The Jack Russell Terrier was developed in Devon, England, to keep up with foxhounds and flush foxes out of their dens. That job explains most of what you see today: a compact, mostly white dog of 13 to 18 pounds with black or tan markings, a smooth, broken or rough coat, and a nose that never really switches off.
In Norwalk, that means a dog who notices every squirrel, gull and rabbit, so a snug harness and a secure leash matter on trails and shoreline paths. Jack Russells are clever, funny and devoted to people who train them, though many are stubborn and vocal. A dog's age, history and training shape its behavior, so spend real time with a dog before you decide.