Birds nest on the ground

I am interested to know the origin of the phrase, "birds nest on the ground".

Here is what was said previously about its meaning:

"A bird's nest on the ground" describes some thing or some situation that is rewarding to the owner in a very big way. Another similar phrase: "low hanging fruit." Meaning a task that is done easily.

I don't know about its origin except that a bird's nest on the ground would be easier for a cat to get to than one in a tree.