Rigor Vitae: Life Unyielding

Wednesday, January 31, 2007


The mercury in Salt Lake City is beginning to poke its silver snout into the positive Celsius digits, breaking a cold snap that's kept me cowering indoors for most of the past three weeks. Outside, the deep torpor of reptiles and amphibians will last well into March. Visible mammal life is restricted to a couple of hardy Red Squirrels (Tamiasciurus hudsonicus) that venture briefly from their dreys during the warmest hours to fuel up on cached pine nuts, and the more numerous House Mice (Mus musculus) that find relative warmth in my woodshed and composter. Meanwhile, birds, cloaked in insulating feathers, are conspicuous through the coldest days. Best protected are the gulls, loons, grebes, and others whose foraging requires prolonged contact with cold water. The insulating and water-repelling properties of duck and goose feathers are legendary, and they leave their owners well-equipped to float, warm and dry, upon the iciest waters, propelled by naked feet that can remain submerged without much heat loss. The arteries and veins of the legs run alongside one another, allowing heat from the arterial blood to diffuse into the cold venous blood, preventing major heat loss through the feet. Such heat-exchange systems are fairly common in nature, and are most sophisticated in certain poikilothermic animals. A device based on the same principle ventilates my studio with outdoor air that's cooled in the summer and heated in the winter from the exhaust duct. The circulation to the feet is also temperature-regulated; in extreme cold, blood flow is restricted.

Being close to the brain, the naked parts of a bird's head are especially prone to dangerous heat loss. Temperature is regulated by tiny connections between arteries and veins, called arteriovenous anastomoses, in the eyelids and bill, and by a heat-exchange system beneath each eye called the Rete Ophthalmicum, which is peculiar to birds. Blood to the bill is also regulated by temperature-sensitive vein restriction. These specialized circulatory structures are especially well-developed in Arctic diving-ducks like Scoters (Melanitta spp.) and Eiders (Somateria spp.). A recent news story told of a Ring-necked Duck (Aythya collaris), shot by a hunter and refrigerated, that regained consciousness. The surprising part of the story was not that the bird survived the modest cold of a refrigerator for two days, or even the limited oxygen, but that the hunter evidently planned to eat her after leaving her ungutted for two days.

In cold weather, birds can generate a substantial amount of heat by shivering, particularly in their pectoral muscles. Simple behavior like facing the wind, fluffing the feathers, pulling one leg up into the flag feathers, or tucking the bill into the feathers of the back, can do much to minimize heat loss. Group huddling during cold weather is a common tactic for keeping warm; even among birds that aren't particularly social. Warm microhabitats may also be sought, including caverns, thick conifers, tree holes and buildings. Many pheasants, grouse and partridges are particularly fond of tunneling into deep snow.

Because of their higher metabolic rates, birds are forced to spend more time and energy foraging than the average mammal—an expensive activity when over 90% of your metabolic energy is going toward maintaining body temperature. The ability of birds to adjust their metabolism is just beginning to be understood. When Edmund Jaeger discovered a hibernating Common Poor-will (Phalaenoptilus nuttallii) in 1946, ornithologists were forced to re-think their notions of bird metabolism. By lowering their body temperature by as much as 35ºC, Poor-wills are able to devote far less energy to keeping warm. These remarkable birds can actually fly while their body is as cold as 27.4ºC. (normal temperature is about 40ºC.). As researchers have studied this phenomenon, they've found that Poor-wills are particularly prone to torpor, and regularly enter it for short periods during cool summer nights. It appears that many goatsucker species, including the Whip-poor-will (Caprimulgus vociferus), are incapable of metabolic adjustment, while others, like the European Nightjar (Caprimulgus europaeus) and even the one-pound Tawny Frogmouth (Podargus strigoides), seem to enter torpor regularly, although so far, no bird has been found to “hibernate” as effectively as the Poor-will.

Unlike their relatives the nightjars, owls appear to be unable to regulate their metabolism in any meaningful way. My own observations lead me to consider Barn Owls (Tyto alba), the most nightjar-like of American owls, to be one of the most cold-sensitive bird species that regularly winter in my area. During severe cold, it's not uncommon to find their frozen corpses hanging in trees. How some other owls are able to tolerate cold as well as they do is still a mystery to me. Great Horned Owls (Bubo virginianus), our earliest nesters, are already courting. As a kid, I remember waiting for the school bus, listening to their courtship hoots in -20ºF weather. The ability of young altricial birds to thermoregulate is generally next to zero, but the mortality of Bubo chicks to cold seems to be inconsequential.

Besides the nightjars, many swifts and hummingbirds are able to drop their core body temperatures radically. Because of their high metabolic rate (a resting hummingbird burns about 5 times as many calories as a resting sparrow), hummingbirds would have trouble surviving their nightly fast without becoming torpid. At night, a hummer can drop its body temperature by 20ºC or more, breathing but a couple of times each minute, instead of the regular 400, its 500 heartbeats reduced to 30. An hour before dawn, the bird begins to stir, shivering to raise its core temperature. Within half an hour, its metabolism is back to normal.

This nightly torpor enables hummers not only to survive a cool summer night, but rather harsh extremes. The particularly foolish young Black-chinned Hummingbird (Archilochus alexandri) pictured above failed to migrate (possibly because it found backyard hummingbird feeders still being filled), and was photographed before an attractive little snowbank backdrop by my friend Hillary on January 7. Hillary put out warm sugar water for the bird, but the mercury plummeted shortly after the photo was taken, and I'm sure the poor little fellow's torpor soon became permanent.

Only a fraction of bird species have been tested for metabolic regulation, but some degree of ability seems to be fairly widespread. Among passerine birds, swallows and sunbirds (Old World convergent analogs of the hummingbirds) appear to achieve the lowest temperatures. Some degree of metabolic reduction has been recorded in chickadees, doves, condors, birds of paradise, and numerous other groups. Some diving birds appear to enter similar states while submerged. Hawks and falcons will lower their basal temperature during cold weather if they become too lean, although this is a stressful last-ditch effort at avoiding starvation, that falconers have understood for centuries.
upper: RED-BREASTED MERGANSERS (1989) acrylic 7" x 9"
second: Poor-will photographed by CPBvK in Tooele Cp., UT 1983
third: HUNGRY EYES--GREAT HORNED OWLETS (2005) acrylic 30" x 22"
fourth: BLACK-CRESTED COQUETTE (Lophornis helenae) (1999) acrylic 10" x 8"
lower: Black-chinned Hummingbird photographed by Hillary White in Salt Lake Co., UT 1-'07

Monday, January 29, 2007


When I was a youngster, an arena called the “Salt Palace” was the place to watch big name popular musicians perform—the kind of artists you can often see today in far more intimate settings. I saw dozens of great acts there, starting with Iron Butterfly when I was ten. By the early eighties, I'd lost all interest in stadium concerts, so it barely registered upon my consciousness when an improved stadium was erected about 15 years ago. Using Space-Age materials unavailable when the Salt Palace went up, the new structure, christened the “Delta Center,” represented a new high in cramped, uncomfortable seating. The old arena's acoustics were dreadful, and none of us imagined that a building could tear apart sounds and reconstruct them in a less recognizable form, but the Delta Center's engineers did a magnificent job of attaining that goal. I actually entered the new building but once: when a summer cloudburst moved a 1993 James Taylor concert indoors at the last minute. In keeping with the current rage for stadia to change corporate hands, the Delta Center was recently renamed to reflect a new patron, Energy Solutions, a research & development firm mainly known as the manager of a low-level nuclear waste dump in the desert to our west. The new name seems unpopular with the locals (as if Delta Airlines produced less pollution than Energy Solutions), who've come up with numerous clever nicknames for the arena such as “The Tox Box” and the “Radium Stadium.”

It's recently been brought to my attention that professional sports are played here in Salt Lake, quite often inside the very buildings I've rambled about here. I have nothing against spectator sports, as long as the spectator isn't me. The only reason these jumbled thoughts have come to surface is that I plan to enter Energy Solutions Arena this evening, for the first time in a decade and a half. My old pal John Flanders will play the Star-Spangled Banner on the saxophone tonight before a Utah Jazz game, and I'll be there to witness the whole thing—the first basketball game I will have ever watched without participating in it. I have never painted pro basketball either, and the closest thing I can find to illustrate this post with is this little South American poison frog, Dendrobates duellmani, perched upon a leaf that's roughly the color of a traditional basketball.
illustration: SPOT-BELLIED DART FROG (1997) acrylic 7" x 7"

Friday, January 19, 2007


When it comes to icons of American forest conservation, most of us think of birds like Spotted Owls, Marbled Murrelets, or Red-cockaded Woodpeckers—tree-dependent species that are easily impacted by intensive logging and the removal of trees. Clear cutting creates other, less obvious changes such as soil compaction, overall desiccation, and changes in soil chemistry and microfauna, which can be equally lethal for smaller, more cryptic species. Among the most vulnerable of these are the salamanders. In the southern Appalachian Mountains, the center of salamander diversity in the United States, it's estimated that logging has reduced the overall salamander population by 9%. The salamanders most vulnerable to logging impacts are probably the members of the family Plethodontidae, the largest salamander family, with 23 genera and well over 200 species, nearly half of which are native to the U.S.A. Having no lungs, these mostly small, slender amphibians breath through their delicate skin, which loses moisture quickly. Because of this, they venture abroad only at night and during rain, otherwise remaining ensconced under leaf litter or inside decaying wood. Despite their vulnerability, a mere seven plethodontid species appear on the USFWS Endangered Species List--three listed as threatened, four as endangered. In the western U.S., salamander diversity is centered in the Pacific Northwest, where the most common plethodontid is the Western Red-backed Salamander (Plethodon vehiculum), pictured above, which ranges from Vancouver Island south along the western slope of the Cascades, to southwestern Oregon. Just south of P. vehiculum's range, a small complex of plethodontid species straddles the Oregon/California state line. Considered a single species, P. elongatus, until recently, mitochondrial DNA analysis has provoked researchers to split it into three. In 2002 the Siskiyou Mt. Salamander, of the Applegate and Klamath River drainages, previously considered a subspecies, was given full specific status as P. stormi. California acted quickly to add P. stormi to its Endangered Species Act as a threatened species. Approximately 90% of the its known range occurs on Federal land, and the salamander's listing blocked several plans for timber harvest.
In May, 2005, the same researchers identified a population of salamanders near the confluence of the Klamath and Scott Rivers to be a unique species, the Scott Bar Salamander (P. asupak), pictured above. This time, the state's reaction was very different. The California Department of Fish & Game informed forestry officials and timber companies that since the new species is not on the state's ESA list, that logging could commence within its 28,000 hectare range. Three conservation groups sued the Department, and in a ruling this week, superior court judge Peter Busch stated that the Department of Fish & Game does not have the authority to strip the salamander's protection. The D.F.G. is also attempting to delist the Siskiyou Mt. Salamander. If this effort succeeds, it will be the first time in California history that a listed species lost state protection. It's a little surreal to watch such behavior from a state department entrusted with wildlife management. We can hope that last November's failure of California Congressman, chairman of the House Resources Committee, and sworn enemy of the Endangered Species Act Richard Pombo to win reelection marks the return of a wildly errant pendulum.
upper: WESTERN RED-BACKED SALAMANDER (2003) acrylic 4" x 10"
lower: Photograph of Plethodon asupak
(adult & juvenile) ©Tim Burkhardt

Thursday, January 18, 2007


Ron Blakey, a geologist at Northern Arizona University, has put together a very useful site, tracking the geography of North America over the last 550 million years. The site features 40 maps which were prepared with the core of North America (Laurentia) fixed. All other tectonic elements are shown moving against or splitting away from Laurentia, thus showing clearly accretionary and rifting events in North America's geologic history. The views were prepared by wrapping a rectangular outline map on a sphere and viewing the globe rotated to 35° N and 100° W. Various stratigraphic, tectonic, and sedimentologic data were added to the map. Topography was "cloned" from digital elevation maps of modern Earth from the USGS, NOAA, and other sources. Colors were adjusted to portray climate and vegetation for the given time and location. The geologic data were gathered from the references listed at the web

Monday, January 15, 2007


ART of the RAINFOREST, a travelling, ten-person exhibition of 65 paintings and sculptures representing tropical rainforest imagery, opens today at the Spartanburg County Museum of Art in Spartanburg, South Carolina, and will run through February 28th. The exhibition has visited four previous museums since its debut in 2005. After its Spartanburg run it will reside in the Exhibit Hall of the Detroit Zoo from March 20 through September 3, then on to the Mt. San Antonio College Art Gallery in Los Angeles, California from March 20 through May 15, 2008. Included in the show is my big triptych, Convoy through the Canopy (above), and eight other paintings of mine. Also included are the works of such fine artists as Richard Sloan, Anne Senechal Faust, Bart Walter, Gamini Ratnavira, Wes and Rachelle Siegrist, and Mark Kelso.
CONVOY THROUGH THE CANOPY (2000) acrylic triptych on illustration board 30" x 20"; 30" x 30"; 30" x 20"

Monday, January 08, 2007


My recent focus has been on painting, and postings have been infrequent for the past couple of months. I'm getting caught up, production-wise, and next week should see the beginning of a return to normal around here. In anticipation, here's a timely selection from the archives:

It's January 8th, and Isabel Allende is at her keypad. The author of The House of Spirits has written seventeen novels, and begun each one on this date. She will spend today ensconced in a locked room, pulling together the ideas for number seventeen that have tumbled around for God knows how long, in anticipation of this event.

Establishing such rituals comes naturally to most of us. Allende dismisses her January 8th tradition as superstition, but it's a clever device to enforce discipline upon her craft. Whatever their field, it's discipline rather than talent that distinguishes the really accomplished people in this world. If I had a dime for every gifted person I know who waits, fruitlessly, for a Muse to come a-knocking, I'd have, well...a lot of dimes. I never cared for the concept of the Greek Muses, anyway. I picture nine bespectacled bureaucrats, their hair pulled into severe buns. It's easier to relate to the Spanish persona of the Duende, that Lorca made famous: the rotten little gremlin, who, if not actually malevolent, is definitely a troublemaker.

Whatever specters visit the studio, they won't find a welcome home there without the presence of a work ethic. I only work at my best level while in a certain meditative state. Though I've never been physically south of Paraguay, while I painted Andean Condors & Patagonian Conures (above), my spirit swept across the mountains of Allende's Chilean homeland, feeling the cool alpine breeze, and hearing the sound of the condor preening his big, stiff feathers. Once I'm in this state, working hard is easy, but finding my way to that plane can be a chore. When things aren't going well in the studio, the smallest distraction serves to pull me from my work. “I wonder what I'd look like with my mustache waxed?”

This is when self-discipline is crucial, and “superstitions” like Allende's January 8th ritual are good things to have in the toolbox. The nature of inspiration is a mysterious thing, hence the many supernatural metaphors. Whatever's going on in Isabel Allende's office right now, though, it's safe to assume the Poltergeists are in there with her.
illustration: ANDEAN CONDOR & PATAGONIAN CONURES (1997) Acrylic 20" x 30"

Friday, January 05, 2007


Darren Naish has let the...er...squirrel out of the bag, so it's time for me to continue my armchair speculation about the Bornean Mystery Mammal (BMM). When the news was released at the end of 2005, some suggested the creature was a primate—in fact, I heard several authorities remark on its similarity to a lemur. The only qualifications a primate needs for lemurship, though, is a Madagascan pedigree, and the BMM falls short there. Neither of the Southeast Asian prosimians, tarsiers (Tarsius spp.) nor slow lorises (Nycticebus spp.), even vaguely approach the form of our friend. Other, even goofier, identities were suggested: a Bay Cat (Felis=Catopuma badia), and even a tree kangaroo (Dendrolagus sp.). Most of us assumed the animal was some kind of civet (family Viverridae). The commonly circulated photograph showed a crouching, chestnut mammal with a long, arching tail. What little of its face wasn't obscured by a leaf was washed out by its eyeshines. The most striking feature to me was the long hind limb, with its particularly meaty back of the knee, and plantigrade-looking posture. In the less-seen photo of the departing BMM, the hind limbs had a similar look that convinced me the animal was a civet, either one of the 7 species (not including linsangs and binturongs) known to occur on Borneo or something previously unknown on the island.

Most people I heard from agreed, in fact, a number of them seemed to think it was a Hose's Civet (Diplogale hosei), a Bornean endemic known only from 15 specimens. According to the description in Walker's Mammals of the World, D. hosei is endowed with a tail barely ½ of the snout-vent length, much shorter than the tail in the photos, and I rejected that notion outright (although an IUCN camera trap subject identified as that species sports a long tail--above).

At the time, I considered the Small-toothed Civet (Arctogalidia trivirgata) (top), and the Sulawesi Civet (Macrogalidia musschenbroekii) (lower) to be more likely candidates. Arctogalidia has the problem of a dark, grayish tail, and Macrogalidia is known only from Sulawesi, not to mention that its tail has light-colored bands (although the departing BMM photo could suggest similar markings).

Enter Erik Meijaard, an expert on Bornean mammals, and his colleagues Andrew C. Kitchener and Chris Smeenk, whose paper in Mammal Review (Vol. 36, No. 4, 318-324) proposes that the BMM was a flying squirrel, specifically Aeromys thomasi, a large and little known Bornean endemic. In their paper, the authors selected 17 known species that could possibly be mistaken for the BMM, and scored them on 14 morphological characteristics and one behavioral one, then compared the results against the BMM's score. A. thomasi came out on top, with 12 matches, compared to 4 for D. hosei. According to their table, the WWF photos were more likely to have depicted one of several squirrel species, a Maroon Leaf Monkey (Presbytis rubicunda), or a Housecat (Felis catta) than any known species of viverrid. Extra credit goes to the authors for including a pair of nice drawings by Ivan Noortwijk, that fill in the photographic shortcomings, to show how squirrelish the BMM might actually look (below).
After reading the paper, the squirrel hypothesis has a lot of appeal. Those meaty knees begin to look more like the little patagia that stretch from a flying squirrel's ankles to the base of his tail, and a piece of crumpled main patagium just might be peeking from behind the left elbow. I'm still bothered, though, by those hind legs, and a pelvis that just looks more viverrine to me than sciurine. I have never even seen a photograph of an Aeromys species (there are two), but as a boy I caught and kept two American flying squirrels (Glaucomys sabrinus), which are much smaller, and not particularly close relatives of the much more diverse Asian flying squirrels. That said, though, I've spent hours watching the American rodents negotiate on the ground, both walking and running, and the high-rumped posture in both BMM photos is extremely different.

As clever and interesting as the squirrel hypothesis is, I have a couple of minor disagreements with some of the supporting evidence the paper presents for it. The authors point out that the eyeshine of a flying squirrel is whiter than that of a civet, but photographs of eyeshines are usually quite washed out, and I regard them as poor evidence of true color. The tapeta of goatsuckers and crocodilians shine brilliant scarlet, but often appear white or yellow in photographs. The 15 characteristics that candidates were graded on did not seem particularly fair to me. Two of them, terrestrial habit and presence or absence of patagia, seem irrelevant. Much was made of the arched tail in the first photograph. The evidence that this posture is typical for the BMM is poor; a civet turning to its left could very well be captured in such a position, and the second photo shows no arching. The fact that a monkey and housecat scored far higher than a Small-toothed Civet illuminates the shortcomings of the process.

The authors mention a citation that describes another Southeast Asian flying squirrel, Iomys horsfieldi, on the ground with its tail “stretched out behind and arched sharply.” The arch of the BMM's tail is hardly sharp (note the exaggerated arch of the Noortwijk illustration and the far sharper arch of shown in the I. horsfieldi photo above).

I'm ultimately left feeling less sure of the creature's identity. Meijaard et al presented a good but inconclusive case, and though I'm unconvinced, I'm sure not going to say the creature isn't a squirrel. Rather than conclusively identifying the BMM, the authors confirmed the unreliability of photography, illustration, of our very eyes. The best lesson they provide is outlined in their conclusion: “We...recommend that wildlife photographers become more circumspect in announcing 'new' species, especially with media that are only too willing to widely publicize such news. The WWF has taken the right steps towards formal description of the 'new' mammal by attempting, so far unsuccessfully, to collect a specimen. This case highlights the importance of formal description based on type specimens and a review process.”
upper: Aeromys thomasi illustration by Karen Phillips (Field Guide to the Mammals of Borneo; WWF Malaysia)
second: Diplogale hosei photo from the IUCN
third: Arctogalidia trivirgata photo by Lim Boo Liat; Macrogalidia musschenbroeki photo by Christen Wemmer (Walker's Mammals of the World; Johns Hopkins)
fourth: BBM photos from the WWF; Aeromys thomasi illustrations by Ivan Noortwijk (Mammal Review)
lower: Iomys horsfieldi photo by El Rey Ardilla

Wednesday, January 03, 2007


Thirteen months ago, excited headlines heralded the discovery of a "new mammal species" whose image, both coming and going, had been captured by a camera trap set up by WWF biologists in central Borneo. From my own sampling of the general media, the consensus seemed to be that the photographs revealed either a hitherto undescribed species of primate or viverrid. I've had my own thoughts about the pictures, but haven't felt confident enough in my knowledge of mammalian anatomy to post them. Darren Naish has posted a fine synopsis of the conversation up till now on Tetrapod Zoology.

A new paper by a team of mammalogists who've forgotten far more about Bornean fauna and mammal morphology than I'll ever know believe that the WWF camera shutter was actually tripped by a member of a family most of us never considered. Their suggestion is clever and interesting, but despite my lack of expertise, or maybe because of it, I still have a bit of trouble swallowing it completely. I'll wait for Darren to post his conclusions before spoiling the surprise and weighing in myself.