They were subsequently developed into two modern breeds: the Australian Cattle Dog and the Australian Stumpy Tail Cattle Dog. Robert Kaleski, who wrote the first standard for the breed, was influential in its development. Australian Cattle Dog has been nicknamed a 'Red Heeler' or 'Blue Heeler' on the basis of its colouring and practice of moving reluctant cattle by nipping at their heels. Dogs from a line bred in Queensland, Australia, which were successful at shows and at stud in the 1940s, were called 'Queensland Heelers' to differentiate them from lines bred in New South Wales; this nickname is now occasionally applied to any Australian Cattle Dog. The breed standards of the Australian, American and Canadian kennel clubs specify that the Australian Cattle Dog should have a natural, long, un-docked tail. There will often be a solid colour spot at the base of the tail and a white tip. The tail should be set moderately low, following the slope of the back.