Ask the Naturalist

Ask the Naturalist: Wall-to-Wall Blue Jays?

September 5, 2014

Q: I  live in North Berkeley. Over the years I’ve noticed fewer blue jays and more (and more!) crows and ravens. In the last few days, it’s been wall-to-wall blue jays. What’s going on?  — Peter B., Berkeley

A: (Provided by Ilana DeBare, Golden Gate Audubon)

Peter,
You’re not seeing Blue Jays, which are East Coast birds. If you’re seeing blue-colored jays with a peaked cap on their head, they are Steller’s Jays. If they have rounded heads without a peak, they are Western Scrub-Jays.

The local population of both species seem pretty stable. Since 1999, the Oakland Christmas Bird Count total for Steller’s Jays has fluctuated between 195 and 539. For Scrub-Jays, between 382 and 750.

The 2013 Oakland CBC tallied 446 Steller’s and 663 Scrub-Jays in its 10-mile circle, which includes Berkeley. That’s nowhere near as many as crows (1224) but still a healthy number.

So on an areawide level, they are not being chased or crowded out by crows.

I can’t say why you’ve been deluged with jays recently, but maybe they found a particularly tasty food source. Like the crows who are also in the corvid family, jays are very intelligent birds. They eat many types of insects and small animals. So it could be anything… maybe a bunch of caterpillars all coming out at the same time, or a particular kind of berry ripening.

>> Looking for local population trends over time for bird species? Download  historical CBC records from the National Audubon Society site at: netapp.audubon.org/CBCObservation/

>> Contribute to future bird data by joining Golden Gate Audubon’s 2014 Oakland Christmas Bird Count (CBC) on Sunday, December 14 or the San Francisco CBC on Tuesday, December 30. It’s free, and open to beginning as well as experienced birders.

 

 

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