Acorn Woodpeckers, one of the most common birds of oak woodlands in California, are also one of the most highly social birds in the world, living in family groups of up to 15 individuals. The intricate social behavior of this species has been studied for the past 25 years at Hastings Reserve, part of the University of California Natural Reserve System, by Adjunct Professor Walt Koenig of the Department of Integrative Biology.