Nature Obscura. Kelly Brenner
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use their keen eyesight to find tiny insects hidden on branches, in the bark, or under leaves. These protein-rich morsels supplement their diet and help provide a food source when nectar is scarce. Hummingbirds are also known to follow sapsuckers to consume the tree sap collected in wells drilled by the birds, as well as the insects stuck in the sap. In addition to nectar and insects, they must drink up to eight times their own weight in water each day.
Without watching for him, I heard a slight chirp and knew that he was back. My eyes caught a flash of red and a blur of wings as the bird zipped up to within a couple inches of my face, a pane of glass separating us. He quickly surveyed for danger, looking at me with tiny eyes. I held myself motionless, and he seemed content flitting down to the feeder I’d attached to the window. He deftly dipped his needlelike bill into the small red metal flower before quickly hovering backward to peer at me again. Now he seemed more comfortable as he moved back to the flower, and this time he landed, grasping the edge of the feeder with minuscule feet—feet that are unable to walk, only sidle along a branch or feeder. The tiny green bird with the red head fed more leisurely, and yet even at leisure he moved unnaturally fast. All his body movements were jerky, even the gulping of his throat seemed quick, almost desperate. The tongue of the Anna’s is split at the end like that of a snake; the two halves each contain compressed tubes, but once the tips reach the nectar, the tubes open, drawing the fluid in. This male eventually removed his long bill from the flower, looked around, uttered a high squeak at seeing a competitor, and flew off after it faster than my eyes could follow.
Adult birds are much larger than I’d expect given their weight. When it’s cold outside, I’ve regularly noticed these fluffy little ping-pong balls perching in our tree branches. Though they lack the downy layer that many other birds possess, they puff up their feathers to act as insulation, keeping pockets of warm air inside, while the outer feathers act as a barrier, keeping out rain, snow, and the cold.
Feathers alone aren’t enough to survive the cold nights, so the birds build up their body weight during the day by constantly feeding, and they fill up their crops—a pouch many birds have and use for temporarily storing extra food—before it gets dark. The stored food, both as fat and nectar from the crop, is slowly digested at night; hummingbirds make it last. On cold nights hummingbirds can enter a state of torpor, which is somewhere between sleeping and hibernation. While in torpor their body temperature goes down to about 55 degrees and their heart rate drops to 50 beats per minute—in stark contrast to their usual 250 beats per minute at rest. To further help them survive the cold, they may roost next to porch lights or chimneys, human-made places that emit warmth during the night.
In winter the female birds coming to my feeders may very well be carrying eggs, although to my eyes they look the same as always. Anna’s eggs are about the size of peas and are usually laid in pairs. Tiny, but taking the female’s body size into account, they can be as much as 12 percent of her weight when they’re laid. As a comparison, my daughter was less than 5 percent of my body weight when she was born. In Seattle, Anna’s nest as early as February, a full month before our other breeding hummingbird, the rufous, even arrives. While the rufous is migrating hundreds of miles north from Mexico, our Anna’s are busy incubating their eggs, sometimes while covered in snow, or being pelted with rain or wind. For up to three weeks they suffer through this, alone.
Anna’s are single mothers—they build the nest, lay eggs, incubate, and feed their chicks each on their own. The nest is no larger than a golf ball and is very hard to find, despite being commonly located in backyards and parks. While the inside is lined with fluffy seeds and downy feathers, the outside is covered in camouflaging lichens and moss, the entire thing bound together with webs stolen from spiders. This tiny nest is masterfully constructed to be hidden and very warm. One study found that hummingbird nests have a thermal conductivity on par with that of polar bear fur.
Chicks hatch blind with pink, naked bodies and underdeveloped bills. The mother feeds them by poking her long bill down the chicks’ stubby bills and regurgitating nectar. The chicks have relatively well-developed crops, which are disproportionately large and can bulge out of their necks impressively when full of regurgitated food. The naked, fattening chicks are utterly defenseless against weather and predators.
A mother grizzly has nothing on a mother Anna’s when she’s defending her nest. Females have been seen driving off and buzzing at birds many times their own size, including jays, crows, and hawks. Even humans considered to be a threat have been harassed by tenacious hummingbirds. It’s for good reason: nests suffer a high mortality rate, and jays and crows are guilty of picking chicks from nests. The mother herself is not always safe, and while she is feeding on nectar she is at risk from outdoor cats. The one thing she can’t do much about is the weather; storms and frosts can increase the mortality of adult and chicks alike.
There are rarely two hummingbirds at either of my feeders at the same time. The male that visits my feeder in the front yard does not tolerate any other hummingbirds. He keeps a close eye on any movement around his territory, and I often see him leap up from the feeder and speed off in pursuit. The rest of the time he’s sitting in a small tree nearby watching for intruders or potential mates. I frequently hear a series of squeaky chirps while sitting at my desk, and I know without even looking that there’s yet another hummingbird dispute right outside the window. And although I haven’t witnessed an actual fight, the tussles can and do get physical. Usually the disputes are settled by chases or dive displays.
Late one winter I was in the yard checking for signs of life in my plants. While looking at the gooseberry buds I heard a high-pitched, loud chirp. I looked straight up, very high in the sky, and saw a speck, so small that it may have been a spot in my vision from looking at the bright sky. But then it moved impossibly fast, straight down toward the apple tree on the other side of the fence. I heard the loud chirp again and finally made out the tiny figure of a hummingbird. It flew in an arc back up to just above the tree and stopped briefly to utter its chittering song; then it flew up like a rocket to start the routine again. Instead of watching the male, I turned my eyes to the bare branches of the tree because I knew a female was likely perched there. The male dove to impress her, hopefully enough to encourage her to mate. Sometimes the male uses it to deter competitors, but usually he saves the display for females.
The male may have impressive aerial skills and a fancy appearance, but since I began watching and being involved in the lives of my visitors, I have developed a great deal of respect for the ferocity and endurance of the single mothers. Without my realizing it, over time, the lives of these birds right outside my windows have become woven into my own as we both go about our daily routines together, separated by a pane of glass.
The Patina of Time
To a naturalist nothing is indifferent; the humble moss that creeps upon the stone is equally interesting as the lofty pine which so beautifully adorns the valley or the mountain . . . .
—James Hutton, Theory of the Earth
Before I climbed up onto the railing outside our back door, I first looked around to see if any neighbors were in their yards or walking down the alley. When the coast was clear, I hauled myself up and stood on the railing before stepping across the gap to the roof of our detached garage. I scooted on my backside across the roof, where I lay down, stretched out across the asphalt shingles.
Conventional wisdom says that moss on your roof is bad and that it’ll make the shingles too wet, causing them to rot, or that the roots will lift up the shingles, leading to water damage. A mossy roof is considered an eyesore in the city and better suited to a rustic old cabin in the woods. But I’m curious and tend to question the status quo.
As I lay on my belly, I studied the rows of moss organized neatly along the shingle edges. The moss grew in tiny clumps, no more than a half-inch wide at most. The little green tufts with silver tips were nothing short of adorable, a miniature landscape growing far above the ground. I saw no shingles being forced up into the air, and when I pulled a couple clumps off, they came up easily, without a fight, leaving nothing behind. I couldn’t see any damage at all. As I studied the moss, poking and prodding at it, I began to question whether it really needed to be removed.
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