Kestrel

I've noticed a kestrel in my neighborhood.  He sits on a wire overlooking a grassy park.  He stares intently a the ground looking, I suppose, for a meal of mice, grasshoppers, moths or voles.  With their keen vision and ability to see ultraviolet light, they can see the line of urine that a mouse or vole has left behind.  The kestrel will be gone for a couple weeks and then return to the same spot.  Does he eat all the food in sight and then go to another spot for a couple weeks while the populations of mice and grasshoppers recovers?  I drive by this spot only twice a day so my sampling is not very thorough.  I enjoy seeing him though.  I'm glad my neighborhood has enough diversity and habitat to support a fierce predator like a kestrel.