Each year thousands of vibrant orange and black Monarch Butterflies flock to Pismo Beach, seeking shelter from the freezing northern winters. From late October to February, the butterflies cluster in the limbs of a grove of Eucalyptus trees. The butterflies form dense clusters with each one hanging with its wing down over the one below it to form a shingle effect. This provides shelter from the rain and warmth for the group. The weight of the cluster help keeps it from whipping in the wind and dislodging the butterflies. This colony is one of the largest in the nation, hosting an average of 25,000 butterflies over the last five years.