I live in an area where there are several types of squirrels, all good for chasing. There are lots of ordinary ground squirrels with burrows in the ground. Some people call these squirrels "prairie dogs" which is pretty silly because they don't look or act anything like us dogs.
There are also common gray squirrels who mostly live in trees. They scamper back and forth along the power line in our back yard. When we see this type of air space violation, we charge out the doggy door and bark like crazy until the intruder squirrel goes away. One squirrel actually sits on the power line and flicks his tail to taunt us. He has no respect for our territory! One of these days, squirrel, you'll get yours!