Sunday, July 20, 2008

Li'l Red Devils

Rufous Hummingbird
Photo by David Powell

They’re Baaaack! All summer long, up until now that is, the two species of hummingbirds that nest in the Jemez Mountains have maintained a certain decorum in their daily activities with only occasional territorial squabbles. All that changes in the blink of a night, when the brash newcomer with the extremist lifestyle arrived on the scene in early July, confidently aggressive in his bright orange-red body, much like Lightning McQueen in the recent movie “Cars”. The “Ka-chow” of Lightning when he flashes his stickers is replaced by the time bomb-like “tick-tick-tick-tick” of the male rufous hummingbird as he twitches his head from side to side alertly watching and waiting. Suddenly, no feeder is safe from the stealth attack of Attila, the Hum, as he stakes out his favored feeder, and jealously guards it from unwary intruders.

The tiny rufous hummingbird breeds farther north than any other species of hummingbird, into southern Alaska and far from the equatorial tropics in which its ancestors evolved. If measured by its diminutive body length, the species has the longest known avian migration. Although the Alaskan breeding season is short, it has the longest day-length seen by any hummingbird. In fact the day length exceeds the needs of this bird, which requires 5-6 hours of rest each night.

Males breed with as many females as possible, and their only contribution to the reproductive success is sperm. Their elaborate courtship flight is described as a complete oval, which they pursue repeatedly in the presence of any female. I found one intriguing description of an individual attempting to impress a female with his prowess and superior physical attributes. After climbing to a great height above the female perched near ground level, the male reversed heading after entering a dive and then leveled out after passing the female. He uttered a series of short dit-dit-dit-deer calls increasing in pitch, followed by a few dull “plops” from using his tail feathers as a dive-brake. Very impressive, I’m sure. Another tactic is called whisking, in which the male flies rapidly back and forth at a consistent level in front of the female, much like a whisk broom. Perhaps this tactic wears down female resistance by its endless repetitions. When I consulted the references for actual mating activity, I found only a brief paragraph which stated, “After the dive display, a female joined the male in a swinging flight, which he thought included actual mating, but he was totally unable to see the birds except as a blurred streak of color. Further study needed.”

The nest is constructed by the female alone, who also incubates the eggs, and provides all sustenance for her young. Nesting in the far north, it’s a life on the edge for one of the smallest birds in the Western Hemisphere. Because the males finish their reproductive role early in the season, they are the first to arrive and that’s when chaos ensues in southern lattitudes. Males maintain territoriality at re-fueling stopover sites for 1-2 weeks at a time during migration. The more dense the flowers, or feeders, are the smaller the territory of individual males. One of the ways to reduce aggression at your feeder is to hang several feeders on opposite sides of the house out of the line of sight of an individual bird. However, often several territorial males set up a defense network around all of the feeders. Another trick is to make syrup with a mixture of one part sugar to three parts water for one feeder. The sweeter syrup may attract the rufous away from the other feeders. However, as part of the bigger picture of hummingbird conservation, the practice of hummingbird feeders is thought to have had a positive effect on hummingbird populations overall.

When the first Attila on the scene has enough fat reserves, he will move on, only to be replaced by a later arriving male, and then the females and juveniles. Soon, they also will be joined by the Calliope and Broad-tailed Hummingbirds that nest farther north as well. Experts recommend leaving your hummingbird feeders in place until about two weeks after the last hummingbird observation, or until about October 30 in this area. That last remaining feeder may mean the difference between life and death for America’s smallest bird, the last one to depart from his Alaskan summertime residence.

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