Exterminator Nick Castro was inspecting a home for mealworms when he discovered something … nuts. Tens of thousands of acorns came cascading out from behind a bedroom wall.
“Unreal,” Castro posted on his company’s Facebook page. As he reached behind the wall, the little oak nuts kept spilling out. Castro – who owns Nick’s Extreme Pest Control in Santa Rosa, California – said he filled a total of eight garbage bags with 700lbs of acorns.
They had been stashed there by acorn woodpeckers – peculiar little birds with a shock of red feathers on their head – who are prodigious acorn collectors. Normally, the birds store thousands of acorns in small holes they drill into dying tree stumps, which they protect with outsize pluck.
“But that instinct to fit an acorn in a hole and store it is pretty strong with these guys,” explained Angela Brierly, a PhD researcher at Old Dominion University who studies the species at the Hastings Natural History Reservation.
In this case, it appeared that the woodpeckers, who had initially tried storing their nuts in the house’s wood siding until a previous owner wrapped the house in vinyl, began stacking them inside the chimney, Castro told the Press Democrat.
Because the nuts kept falling into a wall cavity, the birds couldn’t access them. So they kept filling the gap with more and more acorns. “Bird was a bit of a hoarder,” he wrote on Facebook. “Never came across something like this.”
Generations of woodpeckers can take up to 100 years to perforate large trees with 50,000 acorn cubby-holes, said Brierly. The birds form polyamorous families with up to seven males and four females, who are joined by other relatives that help them raise their young.
Sometimes staging spectacular battles, these families defend their granaries in oak forests across coastal Oregon, California and Mexico. “Of course these are acorn woodpeckers,” Brierly said. “So their entire ecosystem, life history and way of living revolves around acorns.”
Brierly, who studies the birds’ social dynamics, said friends and family from all over the country have been sending her the news of Castro’s acorn discovery. “I love it!” she said – though she’s been trying not to respond with too many woodpecker facts.
“They’re incredibly charming,” she said. “They’ll hold their wings out in a funny little way when a friend or family member shows up, and they will do a funny call – an almost laughing sort of greeting, and a little dance that goes with it.”
The birds have adapted to urban environments all along the west coast of the US, she said, which has made them more resilient than other species to changes in their habitat and human development. “Unfortunately, sometimes that also means they’re storing acorns in people’s homes or sheds,” she said.
Birders across the west can watch them fuss over their granaries, looking for the perfect hole to store their acorns in. “So some acorns are fat and squat, some are long, narrow,” Brierly said. “So they’re trying to fit a puzzle piece in the right spot. Sometimes they slightly adjust the size of the hole to make it fit snug.”
Whatever they store is used to sustain them through the fall and winter, and to help them feed their babies in the springtime. They’re relatable in that way, Brierly said. “That’s what you and your family are essentially trying to do as well – saving for the future, saving to pass down to future generations.”
Castro, sadly, said he had to throw out the acorns he found behind the wall because they had been contaminated by fibreglass insulation and rat droppings. But the birds probably had more stored up in nearby trees. “If they find a hole and an acorn fits, an acorn is going to get put in it,” Brierly said.
