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Photo by Douglas Everett |
Those of us who love hummingbirds do so for many reasons.
Their appeal is irresistible. We marvel at their magnificent iridescent
coloration, their unique flying abilities, their courtship and mating
displays, the female's excellent parenting skills, and their curiosity
and fearlessness of humans. We are all familiar with the saying "survival
of the fittest," but we seldom think that hummingbirds have predators
and other dangers that they must face.
Very few of us have ever encountered a situation in nature
that was life threatening to hummingbirds, but each and every day of
their lives hummingbirds must avoid a host of potential dangers. In
the U.S. there are no natural predators who specialize in hummingbirds.
But in Costa Rica, there is one - a tiny hawk of the rain forest (Accipiter
superciliosus fontanieri). These tiny hawks capture perched Costa Rican
hummingbirds within the hummer's territory by sudden attacks, as opposed
to aerial pursuit which is the more common method employed by most hawks.
This unique approach to hunting is well suited to the small hawk, as
hummingbirds are such agile and superior fliers that snatching them
in the air would be almost impossible.
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Photo by Douglas Everett |
Orioles, flycatchers, falcons, and small hawks (such as
the Sharp-shinned hawk) are the most adept predators of hummingbirds.
One report from New Brunswick, Canada involved a male Baltimore oriole
preying upon a male Ruby-throated hummingbird. The "male hummingbird
hovered in front of a blossom within about one-third meter of the male
oriole. The oriole turned, pounced, and caught the hummingbird in its
beak. It then flew to a nearby branch and held the hummingbird down
with its feet and pecked at it violently until feathers flew from it…When
I picked the little bird up, it was dead."
At Cave Creek, near Portal, Arizona, a Brown-crested flycatcher
was seen preying on a male Rufous hummingbird at a feeder. "The flycatcher
swooped down from a perch it had used for several days near the feeder.
The flycatcher extended its wings just prior to midair contact with
the hovering hummingbird, and knocked the small bird to the ground.
The flycatcher quickly picked up the stunned hummingbird in its beak
by one wing and flew to a branch overhanging the feeder. The Rufous
dangled from the flycatcher's beak. Repeatedly, the flycatcher knocked
the hummingbird against the branch with violent side to side motions
of its head. The flycatcher then flew with its prey out of my vision
to a distant tree."
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Photo by Douglas Everett |
Hans Peeters of the Museum of Vertebrate Zoology, Berkeley
observed a male Anna's "perched on a dead branch…preening. A male Sharp-shinned
hawk flew rapidly toward the hummingbird. The hawk dashed along about
one foot above the ground, apparently using the brush as a screen. When
it was approximately opposite the hummingbird, it suddenly swooped up
over the bushes and seized the Anna's. In doing so the hawk barely checked
its flight, and flew on to a stand of bay trees, where it disappeared."
Ernst Mayr of the Museum of Comparative Zoology, Harvard
reports this incident. "I was watching through a window of a Ruby-throated
hummingbird feeding on zinnias at Lyndeborom, New Hampshire. Suddenly
a kestrel plunged down to the flowerbed about a foot away from the hummingbird
and with a flash-like sideward movement caught the hummingbird with
its feet. The hawk immediately rose steeply and was already about 100
feet high when, within a few seconds, I had reached the outside." With
so many documented sightings of aerial attacks against hummingbirds
by larger birds, it is fair to assume these attacks happen far more
often than we have observed. Theoretically, this could be why most hummingbirds,
especially females, have a lot of green on their backs. Green blends
with the vegetation below, making it more difficult to be seen by predators
from above.
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Photo by Douglas Everett |
While green coloration may provide camouflage from predators
overhead, amphibians lurking in ponds strike from below. The following
account comes from the American Museum of Natural History's Southwestern
Research Station in the Chiricahua Mountains. "…the hummingbird flew
down and landed at the edge of the water about 30 feet in front of us.
Apparently the bird sought a drink; it dipped its mandibles into the
shallow water once after landing. Immediately a frog of unidentified
species leaped from the grass near the water line struck the bird a
hard blow and knocked it into deeper water. The bird struggled in several
inches of water as the frog followed up its initial attack by seizing
the bird and diving with it into a bed of submerged vegetation. Neither
bird nor frog reappeared on the surface."
Many instances of frog predators, particularly leopard
frogs, have been documented. More attempts than actual captures have
undoubtedly been observed. A Canadian naturalist once saw such a situation.
While watching a hummingbird a frog jumped out of the water and the
hummer disappeared. He thought perhaps the frog might have gotten the
small bird. "With the help of boys the frog was captured and killed.
As the boys dissected the amphibian, Moncrief filmed the hummingbird
body's recovery."
Hornets and yellow jacket wasps have been known to prey
upon hummingbirds as well. This is particularly true of nestlings, which
are easier prey than the adults are. The praying mantis has also been
observed taking hummingbirds. Snakes and lizards have been known to
capture hummingbirds, too. Here in the southwest, roadrunners are a
threat to hummers. Sally Spofford, of Portal, Arizona has provided reports
of roadrunner attacks on Black-chinned hummingbirds. Several reports
from New Mexico also demonstrated the roadrunner's taste for both hummers
and their nests.
Spider webs are noted as fatal attractions to hummingbirds.
In their quest for a favorite food, baby spiders, hummingbirds sometimes
get caught in the web of a spider. One observer noted: "In its struggle
to free itself from the spider web it called frequently, attracting
another Anna's which hovered nearby." For forty minutes it tried to
free itself, all the while becoming further entangled and showing increasing
signs of exhaustion. The observer then cut the hummer from the spider
web and released it.
Mid-air collisions with bees and wasps sometimes result
with the insects impaled on the hummer's beak. If the hummer cannot
quickly get the insect off, the insect may dry in place and prevent
the hummer from being able to open its mandibles to feed.
Hummingbirds face all of these dangers and more. The most
significant hummingbird peril is one that could be curtailed or could
become catastrophic. It is the loss of habitat to human ventures that
is increasing at an alarming rate.
This article was reprinted from The Wild Bird Store Newsletter,
Vol.2, No.8, October, 1994.
