On the Fly – Screamin' Jays

Back east they have blue jays. But if you were talking about a blue jay around here, everyone would know what you meant, right? Not really. I used to think Steller’s jays and scrub-jays were the male and female versions of “blue jays,” and I bet I’m not the only one. But as I said, the blue jay (Cyanocitta cristata) lives elsewhere. The Steller’s jay does live in the West. It’s that one with the crest. And the western scrub-jay is the other big, loud, blue one.

 The Steller’s jay (Cyanocitta stelleri) is named for botanist, zoologist, physician and explorer Georg Wilhelm Steller (1709–1746), who in his short life also managed to have a sea eagle, sea lion, sea cow and sea duck named for him. These jays like forested areas and are common in the mountains, but we see them here in Martinez, too. In fact, I know a nest close to Alhambra Creek where a female jay is incubating her eggs right now. The western scrub-jay (Aphelocoma californica), on the other hand, loves the dry oak woodland habitat that is emblematic of Contra Costa County. In both of these species, the sexes look alike. The male and female both build their nests. Like many baby birds, their young are altricial: blind, naked and helpless when hatched (the opposite is “precocial”). This is said to be where the expression “naked as a jaybird” comes from.

 Are jays just a bunch of noisy obnoxious predators? Oh, what’s the point of being judgmental about it? Yes they’re loud, their calls are grating, and female Steller’s jays often sound like they’re gargling gravel. But the male sings sweet little songs when he’s spending time with his mate at the nest. And they’re also great mimics. If you hear the call of a red-tailed hawk nearby—that long, loud, descending whistle-shriek—take a second look because it might be a Steller’s jay. Last year I caught one doing this and then saw it swoop away in a hurry when a real hawk came around to investigate. They probably do this to scare away competitors for food, but it sure looks like they’re just trying to stir things up sometimes. Though much of their diet consists of seeds, berries, and nuts, it’s true that jays steal eggs from the nests of other birds, and it is a heartbreaking sight. But it’s also true that the ruckus they raise when they spot a predator—and they’re always on the lookout—is a warning to every other bird and small mammal in the vicinity.

 Beyond the annoying yet heroic activities of individual jays, there is their overall impact on the landscape to consider. The wind won’t blow an acorn around the way it will a flower seed, and so these noisy birds and their mammalian counterpart, the squirrel, perform an essential service as “seed dispersal agents.” To ensure they’ll have enough food when times get tough, jays stash acorns on the ground under shrubs or in leaf litter. (They may actually be storing them so that groundwater will percolate through them and leach out bitter tannins.) One scrub-jay caches about 5,000 acorns in a season. He or she may remember where 95 percent of these acorns are and go back to eat them, but some of the 5 percent that don’t get eaten will germinate, and that’s how oak woodlands get regenerated.

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 The annual Heron Watch has been happening at Stow Lake in Golden Gate Park since April 9, and it’s still on for Saturday and May 14. I haven’t been to this event, but it sounds great. San Francisco Nature Education says, “Come experience the excitement of these four-foot-tall birds with six-foot wingspans. Observe adult great blue herons with their chicks…Naturalists and interns will be stationed at the observation site with spotting scopes, ready to offer views into the nests and answer questions.” There are guided tours from 10:30 a.m. till noon—follow the signs to the Boathouse. Cost is free for the observation area, $10 donation for a tour. For more information: http://sfnature.org/programs/heron_watch.html.

And speaking of chicks, there are Canada goslings down at the waterfront—the above photo is from last Sunday.