The Fall Migration of Raptors

By Emily Brodsky

Just about when the leaf peepers begin flocking to the roadways to observe Vermont’s spectacular autumn foliage, an equally-enthusiastic set of nature lovers is trekking up the peaks to watch a different seasonal event: the fall migration of raptors.  Also known as “birds of prey,” this majestic group includes the eagles, falcons, hawks, vultures, ospreys, and the less-familiar but no-less-impressive group called the harriers, of which North America has only one (the beautiful Northern Harrier).   Perched on a mountain outcropping, one can predictably see large numbers of these birds as they make their way to southern climes.

Whether you’re a veteran bird-watcher or a novice, raptor-watching (usually referred to as “hawk-watching,” even though other types of raptors are included) is a great way to spend an autumn afternoon.  One of its draws is that the birds are highly visible.  Unlike the diminutive songbirds, which hop around incessantly and hide in dense shrubs, raptors are large, steady, and during migration, exposed.  Also, because each group of raptors flies differently and has a distinctive shape, these birds are easy to tell apart.  The peregrine falcon, for example, has long, pointed wings, which it flaps continuously for its fast, powered flight.  In contrast, the bald eagle rarely flaps and its broad, sturdy wings make it look like a flying plank.  At the popular hawk-watching sites, you’re likely to find fellow observers on the summit to help you with identification; learn the shapes and flight patterns of the major groups and you’ll be a hawk-watching maven in no time.

 

So when and where is a Vermonter to begin?  The peak of fall raptor migration is from mid-September to early November; try going at different times of the season to see different species.   The most popular hawk-watching sites in Vermont are Mount Philo, 15 miles south of Burlington, and Putney Mountain in the southeast corner of the state.  Snake Mountain in Addison and Mount Ascutney in Windsor are also decent spots, as are Coon Mountain, just beyond the ferry terminal in Essex, New York, and Mount Tom in Massachusetts, straight down the Connecticut River from Brattleboro.

In addition to being a popular place for recreational hawk-watching, Putney Mountain is also an official migration monitoring site.  Because raptor migration is predictable and easy to watch, people have been counting migrating raptors and recording their numbers since 1934, when the first official count site was established at Hawk Mountain Sanctuary in Pennsylvania.  Since then, numerous similar counts have been established all over the globe, from the Panama Canal to the Strait of Gibraltar.  The long-term migration data collected at these sites allow scientists to monitor raptor populations; numbers vary greatly from year to year, but over long periods of time, scientists can identify trends.  The decline in juvenile Bald Eagles migrating past Hawk Mountain Sanctuary in the 1970s alerted Rachel Carson to the threat of DDT to these important predators, and she wrote about this trend in Silent Spring, the influential book which led to the ban of that harmful pesticide.  Visit the Putney Mountain Hawk Watch just for fun, or participate in the count to play a role in history.

You may be wondering why people hike up mountains to watch raptors migrate, instead of just observing from their driveways.  Do mountains simply afford better views of the sky?  The answer is that raptors concentrate along specific routes during the fall migration, and just as you’re more likely to find lots of cars on I-89 than on a dirt road in the sticks, you’re much more likely to see large numbers of raptors along these migration flyways.  Flyways tend to stick to mountain chains, because these topographic features allow for easy flight.

Source: http://donsnotes.com/nyc-nj/hawk-watch.html

As you can probably imagine, migration is exhausting.  When we humans are exhausted, we can take a nap and recharge; to a raptor, exhaustion usually means death.  Some raptors, such as Broad-winged Hawks, fly as many as 4,500 miles in about nine weeks to reach their wintering grounds.  To make it that far, they must do whatever they can to save energy along the way.  Lucky for raptors, there are some great energy-saving tricks.

When winds blow against a barrier such as a mountain, they’re forced upwards.  During migration, raptors fly along the sides of mountain ridges to take advantage of this upward push of air, called an updraft.  Instead of flapping their wings to generate lift, raptors can simply spread their wings wide and ride the updrafts like a surfer rides a wave.  Updrafts can carry raptors hundreds of miles along a continuous mountain chain like the Appalachians, which conveniently runs from north to south.  Not only does this strategy save migrating raptors an enormous amount of energy; it also makes for a great show, since updrafts carry the birds right past the slopes.

Source: http://www.loudounwildlife.org/HHHawksInAir.htm

Updrafts are helpful when the wind blows.  Early in the fall, however, when the sun is still high and the air is calm, raptors rely more heavily on another phenomenon of physics. You’ve probably seen hawks or vultures flying in circles, high in the sky with their wings outstretched.  These birds are using a trick called soaring flight.  As you know, the surface of the Earth is quite variable; some spots are covered with rocks, some with woodlands, and some with houses and streets.  When solar radiation hits these surfaces, they each heat up at a different rate, and thus, the air just above the ground heats up unevenly.  In spots where the ground is warm, the air rises, forming columns called thermal air currents (or thermals, for short).  Raptors find these thermals, and spiral upward without having to flap their wings.  When they get nice and high in one thermal, they exit and glide toward another (losing altitude but gaining distance), and they rise up again.  In this way, they can travel long distances without expending much energy.  Mountain slopes heat up faster than the valleys below them, which means they’re good places for thermals; thus, raptors stick to the mountains even on calm days.

Mountains aren’t the only places in which to spot large numbers of migrating raptors; these birds tend to follow shorelines as well.  Thermals don’t form above water bodies like they do over land, because water releases heat slowly and evenly.  Without thermals or updrafts, raptors must use flapping flight – the most costly kind of flight.  For migrating raptors, flapping across a large expanse of water is risky business: if they run out of energy, they drown.  Consequently, most raptors avoid flying over large water bodies, and when they reach one along a flyway, they hug the coast – or, if they must cross, they find the shortest crossing.  Short crossings and narrow strips of land between water bodies act as concentration points, or bottlenecks, funneling thousands of raptors over the land as they avoid the surrounding water.  Examples are the south-facing peninsula of Cape May, New Jersey, the narrow crossing from Europe to Africa across the Strait of Gibraltar, and the thin strip of coastal plain at Veracruz, Mexico.

Migration behavior varies among species.  Broad-winged hawks, for example, depart for their approximately 4,500 mile trek to northern South America in early September when the thermals are strong.  Aptly named, Broad-winged Hawks are built for soaring flight.  Although Broad-winged Hawks are solitary for most of the year, they flock during migration.  Scientists believe flocking helps the birds to find the best thermals, although it could serve other purposes as well, such as protection; even most raptors have to worry about predators.  Broad-winged Hawks are one of the main attractions at raptor watch sites, since it’s possible to see hundreds or even thousands of them soaring together.

Unlike Broad-winged Hawks, Cooper’s Hawks are mediocre long-distance flyers.  These birds have stubby wings and long, rudder-like tails; they’re built for maneuvering among the branches in their forested habitats.  Cooper’s Hawks don’t generally migrate very far, and some don’t migrate at all.  Those individuals that do migrate tend to do so later in the season than Broad-winged Hawks, departing in October and November, and dropping off along the way as they find suitable wintering grounds.  They rely heavily on updrafts to save energy during the trip, and are easy to spot on north-facing ridges.

You may ask: why do the birds go to all this trouble, anyway?  Or, better yet: if they don’t like the cold, why don’t they just stay in the south, where the weather is toasty-warm year-round?  A common misconception about migration is that it’s prompted by temperature change.  Since we like to follow the warmth of the sun in the wintertime and many of us head south to Florida beaches, we assume birds and other migratory animals share our preferences.  In most cases, however, migration relates to temperature only indirectly.  In actuality, migration is mostly about food.

As the northern days grow shorter and the temperatures drop, plants cease to produce fruits.  Annual plants reach the ends of their lives, while perennials drop their leaves and transfer their sugars into stems and roots for winter storage.  Many of the insects and mammals that feed upon these plants turn in for a months-long slumber, or stock their larders with seeds, nuts, and other high-energy morsels and settle into their winter dwellings.  Ice creeps over the surfaces of lakes and ponds, sealing in their inhabitants until the spring thaw.  Carnivorous birds suddenly find themselves with little to eat.  So, they follow the food.  And, because it coincides with warmer weather, the food just so happens to be in the south.

When migratory raptors reach their wintering grounds, they must compete with resident birds for food and roosting sites.  This works out okay in the winter, when the birds need only worry about themselves; once spring comes along, however, the birds must compete for nest sites, and food for their offspring as well as for themselves.  Making the grueling return journey is worthwhile, since the raptors will have their choice of nesting spots when they reach their mostly vacant northern homes.  They’ll also get there just in time for dinner; after the snow and ice melt, there will be fish, rodents, songbirds, and juicy insects around just about every corner.

 

 

 

Jack-in-the-pulpit: The Forest Floor’s Hermaphrodite

By Leah Mital-Skiff

I don’t want to make any controversial statements about whether it is easier to be male or female, but it is tempting in this case. When times are good on the forest floor, Jack turns into Jackie and when the going gets rough, Jackie turns back into Jack.  We could say that Jackie likes to cruise during the good times, but her reproductive work requires a more nutrient-rich environment.

Jack-in-the-pulpit, Arisaema triphyllum, is hermaphroditic and begins adulthood as Jack, its male expression.  After maturing past the seedling stage, the plant will produce male flowers on the spadix, the cylindrical reproductive structure commonly referred to as “Jack” and are buried deep inside the pulpit, covered by the hooded spathe.  The musty-smelling spadix attracts gnats that enter through an opening in the base of the spathe and move up and down the spadix gathering pollen from the male flowers.

If conditions were ideal the previous year, elsewhere in the forest, another jack-in-the-pulpit stored enough energy to emerge this year as a female, producing female flowers.  This growth takes a significant amount of energy and requires optimal conditions of light, nutrient availability and moisture.  Thus, Jack will only emerge the next year as Jackie if the conditions are favorable.  Jackie comes endowed with two sets of leaves in order to capture more sunlight and produce the energy she needs for reproduction.  Male plants in a stressed environment will remain in the male form into the next year.  Females under stress will revert to male and conserve energy.

Jack-in-the-pulpit is conspicuous in the early fall. The brilliant red fruits draw the eye from the changing canopy foliage in late September to the floor of eastern mixed hardwood forests.  The bright red show on an autumn day denotes its success after many potential cycles between its male and female expressions to result in the production of fruits.

Perhaps the Jacks boast that they can tough out a nutrient-poor environment and wait out the bad times. Jackie then reminds us how much more energy is needed for her role in reproduction; males have the easy job of producing pollen-bearing flowers.  In the end, the strategy of sequential hermaphrodism ensures more successful reproduction.  In a stressed environment, the jack-in-the-pulpits in the area simply do not produce seeds.  They conserve their resources and produce fewer seeds of a higher quality and viability for germination.  When we see the brilliant red among the browning leaves of the fall, the story ends in success of gender synchronicity. The male plants have browned and wilted along with the other plants of the forest floor while Jackie boasts hermaphroditic success in a show of red to beckon the birds to disperse her seeds. Jackie does steal the show in the end.

 

 

Doll’s Eyes

by Sophie Mazowita

A dozen eyeballs, dangling from their sockets, stared up at me on my last walk through the woods.  I was strolling through the forest on a gloomy Sunday afternoon, seeking out plants for a botany project, when I came across the startling sight.  The small eyes stood out from ten yards away, stretched out on their swollen red arteries.  A small black pupil marked the middle of each white, its stare drawing me in.

A few steps closer and I recognized my “observer” as a common yet ever-creepy resident of our woodlands: the 2-foot tall White baneberry (Actaea pachypoda).  The plant is a member of the buttercup family, but it bears little resemblance to its golden-flowered relatives.  It’s most aptly known as Doll’s eyes, and true to this moniker, each of its white berries looks like it has been plucked straight out of the head of a porcelain doll.  Up to 30 of the fruits sit affixed to a stalk that towers over the plant’s leaves and turns a bright red as the summer progresses.  The black “pupils” are actually the vestiges of some flower parts from earlier in the season.

The plants are poisonous to humans (though I doubt any would be tempted), but they offer food to birds.  Imagine the sight of a bird pulling an “eye” from its thick red stalk and swallowing it whole!  A visit to a hardwood or mixed forest will offer your best chance at viewing this spectacle; the baneberry plants grow in the shade below mature maple, basswood, and other broadleaf trees.  The white berries should stand out above a dozen or more jagged-edged green leaflets that strech out horizontally, about a foot off the ground.

Doll’s eyes is but one of the attractions of early autumn woodlands.  Most people would pick the spring as the prime time to view wildflowers; when trees are still bare, spring ephemerals like trilliums and trout lily put on a show on the sun-soaked forest floor.  The end of the growing season, however, offers a whole other set of treasures.  White baneberry’s eyes follow you through the woods until the frost hits.  Jewelweed seed pods offer an explosive surprise to anyone who brushes past.  Beech branches thick with fruit begin to drop their bounty, a favourite of black bears.  A leisurely walk and discerning eye will offer many rewards.

What’s your latest discovery?

Why do birds fly south for winter?

by Doug Morin

I opened my backdoor and stepped into the yard to a flash of red and buzz of wings – a hummingbird.  Maybe the last of his kind I will see this year, he perched on a small branch, tilted his head to either side, then flew off down the road.

Here in Vermont, hummingbirds disappear in late September and reappear in late April.  We know the story well: birds fly south for winter.  Of course they do.  But, have you ever wondered why?

First, let’s turn the clock back a few thousand years.  It turns out, most migratory birds in North America trace back to ancestors that lived in the tropics.  Over time, these birds expanded their ranges until a small proportion eventually made it to North America.  Even today, most birds arrive in late spring and leave in early fall – spending less than half their year in North America.  The real question then isn’t, why do birds fly south for winter? but, why do birds fly north for the summer?

This is a particularly important question because migration carries a deep cost.  It’s easy to discount the effort required to fly to and from the tropics, given the convenience of modern air travel (though I’d still like more leg room), but the journey for a bird takes huge amounts of time and energy as well as exposing the bird to unfamiliar environments and predators.  The hummingbird in my yard, for instance, weighed only as much as small handful of paperclips, yet over the next weeks, it will first fly to the southern coast of the U.S., then across the Gulf of Mexico to the Yucatan Peninsula in a single, non-stop flight lasting nearly 24 hours, and finally overland to southern Central America.

The time, energy, and risk involved in migration have severe impacts: migratory birds are twice as likely to die in any given year, compared to tropical non-migratory birds.  So, why in the world do they do it?

The answer is that the benefits outweigh even these high costs.  Since relatively few birds come to North America, migrants have easy access to abundant insects, plants, and nesting grounds.  With plentiful food and territory, migratory birds produce many more offspring each summer than their non-migratory counterparts.  As winter arrives, however, insects and plants disappear, and the diminished food supplies (rather than dropping temperatures per se) drive migrants south.

Overall, migratory birds do not live as long as non-migratory tropical birds, but produce more offspring each year – resulting in nearly the same number of over their lives.  Since the number of offspring determines how many birds will be in the next generation, these two strategies are roughly equivalent in evolutionary success.

So, the birds that grace our summers with color and song do so for windfall payoffs, but at immense cost.  As you see the last of our migratory birds leaving over the next few weeks, wish them well on their way.

Also, look out for a more in-depth post by Emily Brodsky on Raptor Migration in the next few days!

 

Note: For excellent maps of where birds spend their summers and winters, see the Cornell Lab of Ornithology’s website All About Birds.

Chicken of the Woods

by Becky Cushing

Frog legs, rabbit, octopus, sea lamprey: Tastes just like chicken. But a mushroom? That might take some convincing.

Purple toadstools dot moist ground. Tiny aliens emerge from rotting wood. A stalk shoots from leaf litter on the forest floor. Like Alice’s Wonderland, the damp woods in and around Burlington are splattered with wild mushrooms. While identification of the 70,000+ worldly fungi species (many more unnamed) might seem like a daunting task, learning one or two of the “showy” local varieties can be a good way to get started.

Two weeks ago I was exploring Centennial Woods, a natural area managed by the University of Vermont, when I caught a flash of bright orange through the tall white pine and maple tree trunks. Like a reflective safety vest, it stood out against the earthtone browns and greens of the surrounding woods. Squinting harder I could make out suspended shelves attached to one side of the rotting trunk. Getting closer I clearly saw half a dozen two-toned fanned layers, a giant-sized carnation corsage.

Becky with her find.

Becky with her find.

Crouching down I realized this mass was more than a foot wide and each 3-6 inch orange shelf layer was outlined along the waving free edge by a pale yellow, like fresh cow’s milk. Subtle web-like strands of white mycelia penetrated cracks in the dead trunk where, hidden from view, they obtained nutrients through decomposition. If this tree had been alive, it most certainly would have minded this organism’s parasitic affinity for heartwood. As it were, the dead trunk suited the mushroom’s role as a saprophyte, or decomposer.

I recognized this rubbery fungus. I had seen it before. Some call it “sulphur shelf” or “chicken mushroom.” Wikipedia even suggests “quesadilla of the woods” — a bit of a stretch if you ask me. It was Laetiporus sulphureus or “chicken of the woods.”

I’m not a mushroom expert. In fact, I first learned about “chicken of the woods” at an informal dinner party: I thought I was eating chicken. And yes, with loads of butter, it tasted much like the popular poultry. Luckily the skilled chef had several decades of mushroom foraging under his belt but it leads me to an important point: Never ever eat a mushroom without an extremely confident identification (which is usually preceded by many years of foraging experience). For others, past mistakes have caused disintegrated livers or failed kidneys. With 70,000 to 1 odds? It’s just not a good idea.

Subtle Wonders of the High Sierra

by Cathy Bell

After a night spent deeply burrowed into the warmth of my down sleeping bag, I wake to discover that my tent has abruptly transformed itself from a cozy refuge to a swelteringly confined space.  The sun has only just cleared the ridgeline of Cirque Peak, but its rays are strong here at 11,000 feet above sea level, and my little tent heats up like a greenhouse.

Changing from long underwear to field clothes, I clamber out of my tent to find a heavy frost riming the sedges along Siberian Pass Creek.  It is the morning of July 20th.  I don’t have a thermometer, but last night didn’t feel too cold.  I’d guess that the overnight low was in the high 20s.  I stretch and take my time over breakfast, giving the sun a little more time to warm the high country before I set out for my day’s fieldwork.

foxtail forest and Siberian Outpost, Sequoia National Park

Looking over Siberian Outpost.

I’ve set up camp at the edge of a foxtail forest, where widely-spaced pines yield to the treeless gravel flats of the fetchingly-named Siberian Outpost.  Around me, steep talus slopes rear skyward, hinting at the expansive alpine plateaus above.  I am spending my summer in the wilderness of Sequoia National Park, just ten miles south-southwest of Mt. Whitney in the southern Sierra Nevada.  At 14,494 feet, Whitney is the highest peak in the lower 48, but—though it soars a gasping 3,000 feet above treeline—the famed summit is just one of a dozen exceeding 14,000 feet in this region.  Spectacular alpine country abounds: I’ve heard that the Sierra Nevada feature more acres above treeline than any other mountain range in the conterminous 48 states.

The rocky, seemingly-barren high reaches are the reason that I find myself here, in some of the wildest country remaining in the United States.  Though the Sierra peaks seem lifeless from a distance, a closer look reveals a surprising diversity of hardy alpine plants growing amongst the boulders.  I love this hidden world.

tiny Ivesia grows in a rock crevice

Tiny Ivesia grows in a rock crevice.

At the same time, I fear what the future holds.  Research suggests that alpine vegetation is especially at risk from the rapid shifts in temperature and precipitation caused by anthropogenic climate change.  Unfortunately, there are big gaps in our understanding of how high-elevation vegetation will respond to a changing climate.  In fact, since alpine areas are such hard places to access, we don’t even know if their plant communities have already started showing the effects of a warming world.

To try to fill in some of those holes, my master’s project work involves searching for vegetation survey plots that were established some twenty-five years ago.  When I can find the plots, I re-survey them in an effort to compare the plant populations we see today to the ones that were documented in the 1980s, hoping to determine if alpine species are already showing a response to climate change.  So far, the project is going far better than I had dared to hope; I have found every single plot I’ve sought.  Today, I’m going after Plot 403.  I tried to visit it ten days ago, on July 10th, but it was still buried beneath two feet of snow.  I’m hoping I have better luck today.

Shouldering my frame pack with its twenty pounds of field gear, I hike upvalley for half an hour, then scramble up a bouldered slope to the top of a ridge.  As I walk, the rhythm of my footsteps and breath ease me into an almost meditative state.  I take in the dramatic views and reflect on how the wilderness of Sequoia National Park is beautiful but vulnerable.  Though we think of national parks as pristine, even our most highly-protected places are not insulated from human impacts.  The beautiful and diverse plant populations of the High Sierra could be pushed out by changing conditions or the arrival of other plant species, irrevocably altering the character of this unique and inspiring wilderness.  In order to preserve and protect this place for future generations to enjoy, we first have to determine if and how it is changing—and that is what my project is all about.

The ridge brings me west onto the rocky fellfields of the Boreal Plateau, where I start looking for the steel stake that marks the center of Plot 403.  An expansive snowfield still clings to the slope to my right, but it lies east of where the plot should be, and I think I’ll be able to find the plot marker.  I methodically work back and forth, trying to line up the mountains in the distance with rocks on the ground until they match the relocation photo on the clipboard I clutch in my left hand.

dead alpine plant with massive taproot

In life, this plant grew only about an inch above the surface of the ground, but its massive taproot kept it anchored among the rocks.

A brown tangle on the ground catches my eye.  Distracted for a moment from my search, I stop and kneel to peer at the crushed and matted-down plants that the rapidly receding snow has revealed.  Though seemingly dead, most will soon pull energy from their deep taproots and green up, life reasserting itself after the long winter.

Long winters define this world above treeline.   A plant trying to survive here must contend with a growing season of only about two months, howling winds, and an environment that—despite abundant snowfall—is startlingly short on liquid water during the summer, when growing plants require it.  It’s a tough place to make a living, but the alpine plants of the Sierra Nevada are well-adapted to their environment.  They have weathered gradual shifts in climate for a long time.  They are survivors, I know.  I just hope they are able to cope with the climate curveball we have thrown them.

Straightening up, I resume my search for Plot 403, and in just a few minutes I glimpse a flash of reflected sunlight off the center stake.  I take off my pack and get to work.

A Bypassed Giant

by Rachel Garwin

What’s the last amazing thing you overlooked?  I discovered mine last Wednesday in Centennial Woods, a 65-acre natural area near the University of Vermont campus.  A friend and expert naturalist was

white oak sketch

White oak sketch.

sharing his local knowledge with a group of undergrads, and I had tagged along.  The familiar path turned to the left in front of me, but I looked at the woods beyond it as if for the first time.  Gore-Tex dripping with unseasonably chilly rain, I stared unbelieving at the biggest white oak I’ve seen in Vermont.  A white oak I’d never noticed before, despite passing it scores of times in the last year.

Its whitish, ridged bark transfixed me, and I longed for the warmer conditions favored by this southern species.  I heard my friend estimate its age around 300 years, but how could that possibly be?  Too soon we walked away; commitments required our presence back on campus.

For the rest of the week, the white oak filled my thoughts.  My wonder pulled me back to the woods on the crisp, clear Saturday that followed.  I marveled at the oak itself, but also looked at the forest around me with new eyes.  Had I been asked to describe the patch a week before, I would have shared my general impressions of Centennial Woods: a weedy jumble of pioneer trees—red maples, paper birch, white pine—and invasive shrubs that grew up after field abandonment at least sixty years ago.  Now I wasn’t so sure.

White oak acorn caps, © 2011 Rachel Garwin

White oak acorn caps.

Instead of that theoretical assemblage, hardwoods covered the hillside above me. Red maples’ old, platy bark and smooth, young trunks textured the forest, spotted here and there with gargantuan, grooved-barked white pines.  The occasional pines shot straight into the canopy, towering above the broadleaves glinting yellow-green in the sun.  Instead of poison ivy—a scourge on the rest of Centennial Woods—intermediate wood fern and sensitive fern carpeted the duff-covered ground.  Sun flecks danced across fern and leaf alike; their shimmers added another lively layer atop the chatter of insects, blue jays, and red squirrels.

flaky oak bark, © 2011 Rachel Garwin

Up close, the rough, ridged bark is surprisingly flaky.

Cool air washed over me.  I thought of the jacket hanging on the newel post at home, but resisted the impulse to run after it.  Instead, I hopped off the fallen pine and wrapped my arms around the oak, fully two wingspans around.  Rough, flaky bark pressed into my cheek as I looked up along the trunk.

The spreading crown of layered branches dominates the sky.  The branching pattern differs between the lower and upper trunk: until the tree rises above the neighboring red maples and rotting white pines, branches grow only on the southeast side of the oak.  Once free of competing limbs and leaves from other trees, however, the branches radiate in 360 degrees.  Since branches in high light environments have more access to abundant energy, they grow more quickly—and are more likely to survive—than branches in shady environments.  Once the oak’s top emerges from beneath the canopy, however, its branches have equal energy opportunities and reach in any direction.  It follows, then, that this tree grew up on the edge of shady woodland to the west and north, much like the present patch of woods is situated today.

I walked around the massive trunk, careful of roots and uneven ground.  The barbed wire took me by surprise.  Extending from the very center of the tree, the rusted, twisted strands extended east-northeast.  I imagined the wire extending into a fence running further northeast and southwest, through the center of the oak and perpendicular to the growing direction of the lowermost limbs.

barbed wire in white oak, © 2011 Rachel Garwin

Rusty barbed wire protruding from the base of the white oak. The design looked similar to the common Glidden “Winner” variety patented in 1874 and widely available across America.

These waist-thick protrusions of wood would have reached towards the sun-rich pasture across the barbed fence, growing massive.  Today, however, the lowest branches are dead.  When they fall, the trunk will grow around the branch scar, resulting in a large burl.  Lower branch scars exist, but none as striking as what the future holds.  Does this lack of gigantic burls suggest that yesterday’s lower limbs were smaller?  Did the oak originally grow in less sunny conditions on that side, which reduced the amount of energy available to the tree to create huge branches?  Or had the tree simply been younger and smaller, yet unable to produce such girth?  Regardless, the branching pattern suggested that the patchy area to east and south—now growing with young, even-aged, forked white pines—was once open.

My friend claimed the oak was 300 years old, and I’d believe him based solely on the tree’s size.  The oak’s stately bearing is convincing as well.  The spreading canopy still bears a lush complement of waxy, dark green leaves; 300 can be considered middle-aged when oaks have been known to live as long as six centuries.  A relatively fresh acorn cap lay at the ground, however, suggesting the tree is still of reproductive age, or between fifty and 200 years old (though sometimes older).  Without coring the oak, we will never know for certain, and the mystery will continue.   How had I missed it so many times in the past?

fallen oak leaf, © 2011 Rachel Garwin

A freshly fallen white oak leaf lying among bits of old pine needles, maple leaves, and bark chunks on the forest floor.

The Prince of Plant Collectors and the Largest Cactus in the World

By Audrey Clark

When the Prescott College coastal ecology class for which I was a teaching assistant left the field station on the shores of Kino Bay in early January, the sun shone and the sea was calm.  We loaded the students into a couple fiberglass fishing boats and sped off toward the Midriff Islands.

Kino Bay is about a third of the way down the Gulf of California, in what is known as the Midriff Island region.  There, the coasts of Baja and mainland Mexico pinch in slightly and islands are scattered across the waist of the Gulf.  The Midriff Islands cause cold, nutrient-rich waters to well up from the trenches to the south, which feed an abundance and diversity of life.  Many bird species breed almost exclusively on islands in the Gulf of California, often just on one or two.  The Sonoran Desert blankets the land around the Gulf, so that the largest cactus in the world, the cardon (Pachycereus pringlei), towers next to the dunes and waves.

Cardon cacti are the icons of the Mexican Sonoran Desert.  They form forests, have a trunk that can be over seven feet in circumference, grow up to 50 feet tall, and can have upwards of 80 branches.  You can even climb them like trees because the aged, leathery, lower trunks lose their spines.  Cardon look very much like saguaros, those quintessential cacti popularized by Western films and Mexican restaurants.  The main difference between the two species is that a rather large saguaro might have 10 arms, whereas a cardon can easily have 80.

When we circled the cactus-covered island called Cholludo, we looked up into the backlit cardon cacti to see thirty turkey vultures sunning themselves, their silvery primary feathers glowing against their black silhouettes.  Later, we sped out to Isla San Pedro Martir, the most isolated island in the gulf, on a glassy sea.  San Pedro Martir appears perpetually covered in snow—but the “snow” is actually bird guano and the reek is, at times, choking.  The professor told us that the Yaqui Indians were once enslaved on small islands in the Gulf, forced to harvest the guano for its phosphorus, which was then used by the Mexican military to make explosives.  I thought of the sun, and the lack of fresh water, and the stench.  Now, the island hosts the northernmost breeding colony of red-billed tropicbirds and a substantial blue-footed and brown booby colony.

We sat on the gently rocking boat in a nook near shore, surrounded in the water by curious cavorting sea lions.  We took in with all of our senses the white, cardon-covered black volcanic rocks while hundreds of boobies wheeled above the island’s peaks and tropicbirds circled us like angels.  San Pedro Martir hosts only a few plant species, due to its caustic burden of bird feces.  The cardons survive somehow, even though they are coated with the stuff like paint-splattered furniture.  On our way home, a humpback opened its maw not ten feet from our boat, so that we looked down into its mouth of baleen.

A year later, I came to the University of Vermont for graduate school and was awarded a research assistantship at the university’s Pringle Herbarium.  An herbarium is like a library, but full of pressed plants instead of books.  Botanists use herbarium specimens to understand the differences between species, their ranges, population trends, and more.  Darwin used the specimens he collected on his voyage to develop the theory of evolution by natural selection.

My job at the herbarium was to dig through archives, read books, and interview former employees and then write up a comprehensive history of the herbarium.  In my diggings, I came across an article that mentioned cardon cacti.  The February 6, 1889 edition of Garden and Forest, a horticultural journal, read:

One of the most interesting of Mr. Pringle’s numerous Mexican discoveries is the great Cactus [sic] which now bears his name, and which he found during the summer of 1884 growing among the hills and mesas south of the Altar River in north-western Sonora.

The stems of this remarkable plant, which divide irregularly above the base into numerous large branches, do not attain the great height of its near relative, the now well known Suwarrow [sic], the Cereus giganteus of Arizona and Sonora.  They are sometimes, however, more than thirty feet high and thicker and more ponderous than those of any Cactus known….

Nothing more was seen of this plant until October, 1887, when Dr. Edward Palmer, the well-known explorer of Mexican botany, visited San Pedro Martin [sic] Island, in the Gulf of California, which he found covered with a forest of these trees…one of the strangest and most remarkable forests which has yet been seen in any portion of the North American Continent.

It appears from Dr. Palmer’s notes that San Pedro Martin Island…is partly covered in a deep deposit of guano, which Mexicans and Yacqua Indians are now engaged in collecting for export.  The Cereus is called Cordon by the Indians, who gather the fruit in great quantities.

The Latin name of cardon, Pachycereus pringlei, means “Pringle’s thick columnar cactus.”  Cyrus Pringle, one of the most famous and prolific plant collectors of all time, was the first botanist to collect a specimen of the cactus.

Pringle lived in Charlotte, Vermont for most of his life (1838-1911).  For the last nine years of it, he lived on the University of Vermont campus, next door to his herbarium.  Nearly every year for the last 30 years of his life, he spent several months collecting plants in Mexico.  His specimens are still admired for their completeness and careful arrangement.

Pringle collected the cardon cactus in 1884, on one of his first visits to Mexico.  When I learned that Pringle collected this cactus, I wanted to know two things: how did he collect a specimen of such an enormous cactus without mutilating either himself or his plant press?  And what did he think of his grand “discovery”?

To answer the first question, I went to the Pringle Herbarium.  On the third floor of the 200 year-old building I wandered among creaking wooden cabinets until I found the section containing specimens of Cactaceae, the cactus family.  I poked through folders of spiny specimens until I found the one containing the genus Pachycereus.  It contained one specimen, that of pecten-arboriginum.  Not P. pringlei.  I was shocked.  How could the herbarium that Cyrus Pringle founded not contain a specimen of his most striking collection?  Could it be that botanists just don’t care about charismatic megaflora as much as I do?

Then I remembered that the plant used to go under the name Cereus pringlei.  I shuffled through the Cereus folders until I found “p.”  With mounting dismay I sorted through the “p” specimens, not finding pringlei.  But then—there it was.  Just one specimen of one of the most dramatic plants on earth, in an herbarium containing over 350,000 specimens.  It consisted of a couple strips of cactus flesh and a few fruit sewn to a 12 by 18 inch piece of whitish cardboard, with a yellowed label in the lower right corner.  The label was one of Pringle’s, written in pen and ink in his barely legible hand.  The cardboard was coated in coal dust, a vestige of former herbarium heating systems.

The answer to my question of how Pringle collected the giant cactus was that rather than uprooting an entire individual, as is common when collecting other, smaller plants, Pringle simply cut a few pieces off of it and grabbed a handful of fruit—carefully.  These he squashed in his plant press (having pushed the spines sideways), dried, and then sewed onto the piece of cardboard.

What did Pringle think of his enormous cactus?  At the very least, he wanted it named after himself.  When Asa Gray, a famous Harvard botanist, immortalized Pringle in early 1884 by naming a shrub after him, Pringle wrote, “Well, I am glad not to be commenorated [sic] by some insignificant little weed under the diminutive name of Pringella.  Dr. Gray asked me if I preferred to wait to find some more showy plant; but I thought this as appropriate as anything could be….”  This was probably the first plant to be named after Pringle.  A short time later, Pringle got his showy plant, for in late 1884 he wrote to a friend about cardon: “Please throw out [the name] Cereus ponderosus; [the botanist Sereno] Watson indulged me, and gave the plant my name; it is as large as C. giganteus and only some 70 miles south of the Boundary.”

It didn’t take long for more botanists to name plants after Pringle.  He quickly gained fame for his superb and abundant specimens.  By the end of his career, Pringle had at least 4 genera, 75 species, and nearly 30 varieties and subspecies named after him.

I think Pringle loved cardon because he loved plants and desert Mexico.  He loved plants so much that he collected over 500,000 specimens in his lifetime (“I find complete happiness in this botanical work,” he wrote).  He certainly loved the desert at least as much as I do.  Though friends urged him to make his way toward lusher environs, where plants would be more abundant, he refused, saying that there was still much to discover in the desert.  In spite of the difficulty of traveling by train, wagon, mule, and on foot across Mexico’s arid landscape, into cañons and onto mesas that are still wildly difficult to access, he spent most of 26 years doing so.  In 1884 he wrote, “I spent nearly a month—March 17th to April 12th, on a trip through Sonora to the Gulf. [sic] of Cal.  It is a fearful country to travel, water scarce and forage for horses scarcer still.  It was like a race for life with us.”  He did it, I am sure, for the thrill of discovery and love of plants.

I love cardon for different reasons than Pringle.  I love cardon not just because they are dramatic—though I do love them for that reason.  I love them because they give the coastal Sonoran Desert a character and dimension unlike anywhere else on Earth.  I love them because vultures perch on them and boobies and tropicbirds circle them.  I love them because they are the biggest and strangest trees in the desert.

Time Slips

By Danielle Owczarski

Crickets sound their high-pitched hum, blaring sirens swell and shrink, sweat percolates in overlapping areas, distant music floats through the moonlit breeze, insomnia returns, a kingfisher chatters along the lake shore, a main sail flaps in the breeze – all signifying the shift to summer in Burlington. Spring has its moments with its ephemeral blooms, but with summer, we shed the last layers of clothing. White skin peeks out no longer shy, soon many shades darker and prominently displayed. We relish the summer months without the taunting of spring’s undulating meteorological moods. Like our seasonal feathered friends, we break out into bold colors and partake in the ritualistic dance of the Burlington Jazz Festival and music on the waterfront. The neighborhood druids welcome the summer solstice by gathering around the Earth Clock in Oakledge Park, drumming in the sunlight’s energy.

Midsummer festivals, boldly celebrated in pre-Christian times and still today in many cultures under an altered guise, take place around the solstice. The Oxford English Dictionary states that summer has its origins in Old English as sumor, sumere, and somera among other variations first recognized in text c. 825, referring to its role as the warmest season of the year. And while summer more accurately applies to the astronomical solstice then to the actual beginning of the seasonal and climatic change, it is understood as a time of fertility, growth, and warmth. Bonfires and heavy drinking are the most common signifiers of midsummer revelries throughout the world, the celebration linked to the birth of John the Baptist, born six months prior to Jesus. However, stripped of its religious shroud, in the silence and beauty of the early morning, summer is the celebration of energy transformed into life.

Despite the simplicity of its title, summer is dynamic, generating an ever-changing understory and flow of biotic change. Those of us who work outside during this time of year follow the influx of hatching insects good and bad. Appearing first are the black flies, followed by the deer flies and mosquitoes. While the former two usually abide by shorter seasons, the mosquitoes continue hatching throughout the late summer months. Overshadowed by the annoying, small flying insects are those who act as predators keeping them at bay.

Dragonflies, unbeknownst to some, live most of their lives (up to four years) as armored nymphs in calm aquatic environments. The warm sun of early summer heats the waters, enticing the mature nymphs to the surface where they crawl out and clasp themselves to tall grasses, wood, and stone. Here they begin their hatch. Attached to a cattail leaf above the water, the nymph’s exoskeleton begins to dry and crack along the back where the dragonfly emerges, compressed and translucent, expanding into a world of bug feasts, avian maneuvers, sex, and egg laying. Their terrestrial phase occurs no longer than two months causing their numbers to dwindle by late summer.

Those of us working inside this time of year suffer through the mocking rays of light filtering through paned glass windows. The vigor of those coming in from outside tickles the nerves and draws conscious thought away from tasks and into daydreams of lake breezes on bare skin, lush winding hiking trails, and the transforming hues of clouds low on the horizon. For most of us trying to take advantage of the summer day, a strange phenomenon occurs, while the length of the day in relation to sunlight increases, time seems to move more quickly. Weekends fill with social obligations, and the list of things to do and places to visit become too numerous to accomplish. Summer spurs the endless chase of the elusive present moment.

In nature, as the season progresses, the once electrifying greens of spring begin to dull. Before we know it, tomatoes are ripening into deep reds and purples, and the goldenrods and asters are blooming. In town, the college students are moving into their dorms and young children board the yellow bus while we wait patiently in traffic. Some welcome the change with anticipation of harvest festivals, cider donuts, and corn mazes, while others feel depressed by the notion of winter’s encroaching darkness. Despite our resistance, the mayfly, stonefly, and caddisfly, each year during this time, hatch, lay their eggs, and die. The brook trout rise to eat, and a small red maple leaf flutters, dropping slowly to the water’s surface.