Australian Shepherds are the best. Very smart, and very protective (of their adopted herd).
Usually they will try to herd anything; other dogs, cats, birds, geese, ducks, fish, people. If it thinks any moving animal can be herded it will make the effort. Several times she actually caught crows (with her legs and paws) before they could take off... and try herd them.. of course when she uncovered them the would take off... or try to. Quite a sight to see.
Oh, and ours dove under water to retrieve any rock you threw in the lake or the ocean. It it brought up what it thought was the wrong rock it would drop it back in and try again.
We could delineate areas by drawing a line on the floor with our finger (like a kitchen tile or edge of a rug, or even a spoon we set on the floor. The dog would not cross the line. Would stand just at the line looking sad and sometimes whining, but would not cross.
Smokey was a very smart dog. She is very missed.
The herding behavior is just amazing.
My dog herds the cat, and squirrels all day long. She will just gargoyle at the back door and wait for them to come for their peanuts, then she beats on the glass and comes and herds me to open the door for her so she can chase them out.
But while I do agree that Australian Shepherds are also amazing animals, the German Shepherd is the most magnificent looking dog I have ever seen.
They are just drop dead gorgeous, plus the intelligence and personality and loyalty, so they are my heart.