DANGERS HUMMINGBIRDS FACE
By Jon & Shani Friedman
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.
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."
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.
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.