This week’s bird is the acorn woodpecker.  Its distinctive, laughing call is the basis for Woody Woodpecker’s laugh, although his appearance is based on the pileated woodpecker.  These birds live in oak forests along the west coast and southwest of the US, down through Central American and into Colombia.  These woodpeckers practice collective breeding, or, more formally, are organized into “polygynandrous breeding collectives.”  Although some are monogamous pairs, these collectives will include up to eight males and four females, who all care for young regardless of who issued from whom.  They utilize something called “helpers at the nest,” which are non-breeding (juvenile and adolescent) members of the group who help raise new young.  “Cooperative breeding, defined as more than two birds taking care of nestlings in the nest, is a relatively rare evolutionary trait that is thought to occur in only nine percent of bird species.^[12] Most cooperative breeding species have helpers at the nest, but acorn woodpeckers are unusual in exhibiting both helping at the nest and cooperative polygamy (polygynandry).”  All of the birds will lay their eggs in a single nest and raise the resulting offspring in common.  Usually the male members are brothers or fathers and sons, and the females are sisters or mothers and daughters.  If an adult member of the group dies or leaves, it is replaced by a bird from outside the existing group.  This helps keep the woodpeckers from in-breeding, although they do tend to be very closely related.

Acorn woodpeckers rely heavily on acorns for food, as their name implies.  They will drill holes in dead trees or dead parts of trees and cram an individual acorn in each cavity.  These trees are called granary trees, and can contain thousands of holes for storage, and the trees are reused year after year.  A member of the group is always on alert, keeping watch over the horde, and if the horde is stolen or destroyed the group will move on, sometimes covering great distances to find a new source of nuts.  Despite all this rigmarole, the acorns so lovingly tended are a backup food source and the acorn woodpecker mainly feeds on bugs, sap and fruit.   

The acorn woodpecker is threatened by habitat loss and competition for food storage space from invasive species or in urban environments.  It is, however, listed as “non-threatened,” and I found several tips online on how to attract the birds to your yard.  This info is probably in one of the source links at the end of the post, who can remember. 

Special hat-tip this week to Nate the Lesser, who helped me banish whatever demon was haunting my wordpress editor. Thanks, Nate!

Links: https://tinyurl.com/a2mjkj9e, https://tinyurl.com/yck7swnn, https://tinyurl.com/3h8nz63x