The highly social Acorn Woodpecker. A king of industry. Threatened by forest fires.
Truly a bird that lives up to its name, the Acorn Woodpecker spends its life gathering acorns and drilling holes in trees to cache the stash. These woodpeckers live in small defined ranges on the west coast and create granaries or "acorn trees" by drilling holes in trees, dead branches, telephone poles, and wooden buildings. The woodpeckers then collect acorns and find a hole that is just the right size for the acorn. As acorns dry out, they are moved to smaller holes and granary maintenance requires a significant amount of the bird's time
The acorns are visible, and the group defends the tree against potential cache robbers like Steller's jays and western scrub jays. Acorns are such an important resource to the California populations that acorn woodpeckers may nest in the fall to take advantage of the fall acorn crop, a rare behavior in birds. They are so good at storing acorns that in 2012 Woodpeckers put 490 lb of acorns into one wooden water tank in Arizona.
Acorn woodpeckers practice cooperative breeding, which is a relatively rare evolutionary trait. Cooperative breeding is defined as more than two birds taking care of nestlings in the nest. With the acorn woodpecker, cooperative breeding occurs in two ways: coalitions and family groups. Coalitions of adult acorn woodpeckers nest together, localizing to storage granaries. Additionally, adult offspring often stay in their parents' nest and help raise the next generation of woodpeckers. It is generally believed that limited territories drive cooperative breeding behavior in birds, and in the case of the acorn woodpecker, this limited territory is the acorn storage granary.
Right now their small range is under threat from the many forest fires in California.