Acorn Woodpeckers Turn Vacation Rental into Nutty Storage Unit

Pest control specialist Nick Castro discovered roughly 700 pounds of acorns that acorn woodpeckers had cached inside the chimney and walls of a rental home in Glen Ellen, California, north of San Francisco.

The birds had pecked holes in the chimney stack, and the hoard piled up about 20 feet high inside the chimney over an estimated two to five years.

Castro, owner of Nick's Extreme Pest Control, cut into a bedroom wall during the inspection and watched the nuts keep spilling out, saying the more acorns he pulled from the wall, the more there were.

The stash ultimately filled about eight garbage bags and was contaminated with rat feces and fiberglass.

Castro said he had never seen anything like it and joked on Facebook that the bird was a bit of a hoarder even by bird standards.

Acorn woodpeckers are famous for granary behavior, storing acorns one by one as a winter food supply, and Castro's crew removed the hoard and arranged repairs for the home's damaged siding.

The Glen Ellen chimney is textbook behavior at scale: a single granary tree can hold 50,000 acorns or more, per UC Oaks, and the birds spend winter tapping each nut into a tighter hole so squirrels and jays cannot pry it loose, as KQED explains. The commune behind the hoard is the stranger part. Hastings Natural History Reservation, which has monitored a color-banded population in Monterey County since 1974, records groups of up to seven cobreeding males and four joint-nesting females plus helpers, all defending one larder. The loser is whoever owns the siding, since the birds never pay for repairs. Before the next fall acorn drop, sealing the chimney and eaves is cheaper than eight garbage bags.