception), squirrels can have their charm. At any rate, I like to practice photographic skills on the things that I see regularly (if you can't be with the one you'd shoot, shoot the one you're with?), and it's still a challenge for me to catch interesting postures and expressions, maybe occasionally with some interesting background colors.
[Canon 1DMkIV, f/4, 1/320 sec, ISO 1600, 300 mm w/ 1.4X extender]