Pelican-Watching in San Francisco

Fog over Golden Gate Bridge, copyright 2009 Christine Petersen

(Author’s Note: This is a duplicate posting of content found on my homepage. Please visit for regular updates to the blog and information about my work.)

I’m standing on the coastal trail just west of San Francisco’s Golden Gate. Fog obscures most of the famed structure, though now and then a blazing patch of red is revealed as a gust of wind pushes aside a corner of the low-lying cloud. My goofy grin and slightly elevated heart rate are reminiscent of the symptoms I used to experience on a promising second date. I indulge the emotions, for they are familiar and sweet. In a way, this city is like a long-lost lover. Although my new sweetheart—Minnesota—is also full of charms, some part of my heart will always remain here.

The Golden Gate Bridge is an iconic structure known around the world, and I never tire of this view. Yet there are countless more delights to be found across the landscape leading into this narrow, rocky passageway. Craggy cliffs, hidden beaches, and patches of woodland are revealed to those who explore the ecotone where land meets sea. Every stretch of the San Francisco coastline offers breathtaking views, and crowds are often minimal.

Brown pelicans, copyright 2009 Christine Petersen

If asked to choose a mascot to represent this landscape, I’d find few rivals worthy of the brown pelican. To the inexperienced observer this might seem an odd choice. Weighing up to eight pounds, with a wingspan greater than 7 feet and a curving neck that culminates in an improbably long, hooked bill, brown pelicans look like make-believe creatures from a child’s storybook: gangly, disproportionate, and comical. Yet airborne pelicans are the epitome of grace—flapping with slow ease; making fast, steep plunges in pursuit of fish; flying in long, curving formations that follow the breaking lines of waves.

In the 1820s and ’30s, while traveling across the nation to study and paint avifauna, John James Audubon had many opportunities to observe brown pelicans. He found them to be “one of the most interesting of our American birds,” and had this to say about pelicans on the wing.

“The flight of the Brown Pelican, though to appearance heavy, is remarkably well sustained, that bird being able not only to remain many hours at a time on wing, but also to mount to a great height in the air to perform its beautiful evolutions. Their ordinary manner of proceeding, either when single or in flocks, is by easy flappings and sailings alternating at distances of from twenty to thirty yards, when they glide along with great speed. They move in an undulated line, passing at one time high, at another low, over the water or land, for they do not deviate from their course on coming upon a key or a point of land. When the waves run high, you may see them “troughing,” as the sailors say, or directing their course along the hollows. While on wing they draw in their head between their shoulders, stretch out their broad webbed feet to their whole extent, and proceed in perfect silence.”

Audubon was not alone in his appreciation of pelicans. Women of the nineteenth and early 20th centuries considered it the height of fashion to festoon their hats with feathers. Many bird species, including pelicans, were hunted to fulfill orders for the millinery trade. Pelicans were vulnerable to other threats, as well, including egg collection and hunting by fishermen who considered pelicans to be their competitors for fish.

Passage of the Migratory Bird Treaty Act in 1918 curtailed these forms of collection. Yet surveys in the 1960s showed that brown pelicans had all but disappeared from California. Only a small nesting population remained on one of the Channel Islands, off the coast near Ventura. The birds’ killer this time was almost invisible—carried on the wind and in water, hidden in the tissues of fish which the pelicans consumed. It was dichlorodiphenyl-trichloroethane—better known as DDT.

First synthesized in 1873, DDT was virtually forgotten until the 1930s when Swiss chemist Paul Müller discovered its effectiveness as an insecticide. In World War II DDT was applied to protect Allied troops from diseases spread by mosquitoes and lice. Dr. Müller won the Nobel Prize in Chemistry for his work, which was seen as a life-saving advancement in the fight against insect-borne diseases. After the war, and through the 1960s, DDT was widely used in agriculture and advertised as a safe treatment for household pests. Human health risks from the chemical were not immediately apparent, but evidence of environmental hazards soon began to mount. DDT has a long life in the environment, as do the products of its chemical breakdown, DDE and DDD. These chlorinated hydrocarbon chemicals move up the food chain from microscopic organisms to fish and thus to pelicans and other piscivorous birds. They accumulate in fatty tissues over time, so that larger and longer-lived animals—such as pelicans—accumulate proportionately greater chemical loads than smaller, shorter-lived species. Humans are also affected by this process, called biomagnification.

Biologist Rachel Carson reported the effects of DDT in her ground-breaking book, Silent Spring, published in 1962. She wrote about the sudden decline among populations of American robins and other ground-feeding birds after DDT was used to treat Dutch elm disease in many communities during the 1950s. Direct exposure to the insecticide caused many of these small birds to die immediately. But Carson was also concerned about long-term effects. She noted that for many years DDT had been sprayed along the Atlantic coast to combat marsh mosquitoes, and knew the effects on marine species, and reported in Silent Spring that “Fishes and crabs were killed in enormous numbers. Laboratory analyses of their tissues revealed high concentrations of DDT—as much as 46 parts per million.”

Carson knew that fish make up a significant part of the bald eagle’s diet, and extrapolated that by virtue of their long lifespan eagles and other fish-eating birds would store proportionately larger concentrations of DDT than small, shorter-lived marine animals. As a consequence, she wrote, “they are less and less able to produce young and to preserve the continuity of their race. (Carson 122)” Declines in the rate of bald eagle reproduction had already been observed. Carson felt certain DDT was to blame, though she could not explain how the chemical caused physiological damage.

Research in the late 1960s revealed the mechanism by which DDT affects bird reproduction. Calcium carbonate is the primary mineral component of eggshells, and serves as a crucial source of calcium for embryonic skeletal development. Calcium carbonate is secreted by the bird’s shell glands during egg formation. It is apparently blocked by the presence of DDE, a chemical that results from the metabolic breakdown of DDT. By the late 1960s, brown pelicans nationwide produced eggshells that were, on average, 20 percent thinner than in years prior to DDT use. Some populations of California brown pelicans were found to have shells only half as thick as normal. Brown pelicans build a stick nest on the ground or in a tree. The male and female of each pair take turns on nest duty, sitting on the edge of the platform and incubating the eggs beneath large, webbed feet. DDE-thinned eggs were delicate and susceptible to cracking under pressure, making pelican reproduction an abysmal failure.

Brown pelicans might have gone the way of their ancient dinosaurian kin. But thanks to a 1972 ban on DDT and protections under the U.S. Endangered Species Act, extinction of the species was averted. The intervening decades have seen a slow but sustainable recovery of brown pelican populations, significant enough to lead the U.S. Fish and Wildlife Service in 2008 to propose delisting of all brown pelican populations from Endangered Species Act protections. That process was finalized on 17 November 2009.

On your next visit to San Francisco, tear your eyes from that big, beautiful bridge for just a few minutes. Watch instead the narrow valleys between cresting whitecaps, and look to the sky at hilltop level. Better yet, wend your way westward and south through city neighborhoods to China Beach, Lands End, or Fort Funston. It won’t be long before an undulating line of pelicans drifts in, skimming silently across the water or plunging-and-plundering in search of fish. Don’t be embarrassed if your heart starts to beat a little faster. It’s appropriate to be thrilled when you witness a miracle.

Golden Gate Bridge in clearing fog, copyright 2009 Christine Petersen


Head in the Clouds

Harvest Moon, copyright 2009 Christine Petersen

Autumn weather is as changeable as a teenager’s moods. On Sunday night a heavy bank of clouds rolled in just as the Harvest Moon began to peek over the eastern horizon. The low pressure system parked over our heads and remained in place for two days, bringing two inches of much-needed rain.

Wednesday dawned fresh and golden. By early afternoon warmer air had caused unusual cloud formations to build up. Altoculumulus undulatus clouds are named for their resemblance to rippling wave trains along the surface of the water. Also known as billows, these clouds form as the result of wind shear. Localized differences in wind speed and direction break up larger altocumulus clouds, reshaping them as narrow cloud-rolls. Billows may be ramrod-straight or form gentle curves, but are always evenly spaced in parallel rows.

I recall seeing billow clouds a few times in my childhood. Back then I found their symmetrical design a little frightening, reminiscent of the ribs of some skeletal sky-giant. As an adult I observe natural phenomena through the rational lens of science. Yet plenty of youthful imagination still tinges my view. Standing in the yard my eye was drawn to the straight line of those clouds, and for a moment I imagined having the ability to fly along that sky-path. But even as I watched, the clouds began to lose their structure—joining then stretching, thinning and breaking apart. Within 20 minutes, the sky was completely clear and blue. And I remained affixed to the ground.

Tentative sunlight at the terminus of the week brought local maple trees to the peak of color. While our neighbors began to spend evening hours raking, trees in our meadow and yard have steadfastly held on to their leaves. A golden glow fills the air at all hours, seeping through the windows and reaching my office as I work. As if I needed another distraction!

But this too shall pass. As I write this in the late hours of Friday night, the drying leaves of a pin oak outside my office window begin to rattle. The wind has picked up from the west. With it, capricious Autumn may bring the first snow of the season.

Announced by all the trumpets of the sky,
Arrives the snow
—Ralph Waldo Emerson, from “The Snowstorm”

Snowy meadow after October snow, copyright 2009 Christine Petersen

Actions Speak Louder

Yesterday I read a remarkable, true story about William Kamkwamba, a young man from Malawi, Africa. William was kicked out of school at age 14 because his family could not pay the $80 annual school fee. Instead of becoming dejected or angry, William began to spend time at the library. When he noticed a picture of a windmill, William got the idea to build one. He realized that the windmill could provide a little electricity and pump water, both of which were in short supply in his community.

Now in his early 20s, William has written a book about his experiences. This Wednesday, October 7, you can see him on The Daily Show with Jon Stewart. To learn more about William’s work or support his efforts, visit his personal blog. He is also a guest blogger on Huffington Post.

I’ve spent an undue share of my life feeling stuck in a rut, wondering how to achieve my dreams and find good, meaningful work. Sometimes thinking is the precursor to creative work. But let’s be honest. It can also be nothing more than fuel for the ego, an excuse to avoid trying the gifts we possess and doing the work we are meant to do. Ralph Waldo Emerson wrote, “Thought is the blossom; language the bud; action the fruit behind it.” I am so moved by this story of a young person whose curiosity and recognition of a need led him to act, despite scarcity of emotional or financial support.

May your dreams continue to bear fruit, William Kamkwamba!

Read Across America (or, William’s Solar-Powered Adventure)


The desert of east-central Nevada is lovely, cold, and deep. But as the first sunlight tinges thin clouds above, it’s time for William Grote to get moving. Quickly packing his belongings into the back of his Hauler, he hits the road. This three-wheeled bike looks a bit like an overgrown Mars Rover—and it’s got some of the same features. Wide tires enable the Hauler to traverse off-road terrain. And like the Rover, this vehicle carries a solar panel connected to a battery pack, which stores energy for later use. The battery powers an electric motor to assist the rider through challenging conditions, and also provides connections for AC power. (William’s pedal-power also contributes to battery storage.) The Hauler’s frame is designed to carry 500 pounds, in the form of passengers or cargo behind the recumbent driver’s seat.


William’s journey began at Hood River, Oregon, site of the Hauler factory. He left in early September, planning to follow the U.S. Bicycle Route System through the central United States to a final destination at Mount Pelier, Vermont. Total distance: more than 4000 miles—including an elevation change of 12,000 feet between the Rocky Mountains and the Great Plains.

This would be a profound personal journey under any circumstances. But William has added another component that also makes the journey relevant to communities through which he passes. As he travels, Williams will stop at local (usually rural) schools and other community centers. He sees it as a chance to educate about sustainability. In particular, William hopes to share the philosophy of cradle-to-cradle resource use, which looks at the full life cycle of a product. How can production be more efficient, use be more sustained, and disposal less prevalent? Asking children to consider these questions reminds them to think toward the future.


On this cold morning William will pedal uphill to a small school in Baker, Nevada. One teacher, four grades, a dozen students. Under the brightening desert sun all the kids, the teacher, and many parents—in fact, pretty much the whole population of Baker, NV—gathers and mounts their bikes. This annual event is called the Wheel-A-Thon. A snaking line of townspeople makes its ways eight miles southeast to the neighboring town of Garrison—which happens to lie just across the border, in Utah. William rides along, one of the gang today, his crazy contraption gathering sunlight that has slipped between billowing, white clouds. Turning around they retrace the route, arriving at the schoolhouse in time for lunch. William reads Dr. Suess’s The Lorax and discussion ensues. Then he’s off again. He’s got promises to keep, and miles to go before he sleeps.

As a supplement to his classroom visits, William has established a donation program through which he leaves books at every school. Houghton Mifflin has provided several dozen paperback copies of Curious George Plants a Tree for donation to primary classrooms. And Scholastic made library-bound copies of Solar Power (one of my books) available at a fifty percent discount. Individuals can support William’s effort by visiting at his website:

Check the BOOKS link to find titles for readers at the primary, secondary, and adult levels. Purchases can be made directly from the site; UPS has arranged to deliver them to William at designated pick-up spots along the route.

If you are interested in donating a copy of my book, Solar Power, the best way to do this is via PayPal. The link for this option is on William’s SPONSORSHIP page. He and I use donated funds to order these books directly from the Scholastic warehouse.

And if your town is along or near William’s route (which can be viewed in detail on his site), invite him to visit a local school or library! Click the spinning water pitcher icon to email William directly.

Information about Solar Power or other books by Christine Petersen is available at

Peddling Away Down the Road of Life

Raise your hand if you like to ride bikes!

Chances are, many of you responded positively to that question. If I could get everyone in the U.S. who purchased an adult-sized bicycle in 2008 to read this blog, there would be more than 13 million hands raised at this moment.

Early twentieth-century bicycles (from Wikimedia Commons)

Early twentieth-century bicycles (from Wikimedia Commons)

America’s love affair with the “dandy horse” goes way back. After its initial wave of popularity in the 1880s, the bicycle experienced a resurgence in the wake of the Great Depression. In 1936 the magazine Popular Science provided a summary of biking in the states. “Four million Americans now pedal along streets and highways,” revealed author John E. Lodge. “And, last year, factories in the United States turned out 750,000 machines.” As today, people rode for fun, exercise, and as a mode of transportation. Lodge reported that the craze had also swept Hollywood. “One prominent actor pedals ten miles between his home and the studio twice a day, rain or shine.” It was during this period that many urban bike trails were established. Bike technology advanced to include multiple-speed gear shifts, safety features, and conveniences such as softer seats and kick stands.

Bikes have never lost their appeal as a source of fun, entertainment, and exercise. But the past century has seen the automobile roll over every competitor as the number one form of transportation. In 1960 there were about 74 million personal passenger vehicles, trucks, buses, and motorcycles in the United States. Today that number has escalated to more than 250 million. To make this comparison meaningful, of course, we must factor in population change. According to the U.S. Census Bureau, U.S. population has increased by about 70 percent since 1960—from 181 million to 307 million. Meanwhile there has been a greater than three-fold increase in the number of vehicles on American roads.

But wait, there’s more! Changes in fuel economy during this half-century have been incrementally slow. Between 1960 and 1990 the average mileage (for all vehicle classes combined) crawled upward from 12.4 to 16.4. Corporate average fuel economy (CAFE) standards determine the mileage for passenger vehicles and light trucks, and they tend to represent the higher end of the mileage spectrum. Even so, the 25-year period beginning in 1980 saw only a 7 percent increase in fuel economy, reaching 24.8 mpg in 2000 and remaining near that level thereafter. New CAFE standards were passed in May 2009. By 2016 passenger vehicles must achieve 42 mpg and light-duty trucks 26 mpg. But poor fuel economy is only part of the problem. Data from the 2007 American Community Survey (a tool used to collect demographics between the 10-year national surveys) reveal that 76 percent of Americans drive alone in their cars to work. I’ll spare you the statistics on the gasoline consumption that results from this behavior—suffice to say that it’s a lot.

Because you’re savvy, I’ll bet you can predict the next fact. A single gallon of gasoline emits 19.4 pounds of carbon dioxide into the atmosphere. (The number is slightly higher for diesel.) Burning fossil fuels has been linked to climate change, but also to increasing rates of asthma and other respiratory conditions. Meanwhile, millions of Americans experience heart disease, stroke, diabetes, obesity, and the precursors to these life-threatening conditions. Why? Because we don’t get enough exercise.

The National Institutes of Health have a simple solution. To promote a healthier lifestyle, and to protect our environment, NIH recommends biking and walking. (You knew I’d come full-circle eventually, didn’t you?)

“The European countries with the highest levels of walking and cycling have much lower rates of obesity, diabetes, and hypertension than the United States. The Netherlands, Denmark, and Sweden, for example, have obesity rates only a third of the American rate, while Germany’s rate is only half as high… Walking and cycling also help alleviate traffic congestion, save energy, reduce air and noise pollution, conserve land, and produce various other environmental benefits.

What would that entail, and what would be the environmental benefits? A study commissioned by the Rails to Trails Conservancy clarifies these questions. It suggests that half of all the outings we take in a car are so close to home that we could bike there in 20 minutes. Twenty-five percent of our errands are significantly closer—accessible on foot in 20 minutes. Rails to Trails determined that “modest increases” in biking and walking by Americans “could lead to an annual reduction of 70 billion miles of automobile travel… equivalent to cutting oil dependence and greenhouse gas emissions from passenger vehicles by 3 percent.” Doesn’t sound like much? Here’s a little perspective. The U.S. Senate just worked for months to agree on a complex cap-and-trade scenario that might reduce GHGs by 20 percent (below 2005 levels) between now and 2020. Losing 3 percent by an immediate behavioral change looks pretty good by comparison.

The wobbly economy was a good prompt in that direction for some folks, a process that has been aided (in some places) by infrastructure. The City of New York has constructed approximately 200 miles of bike lanes and plans more. Bike traffic has already increased by 35 percent. And despite its harsh winters Minneapolis is ranked as one of the nation’s most bike-friendly cities (second only to Portland, Oregon), offering more than 120 miles of bike lanes and trails, bike-friendly commuter trains, and more. Even Los Angeles, one of the most sprawling cities in the nation, has invested in a detailed plan to encourage and accommodate biking among its population.

Many metro areas now have extensive bike and hike trail systems. This section of trail passes along the Minnesota River bluffs, west of Minneapolis.

Many metro areas now have extensive bike and hike trail systems. This section of trail passes along the Minnesota River bluffs, west of Minneapolis.

As in the 1930s, popularity has bred a host of new biking technologies. Among these is the electric bicycle. Although more expensive than traditional bicycles, e-bikes have a distinct advantage: a built-in motor. You pedal anyway, right? On an e-bike, some of the kinetic energy from that motion is converted to chemical energy and stored in a battery. It’s available when the going gets tough, such as when riding into a headwind or up a hill. So far, China and India represent the biggest markets for e-bikes. Of 23 million e-bikes sold in 2008, fewer than 200,000 were purchased in the U.S. An innovative new alternative is the Hauler. Built more like a recumbent bike, the Hauler’s larger frame offers space to carry passengers or cargo—up to 500 pounds. Its battery is charged by a combination of leg-power and the original source of energy: sunlight. A solar panel is mounted on the slanted “roof,” offering longer battery storage, faster speeds, and more oomph on long and challenging trips. The designers, Lorax Motor Works of Oregon, envision it as an ideal vehicle for any setting: local rides, long-distance trips, or in developing nations where the demand for vehicles is on the rise. And like all e-bikes, the Hauler achieves transportation with no emissions.

Whatever form it takes—from a rusty old Schwinn to the sleekest racer or the most advanced electric model—the bicycle is more than a toy, exercise machine, or vehicle. Albert Einstein claimed to have thought of the theory of relativity while cycling. Suffragist Susan B. Anthony saw the bicycle as a source of independence for women. And author H.G. Wells wrote, “When I see an adult on a bicycle, I do not despair for the future of the human race.” In 2008 U.K. Prime Minister Gordon Brown declared, “The place of cycling in our society is set to grow, and I am committed to doing everything possible to encourage that.” The statistics show that Americans also love biking. But are we willing to put on our helmets and ride as a solution to what plagues us?

SKYWATCH FRIDAY: Passing Thoughts

“Beauty has as many meanings as man has moods.
Beauty is the symbol of symbols.
Beauty reveals everything, because it expresses nothing.
When it shows us itself, it shows us the whole fiery-colored world.”
—Oscar Wilde


“Beauty has as many meanings as man has moods.

Beauty is the symbol of symbols.

Beauty reveals everything, because it expresses nothing.

When it shows us itself, it shows us the whole fiery-colored world.”

—Oscar Wilde

In the early morning hours I stand at the kitchen window, alone with the silence and my thoughts. The last few stars fade overhead as a pale glow touches the treeline across the lake.

To my surprise, a late-feeding bat appears over the meadow, making a wide sweep at canopy level. The bat passes just a few meters in front of the window. Suddenly it lurches to the side, down, then rapidly forward. Such maneuvers make bat flight appear haphazard and clumsy, but I know better. Bats are expert fliers, rivaling birds at every turn.

I think about the amazing structure of a bat’s wing. Evolutionarily, this wing and my arm are homologous—they have the same basic skeletal structure, which can be traced back to a common (if very distant) mammalian ancestor. In x-rays this homology would become immediately apparent. The main difference, of course, is that the little flier’s finger bones are proportionately much longer. A bird’s wing has fewer, more robust bones. This sturdy framework provides easy lift, even from the ground—but far less flexibility. Bats can not only bend the elbow but move each digit independently to make rapid changes in flight direction and speed. (What about the thumb, you may wonder? This shorter digit protrudes from the leading edge of each wing, serving as a grappling hook and all-purpose tool.)


This image, from a 1909 book by William Leche, depicts the homology of forearm structures among eight groups of vertebrate animals.

When hunting small prey, such as micromoths or mosquitoes, a bat may simply grab the insect in its mouth. Scientists at Wake Forest University have found that large prey, such as tiger moths, are handled differently. The bat zooms up to a large insect and sweeps it up in a wing. Then the insect is dropped into the cupped tail membrane. Finally the bat bends forward and gobbles up the prey, as if eating from a bowl. Keep in mind that all of this happens in milliseconds, while the bat is midair. Scoop—gulp—swoop! The red bat, one of our local species, shaves a step off this routine. It flies under the prey and executes a forward roll, making the capture directly into the tail membrane. So efficient.

As “my” bat flutters into the shadowy woods of our neighbor’s property, I idly hope its aerobatic foraging was successful. Moments later my attention is diverted to the bottom of the hill, where robins have begun to pour from the canopy of a big maple tree. They emerge in groups of two, six, then dozens at a time. Flying low over the meadow, their dark silhouettes cross those of Canada geese on the lake.

Now my meditative silence is officially broken. Robins chuck worriedly as they settle on the lawn for breakfast, and the geese wish each other good morning with a noisy chorus of whistles and honks. Another familiar morning sound comes from within my own home: the contact call of a Blond-Haired Boy.

There’s just a moment more to gaze out the window. Golden light reflects against low clouds and back onto the water. It’s a moment of simple beauty. I can’t pass this to anyone else. But I’ll carry it with me through the day.

Pull Over, Ma’am

Thankfully, those words—”Pull over, ma’am”—are not the reason I find myself on the shoulder of Interstate 35W at 7:00a.m. Nor is my action the result of car trouble. A different voice has caused me to stop the car on this Sunday morning-quiet stretch of highway. I have heard the call of beautiful scenery.

I resisted as long as I could. I’ve been driving through a pervasive layer of ghostly ground fog, which hovers like thin smoke over farm fields and wetlands. Streamers of water vapor dance slowly across lake surfaces. Thick white pockets pile up wherever the landscape forms a shallow basin. Now the sun has risen a few degrees above the horizon. Light is scattered through the layers of fog, filling the sky with peach-colored haze. I’m grateful for the lack of traffic so I can safely grab my camera from the back seat and shoot half a dozen frames.


Over the past week or more I have noticed the splotches of color touching maple trees in my neighborhood. Ground fog is the second clue I rely on to confirm that we are shifting from summer to autumn. This time of year the sun sets noticeably earlier and rises later. The days remain warmish, but in the prolonged hours of darkness Earth’s surface cools rapidly by radiation. As heat flows away from the land, air near the surface also begins to cool. When air temperature reaches the dew point, the particles of water vapor within it condense to form droplets of liquid water.

Yet only certain environmental and atmospheric conditions produce ground fog. Aside from radiative cooling, the critical factors are clear and windless skies. On cloudy nights, a larger percentage of outgoing longwave (infrared) radiation is held close to the surface. The air stays warm, so fog can’t form. A clear sky allows radiation to escape the atmosphere unimpeded. When breezes whip up, they push water droplets aloft to mix in the atmosphere. On still nights water droplets huddle into mini-clouds that remain close to earth. Ground fog usually evaporates as air warms in the hours after sunrise.

Back on the road, orange sunlight floods my car through the passenger window. On either side of the highway fingers of fog swirl upward, waking at the touch of the sun. A new day has begun. Autumn approaches.

On the Wing

(repost from August 29, 2009 on Intelligence with the Earth)

For weeks the yard has hummed (yes, that’s a pun) with ruby-throated hummingbirds. Throughout the day males, females, and juveniles zipped between feeders, flowers, perches, and hideouts. The chase was always on, and tiny birds whizzed past us, in pursuit or retreat, whenever we ventured into the yard. Actual fights between hummingbirds are apparently uncommon, though they seem to expend endless energy keeping each other from nectar sources.

In Birds of America, John James Audubon described this habit. “They are quarrelsome,” he wrote, “and have frequent battles in the air, especially the male birds. Should one be feeding on a flower, and another approach it, they are both immediately seen to rise in the air, twittering and twirling in a spiral manner until out of sight.”

A few years back I read an article about hummingbirds in Smithsonianmagazine. The author commented how fortunate it is that hummingbirds are not as large as crows. That image has remained in my mind. The ruby-throated hummingbird’s bill accounts for one-fifth of its body length. Expand the hummer to crow-size and its bill would be more than 10 centimeters long. The pileated woodpecker provides a useful model. This bird is of comparable size to the American crow, but its bill is elongated like Pinocchio’s nose after he’s told a series of whoppers. Rather than being chisel-shaped like the woodpecker’s, however, a hummingbird’s bill is rapier-thin and sharp. Our Superhummer would be a Musketeer among birds. Mon dieu!

Pileated WoodpeckerThe total length of this adult male pileated woodpecker may be close to half a meter. Imagine a hummingbird with those proportions!

The dogfights haven’t ended among our remaining hummingbirds, but a sudden decline in population density has reduced the intensity of these interactions. Three days ago I noticed the absence of any males in the yard. Male ruby-throated hummingbirds always leave in August, heading gradually toward the Gulf Coast. Females and juveniles remain somewhat longer, into October if conditions permit. During that time they may share the yard with dark-eyed juncos and pine siskins. These songbirds also travel south after nesting, but because they eat seed (among other reasons) their migration from Canada may end right here in central Minnesota.

I have often wondered whether the same birds somehow return year after year to our yard. Site fidelity is an aspect of migration that is of concern to biologists. But it can be difficult to prove. Banding studies  shed some light on the question for ornithologists. Captured birds are fitted with tiny metal leg bands. Each band is stamped with a unique number, and may also carry a discrete color pattern. Bands allow individual birds to be identified upon sighting or recapture. At Hilton Pond Center in York, South Carolina, biologists banded 3,614 ruby-throated hummingbirds between 1984 and 2007. More than 430 of these birds came back to Hilton Pond the spring after banding. A couple returned several years in a row. Amazing information can be obtained from such simple techniques, but they require funding, staff, and infinite patience.

Hummingbird resting on raingaugeAudubon wasn’t terribly scientific when he described the ruby-throated hummingbird as a “glittering fragment of the rainbow”—but he was utterly accurate. I watch a little female perch atop our rain gauge between bouts of feeding and chasing. Her belly is rotund with nectar and she looks perfectly fit. This wee gem has a long journey ahead. I don’t know if she’ll make it back to this yard in the spring. But we’ll keep the nectar flowing, just in case.

Afternoon Delight

(repost from August 22, 2009 on Intelligence with the Earth)

Rain or shine, subzero or sweltering, around 2:00 p.m. each weekday some internal alarm prompts me from my chair toward the kitchen. Although this is a short migration, it involves a radical shift in habitat. My office is tucked on the north side of the house and flanked by an Entish pin oak tree. Those with an aversion to low light might find the room too solemn, but I enjoy its cool, shady attitude. It feels as though I have my own little bower among the branches of the house. I work here for hours at a stretch, cocooned in a silence that is conducive to concentration but not oppressive. There’s a palpable shift in my awareness when I enter the kitchen, which is flooded with light throughout the day and in all seasons. Wide windows on its east and west walls, and exposure from the south through an adjoining mudroom, make the kitchen open and lively. This is the real heart of our home. Even a quick infusion of its light, color, and space gives me just the dose of energy I need to remain focused through the afternoon. A cup of tea doesn’t hurt, either.

Teatime is not a fancy affair. I don’t prepare food, and never even sit down. But there is a ritual associated with this break. I take down two mugs from the cabinet. One is chosen randomly, though it can’t be too large. The other is my favorite mug, made of thick, cream-colored ceramic with a handle that looks like a twisted twig. Across its surface are painted two of the birds that commonly appear in our yard: the Baltimore oriole and the blue jay. The style of painting looks somehow old-fashioned, like it belongs in a dusty field guide you might find tucked away in your grandparents’ library. I choose a bag of good black tea to go in the first mug. Something fruity or spicy goes in mine—but no caffeine allowed. Finally I fill the burnished metal teakettle and place it on the burner. Now begins my favorite part of the routine. Until the kettle sings I have a few free moments, with nothing more important to do than watch.

Much as I love spending time outside, it’s no exaggeration to say that I could gaze out the kitchen windows for a whole day. The east window provides a view of the hillside meadow and lake that comprise our “backyard.” We don’t live in isolation; I can see houses on the far lakeshore and, at night, lights from the highway beyond. Yet this is something more than the typical sprawling suburban property. It’s just on the edge of wild. We routinely observe loons on the lake and bald eagles overhead. The tame and familiar wildlife—deer, raccoons, and woodchucks—are occasionally joined by minks, coyotes, and huge flocks of turkeys.

Front Yard The expansive lakeview is always tempting, yet today I’m drawn to the smaller, paired windows over the kitchen sink. There’s no grand vista framed here—just the front yard. It’s a yard like many others in our area. There’s a deck and a small, screened cabin where we sometimes take our meals. Several flower patches and bird feeders are scattered across the open space. A big, hundred-year-old boxelder tree throws shade over the grass where my young son plays. A tidy orchard gives fruit of three varieties, and a white picket fence defines part of the property line. This view is appealing not so much for its scale as for its intimacy and the relatively invisibility offered by a reflective window pane. Wildlife—particularly birds—come so close to the windows that it’s breathtaking. At this moment a downy woodpecker clings to a suet feeder half a meter from my face, but the bird is heedless of my presence.  Downy Woodpecker on suet feeder

The woodpecker circumambulates the birchbark feeder in search of a good toehold. I lean over the sink to carefully open the opposite window. Moments later a distinctive sound reaches my ears. It’s the low, whirring drone made as a hummingbird’s wings beat the air more than 50 times per second. A male ruby-throated hummingbird rockets in from the east side of the house. It clears the suet feeder—and my corner window—by a narrow margin of safety. The emerald green bird’s destination is the nectar feeder that hangs from a pole in the deckside flower garden. It hovers before the feeder, dipping down to feed then popping back nervously to look around. Suddenly the hummingbird pivots toward me. The feathers of its gorget (throat)—which had at first appeared black—now flame metallic red. This burst of iridescence occurs when sunlight reflects off microscopic air bubbles located inside each barb of the gorget feathers. (If you’ve never examined a feather closely, there is a long, stiff central shaft with many thin “branches” extending off the sides. These branches are the barbs.) Iridescence is only visible when the bird and observer are face-to-face. The flash of color fades when either party changes angle relative to the sun. And it doesn’t take long for this to happen. The hummingbird holds its position barely long enough for me to complete a full breath cycle. It emits a rapid series of high-pitched chitters that seem out of proportion to its size then lunges forward in a wide, arcing sweep over the deck. I suspect the source of the bird’s annoyance, but it takes a moment for me to locate it. Another male hummer has flown near the feeder.

Hovering male hummerMinnesota lies too far north to support hummingbirds year-round. Their presence is limited to the warmer months, when flowers are blooming and nectar supplies are ample. Even when food is readily available hummingbirds must conserve energy by entering a hibernation-like state called torpor for part of every day. A generalist feeding strategy also aids their survival. Rather than focusing on a narrow category of foods, they feed opportunistically on a variety of items. All hummers are known for their love of nectar, but ruby-throated hummingbirds are especially open-minded tipplers. Due to loss of habitat throughout their range, human-made nectar feeders are a crucial source of food. Where they can get it, however, these birds take nectar from any reddish, bell-shaped flowers large enough to accept their beaks. That includes everything from phlox and Monarda (aka beebalm and wild bergamot) to morning-glory and honeysuckle. In our yard, ruby-throated hummingbirds also go for giant hyssop. The pale lavender flowers of this mint species are tiny, but they form tall inflorescences atop stems that tower over my head. Ruby-throated hummingbirds are known to follow sapsuckers in spring. The sapsuckers drill small, round wells in the bark of maple trees to release sap, and hummingbirds take advantage of the free resource. Throughout the year they also seek small insects and spiders, capturing prey mid-flight or scooping it off surfaces.

Hummingbirds spend at most four months in Minnesota. They show up during the second or third week of May, depending on weather conditions here and along their migratory path from the south. I always try to have the nectar feeders out and waiting, for they a. It seems that a creature so slight must be tossed by the wind like cottonwood fluff. Hummingbirds appear to have turned this liability to an advantage in some circumstances. When possible they wait to fly with favorable tail winds, allowing the gusts to provide a push in the right direction during migration.

Juvenile male hummerTheir imperative here in the northlands is clear: establish a territory, build a nest, and raise a healthy brood of Lilliputian offspring. By early August the breeding season has ended and the birds begin to respond to different internal rhythms. Migrants from breeding populations in Canada and northern Minnesota now join our resident hummers. If mid-August seems a bit premature for migration, consider that by mid-October these wee creatures must cross the Gulf of Mexico to reach their winter ranges in the Yucatán Peninsula and Central America. The birds seem to focus on one goal in preparation for this long journey: getting fat. During the breeding season male ruby-throated hummingbirds have an average mass of 2.5 grams. Balance an American penny on the tip of your finger to get a sense of how insubstantial that mass is. Females can be up to 2 grams heavier—closer to the mass of a nickel. In less the two weeks, through a vigorous program of nectar sipping, a hummer may increase its body weight by 75 percent. No body builder ever took weight gain more seriously. At this time the birds engage in fast and furious territorial battles over access to feeders and flower patches. Females are as just as contentious as males. The bird I’m watching now probably nested in our yard, and is not eager to share resources at such a crucial time. I crane my neck to watch as he chases the interloper away, but the two miniscule green birds are immediately lost among the foliage.

Distracted by the hummingbird drama, I’m startled when the teakettle begins to sing. I pour the water and leave the cups to steep for the requisite three minutes. Delivery of my partner’s steaming tea is the last part of this afternoon ritual. It’s sometimes an excuse for conversation, but more often a simple gesture, a quick and quiet interlude in the midst of our mutual workdays. When I get back to the kitchen my herbal tea will require only a spoonful of honey to make it ready. Allowing myself a last glance out the window, I see that a mean, green flying machine is back at the nectar feeder. Whichever of the two male hummingbirds has prevailed, it wastes no time in savoring the sweetness of its prize. As I return to my quiet work habitat, that sweetness lingers in my mouth as well.

What’s the Buzz in the Garden?

(repost from July 22, 2009 on Intelligence with the Earth)

It’s not for naught that the Monarda plant is also called beebalm. I spent half an hour on Monday morning photographing massive and beautiful bumblebees as they tottered and swayed in flight between scarlet-flowered plants in our upper garden. Although my huge black lens and I often came within 6 inches, the bees were too consumed with sipping nectar to take any notice. Must have been a good vintage!

The bees may have been tipsy, but they were highly efficient. How can I be sure? Today the Monarda patch looks scraggly and sad. Each inflorescence is almost bald, with only a few withered and fading flowers forming a crown around the perimeter. But it’s all good. When flowers fall away it’s a clear indication that the hard-working dumbledores (that’s Old English for bumblebee) did their work of pollination. The plant can now direct its energy toward making seeds.

Bumblebee on Monarda inflorescenceThe bee shown here is a queen of the species Bombus auricomus. It’s one of the largest bumblebees in Minnesota. Bombus means “boom,” referring to the bee’s loud vocalization (as compared to the murmuring buzz made by bumblers of other genera.) Auricomus is from the Latin, and translates as “with golden hair”—probably describing the distinctively wide swath of yellow hair covering the central tergites. (Tergites are armor-like segments of exoskeleton that form parallel rows down the bee’s abdomen. Females have 6, males 7. Good luck counting them!) For some reason, scientists have never bothered to give this bee a common name. So we’ll call her the golden-haired booming bee. A proud name for a lovely creature.

Faded MonardaBumblebees are not the exclusive pollinators on Monarda—hummingbirds love it, as do larger butterflies. It’s easy to see when the pollinators have done their work well.

Bumblebee on Liatris

For comparison, this is the much smaller Bombus bimaculatum—the two-spotted bumblebee. It’s pollinating my prairie blazing star (Liatris). I hope you can see the shining flecks of orange-gold pollen scattered across the bee’s lower abdomen.

« Older entries