they aren't very common, in the US I think they are most common in the southern midwest (missouri, kentucky, tennessee, arkansas) and the south east...atleast they were in the early 90's when I first heard about them. they are extremely similar to the jack russel terrier in build and temperament, very popular with squirrel and rabbit hunters and with falconers. my brother is a falconer, got his license at 14 (which is awesome because the minimum age is 18...long story) and falconers use small dogs (terriers, beagles etc) to flush rabbits out of thick brush for the hawks to kill. most falconers (I really only know about falconers in Missouri where we lived for 18 years) use jack russels, second most popular is rat terrier, some use patterdales. '
it was probably 1993 when I first saw a patterdale. I'll always remember them because when I first saw one I thought it was a jack russel x lab mix.
okay okay...bunch of useless info.