spring

The Remarkable Hummingbird Tongue

/ Mike Fitz / 1 Comment

In the northern third of Maine spring weather is fitful, and I sometimes wonder if winter will ever break its hold. Eventually, though, usually in mid March, snow cover begins to thin as the sun travels higher in the sky and daylight hours lengthen. Around this time, maple sap runs heavy. As April arrives the hazelnut, speckled alder, and aspen (or “popples” as they are locally called) break bud as the ground thaws in earnest. I might see my first dark-eyed junco of the year about that time, followed by flickers and sapsuckers who drum from the trees as they establish nesting territories. Wood frogs, spring peepers, and salamanders wake from hibernation and migrate to their breeding pools on rainy nights. The warblers return in May along with early ephemeral wildflowers and the first expanding tree leaves in the canopy.

Although I welcome these changes like a reunion with friends, there’s one event beyond any other (even the appearance of biting insects), that to me signals the full arrival of spring—the return of hummingbirds.

A male ruby-throated hummingbird.

On May 12, I was treated to the first hummingbirds of the year at my feeders. Only one hummingbird species, the ruby-throated, nests in the northeast U.S. and southeastern Canada. The ruby-throats that establish summer residency near me may have migrated from wintering areas in Central America, probably by flying over the Gulf of Mexico before making their way farther north.

With a heart that pounds at several hundred beats per minute and wings that buzz at a too-fast-to-see pace, an active hummingbird is a powerful metabolic furnace. While insects and spiders are important foods, the fat and protein the bird ingests from invertebrate prey goes only so far in its effort to sustain their exceptionally high metabolism and energy-intensive flight. An active hummingbird’s metabolism is so high that it must eat about half its body weight in sugar each day, and it digests sugar so rapidly that it essentially refuels in flight.

The energetic costs of this lifestyle are great, so if you are a tiny bird that weighs only a few grams then it pays to be as efficient in your nectar gathering as possible. For a hummingbird, the process begins with an ingenious adaptation of the tongue.

Scientists long assumed that hummingbirds utilized the passive work of capillary action to drink nectar—stick your tongue into a flower, contact nectar with it, and allow the liquid’s surface tension to coat the tongue. However, in a 2011 paper published in the Proceedings of the National Academy of Science,* Alejandro Rico-Guevara and Margaret Rubega discovered that that a hummingbird tongue works in a much more efficient manner.

A hummingbird’s tongue is forked, somewhat tubular, and supported by stiff rods. That anatomy has been known for quite some time, but Rico-Guevara and Rubega found that the tongue utilizes no capillary action. Instead it is a shape shifter, a fluid trap, and in the author’s words, “a dynamic liquid trapping device.”

As the bird sticks its tongue out the tips remain adhered together. At this point, it looks like a long pin. Once the tongue contacts nectar, though, the real magic of the tongue’s anatomy begins its work. First, the tongue splits as curved lamellae (parallel hair like structures) along the tongue tips unfurl in the liquid.

GIF of
In nectar, a hummingbird’s unrolled tongue tips substantially increase the surface area in contact with the nectar. Timestamp is in milliseconds. Movie SM01 from (2011) Rico-Guevara and Rubega.

As the bird retracts its tongue, the lamellae re-furl over the supporting rods and trap a tube of nectar inside each tongue tip.

A view of a hummingbird’s tongue re-furling as it is withdrawn from nectar. Air is on the left. Liquid is on the right. Timestamp is in milliseconds. Movie SM03 from (2011) Rico-Guevara and Rubega.
A closer view of the tongue re-furling. Air is on the left. Liquid is on the right. Timestamp is in milliseconds. Movie SM04 from (2011) Rico-Guevara and Rubega.

Amazingly, the tongue’s transformation and liquid trapping properties are driven not by muscles, but by fluid and gaseous forces acting directly on the tongue. The tongue’s structure is hydrophilic, so when the tongue contacts air the lamellae curl around the nectar and traps it inside. The bird releases the nectar by squeezing and slightly flattening the tongue as it is pulled into the bill.

Nectar can be a difficult to access food. Hummingbirds exploit it like no other bird because they can hover in flight and, as a group, have diverse beak lengths and curvatures to probe flowers of different sizes and shapes. They are also clever enough to trapline—that is, they’ll visit the same food sources like patches of flowers on a regular basis to minimize competition and maximize nectar availability.

But knowing how specialized the hummingbird’s tongue is, I’ll never look at a feeding hummingbird the same way. The hummingbird tongue, long thought to be a passive part of the process, is a superb adaption that plays no small role in helping these tiny birds live a large life.

*The paper is a fascinating bit of natural history and is open-access, so I encourage you to read if you want to learn more about this topic.

The Swarm

/ Mike Fitz / 3 Comments

Recently, I found myself in the middle of an insect apocalypse as honeybees swarmed into my neighborhood.

“Mile by mile, city after city, it moves; leaving in its wake a path of destruction.”

Well, the event wasn’t quite like that, but I was still fascinated.

Swarming is a normal behavior for honeybees. In spring, when food is abundant, a colony may outgrow its home. Workers begin to produce new queens and the old queen departs with up to two-thirds of the colony. These swarms can contain thousands of individuals.

The swarm departs the old hive before they’ve found a new home. While scouts search for a suitable site, much of the swarm forms a cluster around the queen. This is when honeybees clump en masse.

swarm of honeybees clumped together on a tree branch

A honeybee swarm clumped together on a tree branch in Arkansas. Photo courtesy of Mark Osgatharp and Wikipedia.

Scout bees dance after they return to the swarm to communicate the direction and distance of potential home sites. Based on the vigorousness of the dance, the swarm then decides collectively on where to make their new home.

Unfortunately, I missed my opportunity for a bee beard, as the swarm had already found its new home by the time I saw it. The bees were just beginning to settle on the tree and move into the cavity between the fused trunks of two western red-cedars. As if queuing up to enter a stadium for a sporting event, the bees landed on the tree trunk and crawled inside. After a half hour, almost no bees remained outside the cavity.

swarm of bees at narrow entrance to a tree cavity

The swarm moves into the tree cavity. At this time, most of the bees are still outside it.

a few dozen bees at the narrow entrance to a tree cavity

Fifteen minutes later, most of the bees had entered the their new hive site.

Standing near the tree in shorts and t-shirt, bees flew all around me, yet only one made a mistake and ran into me (I wasn’t stung). While swarming, honeybees aren’t concerned with protecting larvae or honey stores. They’re concerned with finding a new home. As long as I didn’t make any aggressive attempts to disturb them, I could watch them quite safely.

Now I have some new neighbors. Thankfully, I don’t think they pose a threat to nuclear power plants.

Spring cycling along the North Cascades Highway

/ Mike Fitz / 6 Comments

Last June, I wrote about cycling to Rainy Pass on the North Cascades Highway. For half the year, however, this road is closed as snow accumulation and avalanche danger, especially, become too great to keep it open. On weekends in spring, when road crews pause their work to clear snow and avalanche debris, the highway opens to bicyclists, so last Friday I took a rare opportunity to ride a car-free road. I found springtime fully fledged at low elevations in the North Cascades and winter’s legacy still holding a firm grip on the high country.

At low elevations, near the town of Newhalem, the weather and vegetation reflect mature springtime conditions. Hummingbirds seek nectar from red-flowering currant, deciduous plants are nearly fully leafed-out, and the ground is snow-free.

pink flowers on shrub

Red-flowering currant (Ribes sanguineum)

Heading east through Ross Lake National Recreation Area, the road climbs most steeply where it skirts the three hydroelectric dams on the Skagit River. Even here, at elevations below 1000 feet, avalanches will sometimes crash across the road when winter conditions are right.

gully on mountainside

In February 2017, a large avalanche crossed the highway at this location, trapping a few dozen people on the other side for several days.

view of avalanche snow on road

An avalanche covering the road at the same place on February 25, 2018. Photo courtesy of Washington State DOT.]

After fifteen miles of riding, beyond Diablo Lake…

View of lake and mountains

…I reached the Ross Dam trailhead where the highway remained closed to cars.

gate across highway. sign reads "Active slide area proceed at your own risk" and "Stop"

Freed of the stress of close encounters with cars, cycling on car-free roads is wonderfully relaxing. Even as I remained reasonably alert for hazards and other cyclists, I was able to do stupid things I’d never try when sharing the road with motor vehicles—like riding down the centerline while recording video.

GIF of road and surrounded by mountains and trees

For me, the car-free environment also promotes stopping where anything catches my attention. Ascending higher into the mountains, I watched as the vegetation became less and less green. From a certain phenological perspective, I was moving backwards through time. By the time I reached 2,500 feet in elevation, most of the raucous birdsong of the Skagit lowlands disappeared and deciduous plants were just breaking bud.

green flowers at the end of a maple branch

Big leaf maple has already finished blooming at low elevations along the Skagit River, but it was still in full flower around 3000 feet in elevation along the highway.

Around highway mile 150, about 15 miles beyond the gate at Ross Dam and 4,000 feet above sea level, snow continuously covered the ground. It only became deeper as I pedaled farther. Just a couple of miles shy of Rainy Pass, where state road crews had halted their work for the week, snow remained five feet deep on the road.

bicycle leaning against snow bank with one lane of plowed highway

 

bicycle leaning on five-foot high snow bank

The end of the plowed road on May 4, 2018.

As it melts, the snow provides much needed water to streams and rivers in a mountainous region where summer drought is common. For many plants though, the deep snow hinders growth well into summer. On the day of my ride, temperatures hovered in the 60s˚ F, certainly well within the temperature tolerance of plants in the Cascades, but the deep snow keeps the underlying soil cold and dark. Under these conditions, most plants have to lie dormant until growing conditions improve. In the North Cascades, where snow accumulation is so deep and extensive, this set of conditions creates a perpetual spring season on the margins of the snow pack. This gives wildlife like deer and bears the opportunity to eat young and nutritious plants through July and August.

yellow-flowered lily

Yellow avalanche lilies (Erythronium grandiflorum) are currently blooming in the Diablo Lake area. More commonly associated with meadows at higher elevations, these perennials have a short growing season. They begin to grow from a perennial bulb as soon, and sometimes even before, snow cover melts away to take advantage of ephemerally moist soils. By late July, the soils where this specimen grows will have become powdery dry, but at higher elevations this species will still be in flower.

new leaves at the end of small twigs in shaded forest

Late last July, long after I began to feast on blueberries at low elevations, blueberry plants in a snowy portion of Pelton Basin has just begun to leaf out. Late season berries are an important food source for bears this area.

Even during this ride into the middle elevations of the North Cascades (the highest non-volcanic peaks here top out over 9,000 feet tall), it was easy to see how snow exerts a significant influence on the landscape. The week of my ride, road crews reported nine feet of snow at Rainy Pass (el. 4,855’). In a couple of months, when tender plants like yellow avalanche lilies have withered and dried at lower elevations, I can ride up here again and find a microcosm of spring along the edge of the remaining snow.

view of snow-capped mountains and coniferous forest

First Flowers

/ Mike Fitz / 1 Comment

Spring has officially arrived in the northern hemisphere, and southwestern facing slopes in the North Cascades, especially near Lake Chelan, are thawing quickly. This is where I seek the first herbaceous and mossy greenery of the year.

leaves and moss on rock

Green leaves and vibrant moss are a welcome sight after a snowy winter.

At the lakeshore, approximately 1100 feet (335 meters) in elevation, deep snow and relatively mild winter temperatures (daily lows for December through February average around 25˚F/-4˚C) prevent soil from freezing significantly. During late winter and early spring, sunlight directly strikes the southwestern facing slopes along the lake. Bare rock and tree trunk create heat islands that further warm the soil and melt remaining snow. The first wildflowers of the season bloom here, taking advantage of conditions that higher elevations will not experience for months. Two species are just setting blossoms now.

wildflower with umbel of yellow flowers and pinnate leaves, among other small vegetation

Wyeth biscuitroot (Lomatium ambiguum) near Stehekin Landing.

wildflower with umbel of white blossoms and pinnate leaves

Geyer’s biscuitroot (Lomatium geyeri) near Stehekin Landing.

Biscuitroot (Lomatium sp.), also called desert-parsley, is a large and widespread genus of plants in western North America. The species I found are not exclusively restricted to the rocky areas near the lake, but these individual plants have found an ideal early season microhabitat. The slopes where these plants grow are very warm, although it may not seem that way when they are dripping with snowmelt.

bright green moss, dripping with water, on side of rock

Anyplace it is exposed near upper Lake Chelan, moss is saturated with snow melt.

By the end of June, perhaps even before, these plants will be parched by low humidity and scorched by high daytime temperatures. The soil, instead of wet and clumpy, will become dust. Flowering plants in this location do their business quickly—blooming and setting seed before the soil completely desiccates and ground temperatures become too hot. They get ahead now, because conditions allow them to. Up valley and higher on the mountainsides, under the snow, other members of their respective species are waiting for their own moments in the sun. It’s only a matter of time.