A straight line distance between two places. A human would have to travel further to get from one point to another due to obstacles or lack of roads or trails, but a Crow can go in a straight line between them.
The shortest path between two points on the earth's surface, without any detours for lack of roads, fences, cliffs,etc. The technical name for this is a geodesic.
Crows are very smart and curious. It was probably checking to see if you had food or were looking for food and could steal some. They learn very quickly that if a human is near (farmers) food is near...