Birds in Focus: Birds on the Defensive

Birds in Focus: Birds on the Defensive

A theatric (and melodramatic) killdeer pulls the old broken-wing trick in hopes of luring an intruder away from the nest. Photo by Audrey / Flicker CC.

As a birder for nearly 60 years, I’ve managed to enrage a few nesting birds. Arctic terns in New Brunswick once drew blood from my scalp. Canada geese in Ohio charged and hissed at me. And a northern goshawk here in Vermont nearly knocked me down at the edge of a spruce bog.

Presented with human interlopers, birds basically have three options for protecting eggs or young: fight, flee, or fake it. They rarely fight. Most flee – they do have wings, after all. But the fake-out features some of the most crafty and bizarre behavior.

The ruse typically involves blatant deception – a “distraction display” – to lure a predator (or an innocent birdwatcher) away from a nest. Killdeer, our most common plover, is well known for the broken-wing trick. A bird crouches, extends, and droops its wings (sometimes flapping to beat the ground), and walks away while issuing a plaintive call. As it performs, the killdeer looks back at the intruder over its shoulder and fans its tail to display a rufous rump, a nice target for a predator.

If they gave out Academy Awards for bird performances, the killdeer would win for over-acting. But that’s the point. The maternal defense of young is a force of its own, and ground-nesting birds with exposed nests have few other options but sleight of wing.

A ruffed grouse with chicks will strut at your feet, fanning its tail and ruff, while its young scurry for cover. Sometimes she’ll charge or lunge at you as well. In Arizona, a pair of Montezuma quail, rare and reclusive and a prized sighting among birders, emerged from tall grass to sashay at the feet of my pals Mike Blust and his brother Barry for about 30 seconds (while I was sidetracked photographing butterflies). When I finally caught up with Mike and Barry, it was as if Bigfoot had emerged from the woods for a square dance.

Some distractions are more sophisticated. Killdeer and other plovers perform “false brooding” – settling down as if to incubate a clutch of eggs that isn’t there. On the prairie, when a grazing animal approaches, the killdeer also executes the “ungulate display.” With wings spread, it raises and fans its tail, ruffs its body feathers (presumably to look menacing), and charges or lunges at the cloven intruder (an act I can only hope to see some day between bird and buffalo). Yet another trick is the “rodent run,” performed notably on open Arctic breeding grounds by the purple sandpiper, which fluffs its feathers, scurries like a small mammal, and even issues squeaking calls in the act of luring a predator from its nest.

Songbirds generally don’t resort to these kinds of antics, although I’ve seen mousy, scurrying behavior among marsh-nesting sparrows. And an otherwise stealthy female ovenbird, a ground-nester, once walked right at me in a northern hardwood stand, then turned and strolled away as the male sang loudly from the branches above. I watched long enough to see her return to her eggs in the pair’s domed, oven-like nest. These displays do entail some internal conflict for the birds: the fake-out adaptation versus the nesting instinct.

Among other birds up in the trees, the defense of a nest varies from aggressive to acrobatic. Kingbirds take on hawks in flight, pecking at them from above. Tree swallows swoop on intruders and get close enough for you to feel the breeze from their wings on your face. When a pair of chipping sparrows, yielding no ground, once went berserk in shrubs beside a spruce, I knew I had inadvertently gotten too close to their nest.

Turkey vultures are reported to regurgitate something awful on intruders, which I suppose amounts to either a fourth category of nest defense or just dirty fighting.

Witnessing these sorts of displays has given me some of my most enjoyable times in the wild. Black bears, timber rattlesnakes, the panoply of biting insects, a bull moose in rut – I’ve faced them all in these northern woods, yet I fear nothing more than a goshawk at a nest. Then again, I’ve never been barfed on by a turkey vulture.

Bryan Pfeiffer is an author, wildlife photographer, guide, and consulting naturalist who specializes in birds and insects. He lives in Montpelier, Vermont.

 
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