Are Danville acorn woodpeckers confused by climate change?

DEAR JOAN: Every year, we have six or more acorn woodpeckers at our bird feeders daily though the spring and summer. We love their cackling calls, red heads and colorful faces. They all disappear in September and return in the early spring.

We were surprised to see two of them back this month. Where did they go for four months? It’s not warm enough for them to have returned from a migration, or do they migrate for other reasons?

We also have a nesting pair of Western bluebirds that came back in December this year. They’re in the birdhouse making a nest! They usually come in the spring after leaving in September or October, just like the woodpeckers.

Two species returning earlier than usual. Is this somehow related to climate change? Or just something weird about our yard?

Teresa S., Danville

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DEAR TERESA: Climate change is having an impact on wildlife and the world in general, but I’m not certain that’s what’s going on in your yard.

While all birds migrate, the extent they do it varies greatly. While some birds travel thousands of miles, other birds migrate just a few miles. Acorn woodpeckers and Western bluebirds are among those that do not really travel and are considered permanent residents of the Bay Area.

They might relocate in search of food or housing, but they don’t leave the general area. Acorn woodpeckers never move far from their storehouses, whether that be granary trees or stockpiles of acorns in other places. I suspect that when your acorn woodpeckers disappear from the feeders in the fall, it’s because they are busy harvesting acorns for the months ahead.

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Acorn woodpeckers spend much of their time in food storage collection and maintenance. First, they create the holes or find natural cavities, then they search for the perfectly sized acorn to fit the hole. As the acorns age and dry out, they shrink and the woodpeckers move them to more appropriately sized holes. These are very busy birds.

The Western bluebirds also hang around all year, but they don’t live inside the nesting boxes. The exception to that is when it’s cold and stormy. The birds might move back into the nesting boxes and use them as shelters. The bluebirds that have moved into your nesting box might be hanging out there to stay warm and dry.

Acorn woodpeckers have been known to start mating in the winter, if the acorn supply is bountiful, but bluebirds won’t start families until spring, when there is a good number of insects available to them and their hatchlings.

Enjoy your early visits.

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