Birds on the Defensive
Story by Bryan Pfeiffer
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-
BIRDS in focus
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.
A theatric (and melodramatic) killdeer pulls the old broken-wing trick in hopes of luring
an intruder away from the nest.