A route of evanescence

A Route of Evanescence
With a revolving Wheel –
A Resonance of Emerald
A Rush of Cochineal –
And every Blossom on the Bush
Adjusts its tumbled Head –
The mail from Tunis – probably,
An easy Morning’s Ride –

EMILY DICKINSON

First light. From my chair on the front porch I can hear a ruby-throated hummingbird (Archilochus colubris, the only hummingbird species we have here) just around the corner of the house. I get up and look: it’s a male, filling up on nectar from the comfrey flowers. Out of all the more showy flowers in my garden, it’s the nondescript, reddish-purple comfrey that’s drawing the hummers right now. Watching the crimson-throated male thrust the tiny sword of his bill into the flowers’ upside-down cups, I think of one of the Spanish words for hummingbird, picaflor.*

Contrary to popular belief, a hummingbird’s bill is nothing like a drinking straw. It opens just wide enough to allow the bird to lap up nectar with its brushy-tipped tongue, which zips in and out at the rate of thirteen times per second. The hummingbird tastes little of the flowers, other than their relative concentration of sugar, and he smells nothing at all. His vision, however, is acute. And anecdotal evidence suggests that hummingbirds have long memories, as well, in some cases appearing to form strong bonds with human benefactors and returning to visit them throughout the season and even in subsequent years.

A long memory would be a highly adaptive trait for a creature whose survival depends on being able to find reliable sources of nourishment from food sources that change by the day and even by the hour. One wonders how many details of his thousand-mile round-trip migrations he can recall from one year to the next. Imagine what the mental map of a hummingbird might look like: bright jewels of color like beads in a rosary stretching from Pennsylvania down through the Appalachians to Georgia, west along the Gulf Coast and then south through Mexico to Guatemala, Honduras, Nicaragua, even Costa Rica.

The male rubythroat returns twice more to the comfrey during the half-hour I’m out on the porch. I recall what an ornithologist recently told a meeting of our Audubon chapter concerning hummingbirds: the males are smaller than the females, just barely above the energetic limit for warm-blooded creatures, below which it isn’t possible to eat quickly enough to stave off hypothermia. And they expend so much energy on their spectacular, U-shaped mating/territorial flights and in fighting with other males – chasing, jabbing with their bills, striking with their feet – that they have few fat stores left over to keep them alive during the cool spring nights. Many of them don’t make it. It’s not unusual for female hummingbirds to outnumber males four to one by the end of their first breeding season.

Hummingbirds are unique to the New World, and occupied a prominent position among the marvels described by the first European explorers. It occurs to me that the Aztecs were well justified in associating the hummingbird with their kamikaze-like warrior cult of death and flowers – especially that crimson flower in the chest, whose sacrifice they thought necessary to feed the sun. A ruby-throated hummingbird’s heart can beat 1,220 times a minute. It accounts for some 2.5 percent of the bird’s total body mass, which means that in proportion to its size, the hummingbird has the biggest heart of any member of the animal kingdom.

Ironically, for a creature still associated with male prowess in some parts of Latin America, the male hummingbird has no penis whatsoever. He fertilizes the female merely by touching the tip of his cloaca to hers for a fraction of a second; his relationship with flowers is vastly more prolonged and solicitous. During the non-breeding season, the sex organs of both the males and the females shrink to a tiny fraction of their active size to make the birds better fit for their lengthy migrations, like backpackers chucking every ounce of unneeded gear. For the same reason, the female makes do with a single ovary.

They leave for Central America when the nighttime temperatures here are barely above freezing, flying low to the ground to avoid cooler temperatures aloft. Just before and during migration, their diet becomes largely insectivorous as they stock up on fats and proteins, often doubling their body mass. In the tropics, rubythroats may continue to rely much more on insects than on nectar. But even here, a sizeable proportion of their ordinary diet consists of small insects found in, on or in the vicinity of flowers, as well as pollen, which they play a major role in spreading from plant to plant. Their ability to key in on bright spots in the landscape probably allows them to quickly locate their favorite kinds of insects during migration. Their breeding range maps closely to the range of eastern deciduous and mixed deciduous-coniferous forests – a fact which may also have direct dietary relevance, since they sometimes rely on tree sap when no suitable flowers are in bloom. Their arrival back north (late April to early May in Central Pennsylvania) seems to be timed to take advantage of sap flows in birch trees “tapped” by the yellow-bellied sapsucker, though doubtless the presence of small insects also plays a role.

It always boggles me a bit to think about pollination: one species relying on another, completely unrelated species to perform what is, for us, the most intimate of acts. The variously curved and elongated bills of hummingbirds are well adapted to flowers with deep throats; their co-evolution suggests an effort on the part of the flower to exclude insect pollinators, whose senses and memory may not be up to the task of properly cross-pollinating between widely scattered individuals or populations. At least nineteen species of plants in North America have co-evolved with hummingbirds as a primary pollinator, including trumpet creeper, beebalm and jewelweed. With their bright, iridescent colors, hummingbirds seem more than a little like flowers themselves – or rather, like a flower’s wet dream.

But it’s no surprise that birds with such highly developed visual cortexes would wear bright colors; the primary audience for a male hummingbird’s aerial display is, of course, another hummingbird. From where I sit here at my writing table, looking out my front door, I am often treated to a partial view of this display, probably from the very same bird I saw at the comfrey this morning. He hurtles back and forth along a hyperbolic arc like the pendulum for some invisible, mad clock, his metallic green plumage flashing in the sun.
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*The usual, more literary word – as in the first of the two Lorca poems I translated yesterday – is colibrí­. But in my brother Mark’s Birding Honduras: A Checklist and Guide, there are neither picaflores nor colibrí­s, but gorriones and gorrioncitos – words otherwise applied to sparrows. In other Spanish-speaking countries, the term chupaflor – sucks-the-flower – may be used instead of picaflor (pecks-the-flower). And in Brazil, a hummingbird is beija-flor, kisses-the-flower – arguably the most appropriate name of all.

Primary sources for this essay included: T. R. Robinson, R. R. Sargent and M. B. Sargent, Ruby-throated Hummingbird, No. 204 in the monograph series The Birds of North America, edited by A. Poole and F. Gill, The Academy of Natural Sciences and American Ornithological Union, 1995; Alexander F. Skutch, The Life of the Hummingbird, Crown Publishers, 1973; and the terrific (if poorly designed) website for Operation RubyThroat: The Hummingbird Project.