Peruvian Band of Holes - photo

[mccwho]

Since the pits were built up with dirt and rocks and not dug into the rock (so they would not have held water. They might have been used to slow enemies or used to direct migrating animals since animal are like humans and prefer to take the path of least resistance. Might even have been used to capture or injure migrating animals.
Depending on past weather or the different climate they would have had back then. They could have even been used as food storage.