The Kinglet’s Golden Rule

“I am gladdened to know that a population of these wraiths of the forest thrives. When I’m  in the warmth of my cabin and hear gusts of wind outside that moan through the woods and shake the cabin on wintry nights, I will continue to marvel at and wonder how the little featherpuffs are faring. They defy the odds and the laws of physics, and prove that the fabulous is possible.”

-Bernd Heinrich, Winter World (2003)

In 1847, a German biologist named Carl Bergmann noticed a pattern among warm-blooded animal species. He found that, in general, larger species tend to occur in colder environments, while smaller species appear in warmer ones. The examples are legion in the Northern Hemisphere: Kodiak bears in Alaska, gray wolves of the tundra, polar bears and moose and ravens throughout the sub-Arctic-all among the largest species in their respective clades. Gyrfalcons, great gray owls, and snowy owls are similarly outsize for their ilk, and are all found at northerly latitudes. Bergmann’s “rule”, as it came to be known, is based on a simple law of thermodynamics: smaller objects lose heat faster than larger ones, due to their higher surface area-to-volume ratios. Heat is absorbed and lost from exposed surfaces. Bodies retain heat, and bodies with more volume retain more heat. Thus, an animal with a lower surface area-to-volume ratio radiates less body heat per unit of mass, and hence stays warmer in cold climates.

Bergmann’s rule is more of an empirical generalization, a biogeographical principal that not invariably, but in most cases, holds true. It applies mainly to homeotherms, those animals that regulate body temperature internally. A 2003 Israeli study published in the Journal of Biogeography found that, out of a sample size of 94 bird species and 149 mammal species, about 72 percent of the birds and 65 percent of the mammals followed the rule. Of course, rare is the rule that’s lacking in exceptions, and Bergmann’s has more than a few. Of all these rule-flouters, though, nothing tops the wee golden-crowned kinglet in its arrant, crest­ waving flagrancy.

In the coniferous forests of North America there reigns a lively little king, a ruler that lives above and beyond Bergmann’s rule of biogeography. One of the smallest passerines, the golden-crowned kinglet is hummingbird-sized, olive­ gray in plumage and gregarious in nature. Small flocks pass through trees as quickly and subtly as the breeze, pausing briefly to zeet-tzeet-tzeet! ” at one another before disappearing into the foliage. They are ardent insectivores, flitting from boughs and shrubs–sometimes hovering for an instant at a twig-tip, sometimes hanging upside-down from branches-gleaning moth larvae, spiders, and springtails, which they consume constantly. The kinglets in Oregon are mostly year­-round residents, braving the winter chill to forage for bugs where other birds had long since turned tail southward.

A kinglet weighs five to six grams, about as much as two pennies. In size and mass, it is comparable to two ping-pong balls glued together, with wings. The kinglet’s surface-to­ volume ratio is appreciably high–the bird is both minute and almost weightless, a bad combination for a cold-dwelling homeotherm. Also of significance is the fact that a kinglet’s brain accounts for 6.8 percent of its entire body weight (in humans it’s 1.9 percent); and if kinglet brains require anything like the energy human ones do (about 20 percent of total calories), then the brain drain is costly, indeed. How then does the kinglet hack the winter months, especially in parts of its range where nighttime temperatures plunge to -40 degrees Fahrenheit?

First, it eats ravenously, continuously, for as long as the day holds light. An animal so slight, losing so much heat to its  frigid surroundings, simply cannot afford to let its metabolism idle. Kinglets must consume two to three times their weight in insects per day to maintain internal temperatures of 110 degrees-below this threshold hypothermia threatens and death isn’t far off. They don’t take handouts, either: kinglets, unlike many overwintering passerines, usually won’t visit bird feeders, no matter the contents. They prefer live fare, spending every waking moment in pursuit of it.

Kinglets also come well-dressed for the weather. The birds, as it turns out, are mostly filler­ their insulative feathers make up much of their puny, poofy bulk, extending to almost an inch from the body when fluffed up against cold. Bernd Heinrich, author and professor of biology at the University of Vermont, found that a plucked kinglet–the bird even further reduced in size, and infinitely sadder-looking–loses heat at rate 250 times faster than a feathered one. Compared to a similarly defrocked human, the kinglet cools 60 times faster, being so small. Clearly, the kinglets wouldn’t survive a winter minute without their regalia. Heinrich, working in the bitterly cold northeastern U.S., also found that the internal temperature of the birds would at times differ from the outside temperature by as much as 170 degrees Fahrenheit-an incredible contrast, and a testament to the feathery powers of down.

Despite their canny adaptations, kinglet populations often experience high mortality in colder months, simply for the fact that winter is a harsh season in which to make a living. There are cold snaps, food shortages, nights of freezing rain. Heinrich writes that the kinglet “has no magic key for survival in the cold winter world of snow and ice. Those that live there are lucky and do every little thing right. The odds of surviving the winter are slim…”  What the kinglets lose in winter, however, they more than make up for in spring: come April, kinglet pairs build teacup-sized nests and produce five to eleven eggs, more than double the number in a typical songbird clutch. The female hatches them, leaves daycare duties to the male, and then goes off to foster a new brood of equal size (sometimes with a different male).

Kinglets in winter are a marvelous sight, their movements frenetic, flighty, and all too fleeting. They are industrious while others lie torpid, fluttering about in their desperate search for calories and warmth. Staving off starvation, living from beakful to beakful, kinglets don’t play by Bergmann’s rule, and in fact their existence almost makes a mockery of it. In the deeply senescing woods, where much of life is put on ice, these little sovereigns are wide awake.

October 27 Work Party Recap

Saturday, October 27 was a lovely, warming Fall day at our Malheur National Wildlife Refuge. Our hard-working crew, fueled by coffee and snacks, was ready to get to work. Chatting up a storm (Spurge and Larry in particular!), it didn’t take long for jackets and sweatshirts to start being shed. The focus of all this energy was to clean up all the hugely overgrown weeds and shrubs surrounding our new Crane’s Nest Nature Center.

Alice single-handily tamed the lilac hedge on the south side of the yard, removing load after pickup load of dead wood.

Larry and Spurge became our experts at attacking and removing the huge root balls that were flush with the foundation. As a result, the original iron grates covering the foundation window wells, not only now allow more light into the basement, but are handsome, historic pieces to admire. The window wells are also now clear of years of leaves and debris.

Lisa Sanco, Program Manager for Worthy Garden Club, our Pollinator Garden sponsor, corralled all the cottonwood leaves into pile after pile which soon found their way into the back of the Refuge’s pickup headed for the debris pile.

The weeding crew, especially Jody Newman, found all the buried flagstones that some of us remember from many years past. They found a new home next to the east door filling a small space between the door steps and the first foundation window well that is only suitable for some new ground cover.

Cay, Susan and Jody just worked and worked, weeding, thinning and transplanting several plant clumps on the east and along the south end of the building. Many were moved to the south end of the building but a more appropriate distance from the building’s foundation.

This Spring, when we gather to build and plant our Worthy Garden Club Pollinator Garden, we will also add some flowers and plants in these newly created beds. hey will support our hummingbirds and pollinators with more color than the former residence has seen for many years. So put April 11-14 on your calendars and join us* in building our largest project to date, a 10×18 foot raised bed, garden.

Thank you all for your hard work and love for our Refuge! Have a lovely Winter and see you in the Spring!

 

*Watch the monthly newsletter for an opportunity to sign up for this volunteer project.

Beaver or Muskrat?

The vast marshes and riparian thickets of Harney Basin are a sanctuary for water-loving wildlife, from the scores of birds, insects, amphibians and fishes using its waterways to more than 50 native mammal species. Of these mammals, several are specially adapted for the life aquatic, including the American beaver (Castor canadensis) and the muskrat (Ondatra zibethicus).

From time immemorial, beaver and muskrat were hunted by Harney Basin’s indigenous peoples for food and pelts. When the first Euro-Americans arrived in the basin in the 1820s, their primary pursuit was fur, especially that of beaver and muskrat, for use in garments.

Since both species occur at Malheur Refuge, often in the same habitats, it can sometimes be tricky to tell them apart–particularly at a distance, and if the animal is partially submerged. Owing to their similar lifestyles, beaver and muskrat share several physiological and behavioral traits. Both semi-aquatic rodents possess webbed back feet and thick, brownish, water-resistant fur. Both can remain submerged for up to 15 minutes at a time. Both are most active at night, feeding predominately on vegetation, and neither hibernates during the winter. Both build their dwellings at water’s edge using local plant materials.

While beaver and muskrat have much in common, there are clear differences between the two. Most know that the beaver’s tail is distinctively wide and flat, covered not in hair but scales. The muskrat’s tail, while similarly scaly, is long, thin and slightly flattened vertically. While swimming, a muskrat’s tail sweeps side to side, like a fish’s; the beaver’s paddle-like tail pumps up and down, like a dolphin’s.

Beavers are much larger than muskrats, weighing between 35 and 60 pounds. A full-grown muskrat reaches only 4 pounds. When swimming, a muskrat usually shows its entire body near the surface; beavers show only their heads. The ears of a beaver are also more visible than those of a muskrat.

The waterside dwellings of beaver and muskrat are often noticeably different in their construction. A beaver lodge is typically dome-shaped, employing copious amounts of mud daubed over sticks and logs. A muskrat lodge uses lighter materials (such as bulrush and cattail stalks) which are piled over a solid foundation, such as a tree stump. Sometimes these rodents leave tracks in the mud near their lodges: A muskrat’s drooping tail leaves long, skinny marks as it walks, while a beaver’s wide tail tends to drag through part of its tracks, obscuring them.

No matter the season, wildlife watchers at Malheur Refuge may chance upon seeing one or both of these water-loving rodents plying marshes, sloughs or river channels during their visit. Hopefully this blog post helps to ease any identification challenges!

The High Desert Solitaire

As the high-desert nights grow colder and the days shorter, most birds leave the Harney Basin for warmer climes. Some hardy species, such as the great horned owl, Northern flicker and song sparrow, resolutely stay put all winter, while others migrate into the basin to seek reprieve from even harsher conditions. One of these winter visitors is the Townsend’s solitaire.

Beginning in late August, the foothills of the basin, filled with juniper trees and flanked by lichen-covered rimrock, ring with the flute-like calls and songs of Townsend’s solitaires. In our region, these thrushes migrate down from the mountains to take advantage of food sources at lower elevations through the winter.

Powdery gray overall, with tan wing bars, white outer tail feathers, and a dainty white eye­-ring, the unassuming solitaire would likely go unnoticed if it weren’t for its exuberant voice, calling and even singing in the dead of winter. Both sexes look alike, and both sing year­-round. The song of the solitaire has been described as “[an] infinitely fine and sweet rendering of mountain music…in rippling cadences not shrill, but in an infinite number of runs and modulated trills, dying away again and again to low plaintive whispering notes…” (Forrest S. Hanford, 1917). To establish and defend its territory, the solitaire’s piping one­-note call is broadcast loudly, as often as 30 times a minute.

First collected by naturalist John Kirk Townsend along the lower Willamette River in 1835, the solitaire exhibits a confounding mix of traits. Its drab plumage and habit of sallying forth to capture insects in flight is reminiscent of tyrant flycatchers, but its melodious voice and speckled young betray its kinship with thrushes. Townsend collected only one bird, a female–but this was enough for John James Audubon to describe the species and name it in his honor in 1838.

Townsend’s solitaire is a habitue of montane forests and meadows, found year-round in much of the lntermountain West. Alongside the mountain bluebird, these thrushes are most at home in high, mountainous country.

In the summer, solitaires frequent high-altitude forests, sometimes ranging beyond tree line in search of invertebrate prey. Perching at the tops of trees or shrubs, these birds fly out to capture insects mid-air with an audible snap of their bills; they also perch closer to the ground, in the manner of bluebirds, to scan the forest floor for prey.

These birds nest on or near the ground, in any crevice with a sheltering overhang. Solitaires are known to build nests under logs and stumps, in the lees of boulders, or along steep roadcuts and trails. In the lntermountain West, solitaires nest at elevations ranging from 7,000 to 10,500 feet above sea level; at their northerly breeding areas in northwestern Canada and Alaska, nesting occurs at much lower elevations.

By autumn, most solitaires migrate to the lowlands to subsist on winter fruits. In our region, solitaires are particularly dependent on the “berries” (actually the modified female cones) of juniper trees. Solitaires of both sexes become fiercely possessive of prime juniper trees in winter, and may chase away not only other solitaires but other fruit-eating birds. This is where the solitaire earns its name: perching high and alone in a prime juniper crown, sharply proclaiming its territory and warning off interlopers.

This winter, look for the solitaire broadcasting its sweet soliloquy throughout the basin’s foothills, or anywhere where fruit-laden trees or shrubs are abundant.

The Incongruous Lewis’s Woodpecker

Besides gnarled Western junipers, non-native Russian olives and the occasional grove of Fremont’s cottonwood, there are few real trees to be found at Malheur Refuge. Despite this, five woodpecker species show up regularly at scattered locations throughout the Refuge, often associated with those intermittent stands of trees. One of those species is the Lewis’s woodpecker (Melanerpes lewis), an anomaly in an already distinctive family of birds.

Lewis’s woodpecker is fairly big for a woodpecker, intermediate in size between a robin and a crow. The adult plumage of both sexes is a unique mix of greenish-black above and pinkish below, with a gray collar and dark red face. Like other woodpeckers, this species has stiffened tail feathers and zygodactyl feet, which help them move about on vertical tree trunks. Their bill is stout and tapered like most woodpeckers’ bills, if a tad thinner. But a couple of behavioral adaptions make the Lewis’s woodpecker stand out from its congeners.

First is their flight. Unlike the undulating tack adopted by most woodpeckers, the Lewis’s practices a slower, more direct flight, often punctuated by short glides. Their size, dark coloration and flight pattern are reminiscent of a crow—as is their willingness to fly across open country, instead of from tree to tree as with most other woodpeckers.

Second, in spring and summer the Lewis’s woodpecker forages like a flycatcher, sallying forth from branches, wires and posts to capture insects in flight. Their aerial agility rivals that of flycatchers as well, complete with sharp banks, sudden turns and thrilling bursts of speed. Lewis’s woodpeckers also glean insects from tree bark, but rarely do they engage in the stereotypical woodpecker habit of excavating dead wood for boring invertebrates. Their diet switches to fruit and seeds in winter, particularly acorns, which they stash in the corrugated bark of trees such as cottonwoods.

This woodpecker’s habit of flying about conspicuously did not escape the notice of Meriwether Lewis, who first encountered the bird in Idaho during the summer of 1805 while on the famous Lewis and Clark expedition. “I saw a black woodpecker (or crow) today; it is a distinct species of woodpecker; it has a long tail and flys [sic] a good deal like the jay bird,” he wrote in his journal. Years later, working with skins brought back by the expedition, the ornithologist Alexander Wilson formally described the species and named it after Lewis.

At Malheur Refuge, Lewis’s woodpeckers are seen during spring and fall migration, moving along a southwest-northeast corridor between breeding and wintering areas in forests beyond Harney County. Oftentimes these woodpeckers are more numerous at the Refuge in fall than in spring, and the height of their fall migration occurs in September, rarely extending into early October.

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