Home & Garden Columns
I know: another corvid column. But bear with me. Every now and then I trawl the technical literature at the UC library, and this time I found a jay-and-crow story in the Wilson Journal of Ornithology that’s too good to keep.
You may have read about the clan of chimpanzees in West Africa who have been reported as using weapons to obtain their favorite meal of bushbaby-on-a-stick—a step beyond previous observations of tool use. Now Russell Balda has documented an apparent case of weapon use by not just one, but two species of birds—a Steller’s jay and an American crow. Balda, not just any feederwatcher, is an authority on the pinyon jay and runs the Avian Cognition Laboratory at Northern Arizona University in Flagstaff, a site of cutting-edge research into corvid intelligence.
A word on nomenclature: yes, it’s “Steller’s,” not “stellar.” Everybody seems to get that wrong. Although this crested black-and-blue jay could be said to have a certain star quality, it was named for its discoverer, the 18th-century Russian naturalist Georg Steller. Steller, one of the few survivors of the ill-starred Bering Expedition to the North Pacific, had a short and tragic life, and the least we can do in his memory is get the names of his jay, his sea lion, and his eider (among other species) right.
So Balda, on an April morning three years ago, is in his office outside which is a meter-square feeding platform. A crow is on the platform eating sunflower seeds. Two jays—maybe a pair; it’s hard to tell with jays—land in a nearby mountain mahogany bush. The jays seem annoyed by the crow’s presence. One flies to the platform and scolds the larger bird, which fails to react. The jay feints toward the crow with its bill; the crow feints back. The jay flies up to the roof of the building, then divebombs the crow. The crow keeps eating. End of Round One.
Then the jay does something remarkable. It goes back to the mountain mahogany and breaks off a twig from a dead branch. Holding the twig in its beak, pointed end forward, it returns to the feeding platform and lunges at the crow. It’s a near miss. The crow lunges in its turn, startling the jay, which flies up and drops the twig onto the platform.
And the crow picks it up, again pointed end forward, and thrusts it at the jay. Whereupon the jay on the platform and its partner in the bush both fly off, pursued by the twig-carrying crow.
Now, there’s a considerable literature on tool use in birds of the crow family, with examples from the Eurasian common crow and the blue jay of eastern North America, among others. Tool-making reaches its pinnacle in the New Caledonian crow, which constructs (you can’t really say a handless creature manufactures) various types of tools to extract insect grubs from rotten wood, and carries the tools around with it from foraging site to foraging site. Tool use seems to correlate to brain size, and corvids have the largest brains (in proportion to body weight) among birds, outscoring even parrots.
Weapons are another story, limited to anecdotes about ravens and crows dropping objects on humans that got too close to their nests.
But Balda is convinced that weapon-making and weapon use is what he saw: “Behaviors that are classically associated with lance or spear use were observed in this bout. The jay first selected and prepared an object that could readily be used as a spear, and then lunged at the crow with the spear … The crow retrieved the twig and possibly used it against the jay. The current report may be the first incident of a bird holding an object and using it in a weapon-like fashion during an aggressive action against another bird.”
At this point nothing much a crow or jay could do would surprise me much, with the possible exception of text-messaging. If you have Steller’s jays or western scrub-jays at your own feeder, they’ll obviously bear watching.