Tripping the Light Fantastic

When I set out to write about a species, I start with “What is interesting about this species?”  With hummingbirds, though, what isn’t interesting about them?  The smallest of all birds, most of the hummingbirds seen in California weigh between 0.1 and 0.3 ounces (~2.5 – 4 grams) or less than 5 original M&Ms.  Probably their most striking characteristic is their unique and extraordinary ability to hover in the air as well as fly forward, backward, side to side, and even upside down for short distances.  They have very long tongues that can extend far beyond the tips of their bills, unlike most other birds except woodpeckers.  Their bills are uniquely designed to extract nectar from deep within tubular flowers.  Contrary to early thinking—that a hummingbird’s tongue uses capillary action to suck up nectar—recent research has shown that its tongue acts as an elastic “micropump.”  The two long, skinny tubes along the sides of the tongue flatten as it reaches to a flower, storing elastic energy; when it contacts nectar, the top of the tongue reshapes, drawing the nectar through the now-expanded tubes much more quickly (a mouthful 20 times a second) than capillary action could (5 times a second).  But not even hummingbirds can live on sucrose alone.  Small insects such as gnats and aphids as well as tiny spiders also make up an important part of their diet, providing protein to supplement the sugary high of nectar.

The 17 species that breed in the U.S. and Canada represent only about 5% of the more than 320 hummingbird species in the world.  (Actually hummingbirds are found only in the western hemisphere.)  California hosts four breeding species:  Anna’s, Allen’s, Black-chinned, and Costa’s Hummingbirds.  By far the most widespread in California is Anna’s Hummingbird.  In all plumages, the body shows a bronzy green above and gray or gray-green below.  The male’s throat, face, and crown flash an iridescent rose, copper, or gold, depending on the light; in bad light, the entire head just looks dark.  Adult females and immature birds display darkly beaded throats and a smattering of iridescent rose-colored feathers, usually in the center of the throat.  The male’s voice sounds like a cross between a squeak and a sizzle.  A displaying male also spreads his tail briefly to generate a high-pitched “pop” at the bottom of his showy dive, which can climb as high as 130 feet in the air.

Few birds have taken advantage of man-made surroundings more completely than Anna’s Hummingbirds. They breed widely over San Diego County, avoiding only a few parts of the desert. But they favor the coastal lowland and lower foothills.  In their range, Anna’s rank as the most abundant hummingbirds in gardens and at feeders.

In San Diego County, most Anna’s Hummingbirds nest mid-February to early June, although some in the coastal lowland start as early as January.  (If you’re thinking about trimming up bushes or trees now, consider that a hummer may already be nesting there.)  Regardless of species, a male hummingbird’s role in breeding is quite clear—mate with as many females as he can and then spend the rest of his summer days defending food sources for himself (or just get outta town toward more southerly climes, for those breeding in the far north such as the Rufous Hummingbird).  Females raise the young alone, building tiny thimble-sized nests of thistle and dandelion seeds, fur, feathers, and rootlets; small bits of bark or lichen serve to camouflage the nest.  Spider webs provide the stretchy glue for these components, allowing the tiny nests to expand as the nestlings grow.  Eggs (almost invariably two) are about the size of a small jelly bean.  The young hatch after 16 - 19 days and leave the nest around 20 days after hatching.  Fledglings depend on the mother for one or two weeks after fledging, although youngsters have been seen eating at feeders as soon as 10 days after leaving the nest.  A female can raise two or three broods a year.

Anna’s scientific name, Calypte anna, derives from Greece and France.  Calypte (“veil, hood”), from Greek kaluptre, refers to the male’s iridescent gorget, face, and crown, with the appearance of an elegant veil.  Both the species and the common names (Anna) honor Anna de Bell Masséna, a French courtier, who possessed the original specimens.  Finally, “hummingbird” arises from the buzzing wingbeats.

Hummingbirds fly so fast and nimbly that they have very few natural predators.  Yet one of the most fascinating, surprising, and perhaps creepy is the praying mantid (a.k.a. praying mantis).  Researchers found that large species such as the Chinese mantid—up to four inches long—were the most avid avivores, with females responsible for nearly all the bird-killing.  Sometimes a mantid will feast on the bird’s flight muscles along the keel (breastbone). But more often it goes for the head, especially the brain. (“Hummingbird brain—it’s what’s for dinner.”)  Although most adult mantids have wings, they often choose a slow, stealthy amble through vegetation or a patient stalk-and-wait approach.  (I’ve spotted them late in the summer, lurking near or even on our hummer feeders.)    They can also jump unerringly. Slowing down high-speed video, researchers found that bending its abdomen and making an intricate series of twists and turns with its legs ensure that a mantid makes a flawless landing on even an absurdly challenging target such as a pencil held vertically. The abdomen’s bending proved especially critical. When the researchers used a glue to stiffen the abdomen, the mantid couldn’t curl it properly and the insect invariably missed—sometimes even face-planting on the target and plummeting to the ground.

And in some world, somewhere, somehow, a hummingbird smiles.