Recently a California homeowner was surprised when reptile rescue pulled more than 90 rattlesnakes from the house’s foundation. The haul included 22 adults and 59 juveniles, plus eleven more on a second trip.
The foundation apparently had become a rookery: a place where rattlesnakes gather to give birth. Rattlesnakes actually birth their young alive. Sometimes females give birth alone; other times, they gather in rookeries. These rookeries are more common in higher elevations where there are fewer warm dens to be found. Otherwise, we really don’t know why some snakes choose rookeries and others stay by themselves. Normally, the choice of a house foundation is surprising, but this area was ideal because most of the rocks in the ground had been left in when the foundation was dug.
By the way, the snakes were released away from human habitation. And if you ever find yourself in such a situation, improbable as that may be, there is a Free Snake Relocation Directory which contains contact information for volunteer snake relocators around the United States.
Taken from “Why did more than 90 rattlesnakes move into a California home?” by Stephanie Pappas (https://www.livescience.com/92-rattlesnakes-under-california-home?).