A zoo spokesperson said the behavior is called an “alert circle” and said it is “intended to protect the young — and the entire herd — from threats.”

A herd of elephants at the San Diego Zoo acted on instinct and formed an “alert circle” around their young to protect the calves against the earthquake that rattled Southern California on Monday, amazing video shows.

The zoo reported the herd returned to normal behavior a few minutes after the earthquake, though they continued to remain close.