Chicken Tractor?

[jas67]

In looking for tractor-related items on CL, I occasionally see ads for "Chicken Tractors." I know from googling the term that it is a chicken coup. What puzzles me, is the name. Why is it called a chicken tractor?

 

[cowboy357]

I also wondered that awhile back , I Beleive its because there portable . Heres what Wikipedia says . Bob

Chicken tractor - Wikipedia, the free encyclopedia