Fishers Return to North Cascades

On an uncommonly sunny day in early February, I stood in a tract of old-growth forest not far from the Suiattle River to watch a missing mammal return to the North Cascades. With the return of the fisher, this area is one step closer to whole.

The fisher (Pekania pennanti) is one of the largest North American weasels. Adult females weigh four to six pounds and measure about 30 to 36 inches long, including tail, when fully grown. Males are about 20% larger, growing upwards of 13 pounds and nearly four feet long. Despite the name, fish are not a primary prey. Instead, fishers are wolverines of the forest. Highly arboreal, cylindrical in shape, and agile in motion, they are formidable predators of rodents, rabbits, hares, grouse, and other small to medium-sized animals.

fisher running to escape a box, people standing behind it

One of the first fishers to be released on February 6. The common name, fisher, is probably a modern English language corruption of “fitch,” a Middle English term for the pelt of the European polecat (Mustela putorius), also known as the common ferret. Not coincidentally, the colonial Dutch fisse and visse as well as the French fiche and fichet, all words for the polecat, sound quite similar to fisher. (NPS Photo)

Fishers were functionally extirpated from Washington by the mid 20th century due to habitat fragmentation and, especially, unregulated trapping. Surveys in the 1990s and early 2000s failed to find evidence of any viable fisher populations. As a first step to recover the species in the state, a coalition of public agencies, tribes, and private organizations released fishers in Olympic National Park from 2008-2010. This was followed by similar efforts in Gifford Pinchot National Forest and Mount Rainier National Park from 2015-2017. The North Cascades National Park Service Complex and Mount Baker-Snoqualmie National Forest began to host the fisher’s return last fall, which is how I found myself standing in the woods with about twenty other people on February 6.

Fishers prefer mature forests with a high canopy, relatively large diameter trees, and an abundance of downed trees. Dead standing trees are particularly important to fishers, as they den exclusively in tree cavities. The release site for the fishers this day seemed particularly well suited to their needs.

forest and stream

Fortunately and conveniently, healthy populations of fishers remain in British Columbia and Alberta and they serve as the source for the restoration effort. Fishers from western Canada are also genetically similar to those that used to inhabit Washington. Canadian trappers were paid to capture live, healthy animals. The Calgary Zoo temporarily housed the fishers while veterinarians evaluated their health and surgically implanted tiny radio transmitters to assist biologists in tracking them.

Twelve hours before release, these particular animals were still in Calgary. At 1 a.m., the fishers were flown to Abbotsford, British Columbia where they were picked up by biologists and driven into Washington. By early afternoon, a gang of biologists and a few interested souls like me were unloading the cargo and carrying the fishers a short distance to the release site.

Fisher release, Buck Creek Campground, Mount Baker-Snoqualmie National Forest_02062019_4

Fishers were transported in specially designed crates. Two fishers, separated by a partition, are in each crate.

view through screened hole of fisher in a box

A fisher peeks through a window toward the outside world.

people carrying wooden crates on forested path

Our group formed a semi-circle around the crates to watch the release. Conversations quieted to a whisper or died in anticipation as the crates were opened one at a time. To coax them out, a screened vent was opened at the top and a volunteer blew a puff of air into the container. I’m unsure if this was as annoying as someone blowing air into my ear, but the trick worked. The fishers shot out like a flash and bolted into the forest.

Six fishers were released that day bringing the total number currently released in the area to 24. The release efforts will continue until about 80 fishers are reintroduced to the area. Biologists will track, monitor, and study the animals to assess survival rates, identify where they go after release and where they establish home ranges, the types of foods they eat, and the diseases and parasites they suffer from.

The effort has a high chance of success. Reintroductions, however, are rarely so simple. Fishers, although not well known among the general public, are relatively non-controversial animals. They don’t evoke the same emotional reactions in people as grizzly bears or wolves, for example.

More than that, however, the forested habitats along the core and margins of the North Cascades are largely intact. Land managers needn’t take extreme, expensive, time-consuming measures to restore the ecosystem to a point where it could support fishers again. It could always support them. We just didn’t allow fishers to survive here.

Because prior generations had the foresight to protect places like North Cascades National Park and Glacier Peak Wilderness, we have the opportunity to restore fishers to land they once knew as home. Situations like these are becoming increasingly uncommon. People have fundamentally altered so much of the Earth to preclude the reintroduction of many extirpated species into their historic ranges. (There’s no substantial habitat available for bison in Iowa, for example.)

view of old growth forest with large coniferous trees

Potential future fisher habitat along Stetattle Creek in North Cascades National Park.

As humanity’s footprint grows, undeveloped landscapes are increasingly valuable, not for the resources we can exploit within them (including supposedly non-consumptive uses like solitude), but as repositories of biodiversity and ecosystem health. To adapt an idea from Thoreau, future generations, I believe, will measure our legacy not by what we invented and consumed, not by our material wealth, but by what we can afford to let alone.

I’ll probably never see any of these fishers ever again. Even if the population increases to hundreds of individuals, they’ll remain reclusive neighbors. If I’m lucky, I may find a track in fresh snow or its scat on a log. But even that doesn’t matter. I’ll know they are there and I’ll know the landscape is healthier because of it. The return of the fisher represents, at least in one small way, the success of our ability to let one place—North Cascades—alone.

Happy Birthday Bear

Across much of North America, tucked within isolated dens, a new generation of bears is beginning their lives.

Mother bears spent much of the last year preparing for this event. Although the timing varies among species and individuals, North America’s bears mate in late spring and early summer. The fertilized eggs, however, do not immediately implant in the uterus, undergoing only a few cell divisions before they enter a state of arrested development. During this process of delayed implantation, the female goes about her business while embryos remain in suspended animation. Implantation and fetal growth renew only close to the time she enters her winter den. Afterward, bear fetuses gestate for 6 – 8 weeks.

The gestation time is remarkably short for such a large mammal, and it produces especially tiny and helpless cubs. Brown bear cubs, for example, weigh a scant pound and measure only 8 – 9 inches long at birth, about the size of a beagle puppy. They are also born blind, lightly furred, and nearly immobile. Their ears are closed and their muzzles are short with a round, toothless mouth. Newborn cubs are so underdeveloped and small that they cannot maintain their own body heat in the den and must remain in contact with their mother to stay warm. About the only thing they can do is scream, which, not unlike human newborns, they employ frequently to gain their mother’s attention. It’s hard to imagine large adult bears so helpless, but they all start life this way.

Three small cubs held in a person's hands.

Newborn black bear cubs. U.S. Fish and Wildlife Service photo.

The small size of newborn cubs is surprising for animals that weigh several hundred pounds when fully grown. Generally, larger mammal species have longer gestation periods and give birth to larger offspring than smaller mammal species. African elephant calves gestate for nearly two years and are born bigger than elk calves; elk calves gestate for about eight months and are born bigger than deer fawns; deer fawns gestate for seven months and are born bigger than fox kits; etc. But, bears break the rule by a considerable margin. Bears give birth to the smallest offspring in comparison to adult female body size of any mammal.

Cubs are only 1/200th the size of even the smallest reproducing female grizzlies and commonly 1/500th or less for large adult brown and polar bears. In contrast, newborn human babies are an order of magnitude larger than bear cubs. A 10 pound child born from a 150 pound woman is 1/15th the size of its mother (yeah, I know that’s a big baby but the math was easy). Additionally, offspring born to large mammals are generally precocial, i.e. they are at least somewhat and sometimes highly mobile soon after birth. Bear cubs, however, are more akin to helpless hatchling birds or pinky mice. There is no parallel among placental mammals—only marsupials give birth to offspring as undersized as bears.

But why are bear cubs born purposefully premature? Why not just have a longer gestation time and birth larger, more independent cubs? The short gestation period and the relatively small size of bear cubs at birth both appear to be an adaptation to maximize the use of fat.

Bears are the only mammals that give birth while hibernating, a time when they do not eat, drink, urinate, or defecate. Survival during this time is dependent on stored body fat, but the paradigm poses a problem for expectant female bears. A developing mammal fetus cannot metabolize free-fatty acids, perhaps because these substances do not cross the placenta as readily as sugars and protein. So, as long as a bear tries to sustain fetal growth through her placenta, she needs to draw energy from her own body protein. Fetuses also produce bodily waste, which is transferred to the mother and adds to her physiological challenges. To cope, bears evolved an alternative strategy, one that allows her to give birth while hibernating, support the continued growth of cubs, and keep the family safe.

Unlike in the womb, baby mammals can metabolize fat shortly after birth and milk is the vector to deliver it. Bear milk is a particularly rich and nourishing substance. Brown bear milk, for example, is about 22% fat by volume. Polar bear milk is even richer, a whipping cream composed of over 30% fat. By shortening the gestation period, mother bears trade placental nourishment (mostly protein and sugar) for mammary nourishment (mostly fat) and tap into the one resource they have in abundance.

fat brown bear exiting water

Female bears utilize their fat reserves to support the growth and nourishment of their cubs.

On a diet of fatty milk, a brown bear cub can gain about a 1/5 of a pound of body mass per day, weighing about 5 pounds when one month old and 15 – 25 pounds by 90 days. Not coincidentally, this is about big as they would be if gestation was of an “expected” length like other placental mammals. The den, therefore, becomes a surrogate womb, protecting the family during the most vulnerable time in their lives.

Two polar bear cubs standing at the entrance to a snow den.

Polar bears play at the entrance to their mother’s den. These cubs are probably several weeks old. U.S. Fish and Wildlife Service photo.

Bears face many obstacles to survive and reproduce, not the least of which is winter famine. Hibernation provides bears with the ability to outwit winter by surviving on accumulated fat, but during this time a female bear must support the growth of her cubs with nothing more than the energy stored in her body. Given the challenges posed by gestation, hibernation, and winter famine, the birth of a bear represents a remarkable and unparalleled feat of mammalian adaptation.

So, happy birthday brown bear.

A Mountain Lion Prowls the Neighborhood

There’s a place along the Skagit River where I like to wander. Upstream and downstream, the river is lined with rural home sites, but in between there’s a small pocket of undeveloped land where relatively few people go. Compared to the wild lands surrounding nearby Mount Baker and the North Cascades, it’s a small area and nothing close to what most people would consider wilderness. A regenerating clear cut sits on a terrace above the water. Below it, the river flows through a shallow S-curve and a swampy area occupies the annual floodplain. Filled with a willow thicket, it’s a good place to hide, for me as well as many other animals.

I’ve made it a habit to explore the animal trails leading in, out, and through the floodplain. In the spring, when the water table is higher, Pacific tree frogs spawn in ephemeral pools. In fall, a black bear visits the riverbank to scavenge spawned-out salmon. All year, elk use it to move between pasture. I frequently see sign left by coyotes, and if I look hard enough I might be able to find the tracks and scat of bobcats. While I rarely see the live animals, exploring their haunts helps keep me connected to the other creatures that I share this place with. I have a spot within this area where I like to sit and listen, but sometimes the most interesting observations happen upon my approach and exit into this little pocket of wilder land.

Following an elk-maintained path down to the riverbank, I exited the forest onto a muddy side-channel, now mostly dry after a long, arid summer. The exposed mud and sand of late summer offer some of the best tracking opportunities of the year. I slowed my pace, eager to see which animals had moved through the area recently. In the semi-firm mud, I stumbled upon a set of feline tracks. The tracks were large, as wide as the palm of my hand with four clear toe prints. There were no claw marks and the sizable metacarpal pads were distinctively three-lobed at the base. These belonged to a mountain lion.mountain lion tracks in mud. Notebook is approximately 7 inches wide.mountain lion track in mud. track point towards right. Notebook is approximately 7 inches wide.mountain lion tracks in sand. tracks point towards notebook at bottom of photo. Notebook is approximately 7 inches wide.Curious to know more about its travels here, I followed the tracks along the edge of the river. The cougar followed the same general path I would have to move upstream; it stuck to the mud and driftwood on the edge of the willows. From the additional tracks I was able to find, the cougar continued along the riverbank for another hundred yards before I lost the trail in the adjacent thicket.

Based on my completely unscientific survey of mammal sign in the surrounding few acres, elk seemed to be the most abundant large animal here. They left many sets of tracks that moved perpendicularly from the river and into the deep cover provided by the willows. Was the lion stalking potential prey, or was it simply wandering through? Could a kill site be nearby? My imagination ran with the possibilities, but the dense vegetation would effectively hide any further evidence of the lion’s travels—unless I was lucky enough to stumble upon more sign.

Discounting that possibility as too unlikely, I left the river by following a narrow elk trail lined with salmonberry. The trail led, in a convoluted manner, to my sit spot where I sat for while to jot a few written notes and listen to the forest.

forest scene with taller trees in background and many small shrubs in foreground

To head home, I took a different yet familiar route along more elk trails. By this time, I wasn’t expecting to find any more sign of cougars (the duff was too well compacted and dry to hold their paw prints), but when I reached a fork in the trail I found evidence that at least one cougar had visited the area several times. Under low hanging branches of western red-cedar were four large scrapes. Each scrape was oblong and about a foot in length. Each had a small pile of debris at the base and three were accompanied by scat.

photo of mountain lion scrape in forest litter. notebook at bottom left is about 7 inches wide.photo of mountain lion scrape in forest litter. notebook at bottom left is about 7 inches wide.

Mountain lions are reported to urinate when they make scrapes, but I couldn’t detect any strong urine odor despite kneeling down for a better waft. Evidently, the cougar had been here several times, but not that day and perhaps not even the past week. It looked to be eating well when it was here though. One pile of scat was sizable and reflective of a diet heavy with meat.

I found no other mountain lion sign that day, but the scrapes and tracks caused my mind to again race with the possibilities of its life here. Did it make a kill nearby? Or, was it merely using the heavy cover as a secure place to rest between meals? I left with more questions than answers. This mountain lion’s story might be missing some pages, but sometimes the finer details of a good tale are best left to the imagination.

The Worst Place in the World for a Mine

“This is the jewel in the crown of America’s fisheries resources – these salmon. If you don’t think this is worth saving, what is? To me, if you don’t draw a line in the sand here, there’s none to be drawn anywhere.”

Thomas Quinn
Professor, University of Washington and author of The Behavior and Ecology of Pacific Salmon and Trout

After more than a decade of controversy, Pebble Mine is inching closer to reality, and from the perspective of salmon, we couldn’t choose a worse place for an open pit mine.

red salmon swimming in shallow water

If you’re unfamiliar with Bristol Bay, its salmon, or Pebble Mine, please watch this 2012 overview on the Pebble Mine controversy, keeping in mind the mine’s currently proposed size and mineral processing plans are different than those outlined in the video.

Pebble Mine is a proposed open-pit copper, gold, and molybdenum mine at the headwaters of some of the last intact and most productive salmon habitat on Earth. Before any development of the mine can begin however, it must be permitted, and before it can be permitted, it must undergo an extensive environmental review. This is where we stand currently: the environmental impact statement (EIS) process for Pebble Mine has begun.

An EIS goes through several stages before a “record of decision” is finalized. Right now, the Pebble EIS is only at the scoping level. If you’re unfamiliar with the EIS process, public scoping is basically a brainstorming step. It’s the public’s opportunity to help define the breadth of the EIS to the lead agency, which in this case is the Army Corps of Engineers. (Read more about the scoping process.) During public scoping, if people don’t express concerns for the ecosystem-wide impacts of Pebble Mine and its infrastructure then the Corps’ EIS will not address them. Therefore, we must comment during the scoping period and demand that the alternatives in the EIS address the mine’s full environmental impact—which will sprawl across southwest Alaska and threaten the last great sockeye salmon run in North America.

The Bristol Bay area is exceptionally special and unique. Its landscape remains largely undeveloped and un-engineered. The major factors that decimated salmon elsewhere—habitat loss, dams, and pollution—are absent and salmon runs reach tens of millions of fish annually. Bristol Bay is where we can imagine the richness of fish that used to flood into the Columbia River or New England. It remains home to one of the most valuable and sustainable fisheries on Earth, one of the few remaining places where the full potential of the ecosystem is realized.

salmon jumping at waterfall

Salmon fishing boats in Naknek

Salmon fishing boats sit idle on a late winter day in Naknek, Alaska. The 2017 Bristol Bay salmon harvest was worth $670 million.

The Pebble EIS must address the mine’s potential, worst-case scenario effects on Bristol Bay’s salmon. A failure to contain the mine’s toxic tailings and wastewater would directly impact two of Earth’s most productive salmon producing watersheds. (The Kvichak River watershed, where part of the mine will be located, is home to the single largest salmon run in the world.) It must address potential groundwater exchange in the abandoned open pit, and whether the mining company can eliminate the risk of acid mine drainage. It must address whether the embankments for tailings ponds can withstand high magnitude earthquakes. It must address whether it’s even appropriate to build a mine whose wastewater will need to be treated indefinitely. It also must critically evaluate the mine’s supporting infrastructure, as it will potentially disrupt the world’s largest seasonal congregation of brown bears.

Map outlining Nushagak and Kvichak watersheds. Red star marks location of Pebble Mine.

Pebble Mine will straddle the divide between the Nushagak and Kvichak watersheds, two of Bristol Bay’s riches salmon producing areas.

By law, the EIS process must identify the least environmentally damaging practicable alternative. Common sense implies the least damaging alternative in this case is no mine at all, but the National Environmental Policy Act does not require agencies implement it. If we don’t demand the Corps critically evaluate the myriad impacts from the mine, then the Corps will merely focus on holes in the ground, “alternatives” of natural gas versus diesel to power the mine, how wide the service roads will be, and the size of the ports. The scope of the EIS will be so narrow to be useless for the protection of salmon. (For an idea of what this might be, look no further than the Donlin Mine Final EIS, whose purpose and need is: “produce gold from ore reserves from the Donlin deposit using mining processes, infrastructure, logistics, and energy supplies that are economical and feasible for application in remote western Alaska. The applicant’s stated need for the project is to provide economic benefits to Donlin Gold, Calista, and TKC shareholders; and to produce gold to meet worldwide demand.”)

I recognize a sad irony—or hypocrisy, if you prefer—of using a computer, which contains gold and copper, to type this post. I understand there’s a hole in the Earth, perhaps filled now with toxic water, where the metals in my machine were once trapped in rock. If you, like me, think Pebble Mine is irresponsible, then voice your opposition not only through the EIS process and with your votes at the ballot box (politicians who support Pebble Mine will not receive my vote), but also by reducing your consumption of products that use gold and copper. We, as consumers, need to say enough is enough. Our addiction to ever-higher levels of consumption brought us here. It’s not really sufficient to say “I’m opposed to Pebble Mine” then go out and buy the newest iPhone even though your old phone works just fine.

Everything we use, everything we make, has a cost. We’re at a point in history when surging human population growth and mass consumption are pushing ecosystems and species to their breaking point, creating an ecologically impoverished planet. In New England, wild Atlantic salmon are nearly extinct, and on the U.S. west coast only a tiny fraction of Pacific salmon return compared to historic levels. Don’t kid yourself: This sad story can repeat itself in Alaska.

We lose salmon one impassible culvert, one dam, one levee, one mine at a time, leaving us to suddenly wonder, where did all the fish go? In Bristol Bay we have a chance, maybe our last chance, to save large runs of wild salmon. If the mine is built and its proposed safeguards fail, we risk losing a significant portion one of the world’s last great sustainable fisheries. Future generations won’t be celebrating our decision if we develop this mine. They’ll criticize us for not learning from the mistakes of the past. Are we really willing to let hyper-consumerism and the promise of short-term profits potentially destroy the last great salmon run?

It looks like we’re on track to do so, unless enough people step up and say no.

Through June 29, 2018, you can submit scoping comments on the Pebble Mine EIS. I’ll share my scoping comments in a forthcoming post when they are finished.

Update May 23, 2018: My scoping comments can be found here.

Hibernation Hangover

In Glacier National Park, Montana, a black bear has emerged from hibernation, but hasn’t left his tree cavity den.

According to the park website, this bear was first seen on March 23. Since then, the black bear, who is male, has mostly rested in the tree cavity. After a long winter of hibernation, you might assume a bear would be eager to get moving and find something to eat, but bears often don’t leave their denning site for days, sometimes weeks, after they emerge in the spring.

A bear fresh out of the den isn’t the same bear it will be in May. Immediately after emerging from their dens, bears are active but neither hungry nor particularly thirsty. In one of the first studies on the physiology of hibernating bears, researchers found captive bears ignored food and water for up to two weeks and some bears didn’t begin to eat and drink normally for three weeks after they emerged from their dens. One grizzly bear didn’t even urinate for two days after it emerged. (In contrast, during another study a black bear in the fall urinated copiously, producing eight to sixteen liters of urine per day.)

This annual life stage of springtime bears has been described as “walking hibernation.” Compared to summer and, especially, early fall, bears in walking hibernation are hypophagic. They actively ignore food and drink little water while still surviving on body fat. During walking hibernation, bears experience an internal transition from full hibernation to a more active physiology. Research on brown bears in Sweden, which I wrote about previously, has found the body temperature and metabolic rate of brown bears doesn’t stabilize until 10 and 15 days, respectively, after den emergence and their heart rate doesn’t stabilize for another month.

Graph that shows the timing of several variables affecting the start and end of hibernation in bears.

These graphs chart the relationship between physiological parameters of brown bears in Sweden. Den entry (left column) and exit (right column) are indicated by time zero (the green vertical line) to determine the sequence of physiological events. SDANN is the standard deviation of heart rate variability over five minute intervals. It was used a proxy measure of metabolic activity. A red line denotes when a variable was decreasing, while a blue line indicates when a variable was increasing, with the number of days from the entry/exit indicated. From Drivers of Hibernation in the Brown Bear and reposted under the Creative Commons Attribution 4.0
International License.

bear feet sticking out of hole in tree trunk

The transition from hibernation to fully active includes lots of resting. Screen shots from the Glacier National Park bear den live stream.

black bear in tree cavity

Possibly because their metabolism and heart rate remain somewhat low, many bears seem to loathe leave their dens, at least right away. So, it’s not uncommon for bears to remain near their denning site while their bodies transition back to more active levels.

The bear at Glacier will leave its tree cavity den relatively soon. His hunger will grow as his metabolism returns to active levels. His libido will increase too, and he’ll begin to prowl the land for females in estrous (the mating season for black and grizzly bears peaks in late spring). Compared to other stages in their annual cycle, less is known about the first few weeks of life for bears after they emergence from hibernation. It is rare for us to witness a bear’s life at this time. With webcams and other digital tools like GPS collars, we’re gaining a greater depth of knowledge about many wild animals. Glacier’s webcam provides a rare opportunity to observe a bear shortly after it has emerged from hibernation. Like most bears right now, it remains in a bit of a hibernative hangover.

The Difference Between Brown and Grizzly Bears

For my book on Brooks River’s bears and salmon, I find myself digging deep into natural history and ecology of brown bears. Sometimes I uncover research that challenges my long held assumptions. Take the difference between brown and grizzly bears, for example; something I often said was mostly based on geography and diet. As I wrote for Katmai’s website:

All grizzly bears are brown bears , but not all brown bears are grizzly bears. Grizzly bears and brown bears are the same species (Ursus arctos), but grizzly bears are currently considered to be a separate subspecies (U. a. horribilis). Due to a few morphological differences, Kodiak bears are also considered to be a distinct subspecies of brown bear (U. a. middendorffi), but are very similar to Katmai’s brown bears in diet and habits.

Even though grizzlies are considered to be a subspecies of brown bear, the difference between a grizzly bear and a brown bear is fairly arbitrary. In North America, brown bears are generally considered to be those of the species that have access to coastal food resources like salmon. Grizzly bears live further inland and typically do not have access to marine-derived food resources.

These geographic and dietary distinctions seem simple enough. However, there is little scientific evidence to support it. Both brown bears and grizzly bears exist, but the differences between them aren’t what I had long assumed.

bear grazing on vegetation with travertine and forest in background

A grizzly bear grazes on springtime vegetation near Old Faithful in Yellowstone National Park.

bear in water

A brown bear at Brooks Falls in Katmai National Park. (NPS Photo)

Although North American brown, grizzly, and Kodiak bears belong to the same species, Ursus arctos, bear taxonomy underwent many revisions before scientists reached this conclusion. In the nineteenth and twentieth centuries, taxonomists frequently lumped and split brown/grizzly bears into many different species and subspecies. The separation peaked in 1918 with the publication of C. Hart Merriam’s Review of the Grizzly and Big Brown Bears of North America in which Merriam proposed around 80 (not a typo) species and subspecies of North American brown bears. Taxonomists like Merriam relied on morphological characteristics that could be seen or observed to classify living and extinct organisms. Warm-blooded animals that have hair, breathe air, and produce milk for their offspring are mammals, but warm-blooded and air-breathing animals that lay eggs, have feathers and toothless beaks are birds. These are greatly simplified examples, I realize, and such tidy and clear distinctions aren’t necessarily common in nature. They often become more difficult to resolve at the genetic and species level, especially in cases of hybridization or when taxonomic distinctiveness is based on subtle physical differences.

Merriam’s nuanced classifications of brown and grizzly bears were based on differences in skull morphology and dentition, characteristics he examined painstaking detail. Among taxonomists, Merriam was a splitter. On southeast Alaska’s Admiralty Island alone, he classified five distinct species . In the Katmai region, Merriam described two species, Ursus gyas for the Alaska Peninsula and Ursus middendorffi for Kodiak Island , as well as others for bears living in the Cook Inlet area and on the Kenai Peninsula.

If you think his classifications of brown/grizzly bears was a little over the top, you’re not alone. Merriam foreshadowed opposition to his conclusions when he wrote in his Review, “The number of species here given will appear to many as preposterous . To all such I extend a cordial invitation to . . . see for themselves.” And they did. Most of the species or subspecies described by Merriam were later regarded as local variations or individual variants. While all of Merriam’s species have since been lumped together as U. arctos, in the mid 1980s as many as nine extant or extinct subspecies of U. arctos were recognized in North America , but the only names for North American brown bear subspecies in still widely used are U. a. horribilis, the grizzly bear, and U. a. middendorffi, the Kodiak bear. Recently, however, even these classifications have come under question.

In hindsight, it’s easy to scoff at Merriam’s conclusions. Could there really be dozens of brown bear species in North America? Within the methodologies and knowledge of his era, his results aren’t that far fetched. Little was known about the behavior, growth rates, ecology, and population dynamics of North American bears in the nineteenth and early twentieth centuries. Given access to the same tools and information as modern taxonomists, Merriam may have discovered grizzly and brown bears can’t be so easily divided by differences in skull and tooth shape.

Ursus arctos is one of the most widely distributed mammal species on Earth. Historically, brown bears were found from the British Isles south to North Africa and east across northern and central Asia to Alaska and most of western and central North America. Two to three million years ago, they split from a common ancestor shared with black bears . The oldest brown bear fossils are from China and date to about 500,000 years ago. By 250,000 years ago, they spread to Europe. During the last 100,000 years of the Pleistocene, bears immigrated and emigrated across much of the northern hemisphere as climate and habitat dictated. When continental ice sheets advanced, available habitat shrunk and bears became isolated into separate populations. When the ice receded, bears dispersed into the new territory. Beginning around 70,000 years ago, the first brown bears moved into North America. While we know when and where bears lived and live from fossils and historical records, this doesn’t necessarily deduce the genetic relatedness of modern populations.

Phylogeography is a branch of phylogeny, the evolution of an organism or group of related species or populations. As such, phylogeography traces the distribution of genetic variation through time and space. In this regard, mitochondrial DNA (mtDNA) is especially useful to track female ancestry. MtDNA  resides in the mitochondrion, a cell’s powerhouse, and is inherited from the mother only, unlike nuclear DNA which is a recombination of genes from both parents. According to mtDNA analysis, there is no divide between brown and grizzly bears based on an animal’s relationship to the coast or marine food sources, nor does it support the status of U. a. horribilis or U. a. middendorffi or any other historical subspecies in North America. The only historic classification that holds is at the species level—Ursus arctos. Instead, matrilineal ancestry suggests brown bears in North America fall into three main clades.

  • Mainland Alaska, Kodiak Archipelago, and northwest Canada.
  • ABC Islands (Admiralty, Baranof, and Chichagof) in southeast Alaska.
  • Southwestern Canada (Alberta, British Columbia) and the lower 48 States.

Clades are groups of organisms evolved from a common ancestor and consequently share a genetic relationship. The three North American clades, as well as others in Europe and Asia, are believed to be descended from brown bears living in isolated populations in Asia during the late Pleistocene . Since then, the mtDNA has remained geographically separated due to the tendency of female brown bears to be homebodies. Female brown bears are philopatric. They tend to remain near or have partly overlapping home ranges with their mother and do not rapidly invade areas already occupied by other brown bears . This can prevent or at least greatly slow mtDNA from mixing into other bear populations, even long after significant barriers like ice sheets have disappeared.

screen capture of Earth with clades of bears outlined.

Approximate range of brown bear clades in North America based on mtDNA. Different clades are represented by horizontal and vertical lines. The solid red circle marks the location of brown bears on the ABC islands.

Bears on the ABC Islands are the most genetically distinct of all Ursus arctos. Their mtDNA aligns them more closely to polar bears than to other brown bears , a genetic uniqueness most likely resulting from interbreeding with a small number of isolated polar bears at the end of the last ice age. Since then, female brown bears on the islands have not spread their polar bear genes to the mainland. Bears in British Columbia, Alberta, and into the lower 48 represent another lineage who arrived in Alaska around the same time as the ancestors of the ABC bears. During a warm interglacial period, some of these bears moved south into the mid continent before the ice advanced again and sealed them off from their brethren to the north.

All other brown bears in northwest Canada and Alaska, including those on Kodiak, belong to a clade that dispersed from Asia in two separate waves. Those in northwest Canada arrived first, perhaps as early as 33,000 years ago. Bears now occupying mainland Alaska represent the last pulse of ursine migrants onto the continent, arriving just before rising sea levels flooded the Bering Strait and closed the land bridge between Asia and North America. Excluding the ABC islands, all Alaskan brown bears belong to this pedigree, which stretches from northwestern Canada and Alaska west across Russia and into Europe and includes most of the world’s brown bears.

The results from mtDNA only convey information about the maternal line, however. MtDNA cannot trace genes spread exclusively by male brown bears, so it underrepresents the role of males in gene flow. Male brown bears have larger home ranges and disperse away from their mother’s home range more readily than females, especially during their first few years of independence. Males do carry one important bit of DNA that females don’t—the Y chromosome. Like mtDNA, it is only inherited from one parent, but unlike mtDNA it can only be passed from father to son, making the Y chromosome an important marker to trace paternal gene flow and diversity.

While mtDNA shows particularly strong clade differentiation  across the entire range of Ursus arctos, geographic variation in the Y chromosome of brown bears is much shallower . According to analysis of the Y chromosome, no deep genetic or geographical divergences could be found from bears in Eurasia or North America. Brown bears on the ABC islands and mainland Alaska, for example, share closely related haplotypes (a group of genes inherited from a single parent ) found in the Y chromosome. Even brown bears from populations as separate as Norway and the ABC islands have been reported to carry highly similar Y chromosomes . Male genes, therefore, flow across clades.

infographic showing hypothetical inheritance of mitochondrial DNA and Y-chromosome through three generations of bears.

Within mammals, mitochondrial DNA can only be inherited through the maternal line. The Y chromosome is only passed from father to son. MtDNA tends to stay within genetically related clades because female bears are philopatric. Male bears, due to their inclination to disperse farther and have larger home ranges than females, can spread Y chromosomes over bigger areas. Unlike nuclear DNA, neither mtDNA nor the Y chromosome are a mix of maternal and paternal genes.

This isn’t to imply male bears from the Yukon immigrate to Europe or vice versa, just that males are more apt to wander and set up home ranges well away from their mother. If female brown bears, due to their philopatry, differentiate a population’s genetics over time, then male bears homogenize it. In other words, female brown bears like to stay in familiar terrain, but males often spread their seed far and wide.

With evidence of geographically isolated clades through mtDNA but not in the Y chromosome—can we still divide brown bears into biologically significant units? Even though genetic research adds another dimension to our understanding of wildlife, morphology remains an important way to differentiate species, and subspecies don’t necessarily need to be from separate or unique ancestry to be worth protecting. Grizzly and brown bears still exist, just not along a clean geographic and dietary divide. Where we draw the line is less important than the overall conservation of bears. Populations of brown bears—whether they are from Katmai, Kodiak, or Yellowstone—remain ecologically and culturally special no matter their genetic distinctiveness. Bears in Yellowstone are geographically and (at least currently) genetically separated from other “grizzlies.” Kodiak bears aren’t genetically distinct enough to justify them as a separate clade even though they have been isolated from mainland bears for approximately 12,000 years. Hypothetically speaking, if bears are extirpated from Kodiak or Yellowstone then they won’t be coming back and a valuable repository of genetic diversity will be lost forever.

The line between a brown bear and a grizzly, as I used to define it, was always tenuous at best. (Should grizzlies in interior Washington, British Columbia, and Idaho—who may have fed on salmon before runs in the Columbia and Snake watersheds collapsed—be considered brown bears?) Now through DNA analysis we know Ursus arctos cannot be so arbitrarily split based on their geographical closeness to the ocean. It’s still ok to say grizzly, Kodiak, or brown bear—the names can still be incredibly powerful and useful—but maybe the only truly accurate name for them is Ursus arctos.

References:

Bidon, T. , et al. Brown and polar bear Y chromosomes reveal extensive male-biased gene flow within brother lineages. Mol. Biol. Evol. 2014. 31(6): 1353-1363.

Davidson, J., et al. Late-Quaternary biogeographic scenarios for the brown bear (Ursus arctos), a wild mammal model species. Quaternary Science Reviews. 2011. 30:418-430.

Rausch, R. L. Geographic Variation in size in North American brown bears, Ursus arctos L., as indicated by condylobasal length. Canadian Journal of Zoology. 1963. 41(1): 33-45.

Schwartz, C.C. et al. “Grizzly Bear,” in Wild Mammals of North America: Biology, Management, and Conservation. 2nd Edition. Editors Feldhamer, George A., Bruce C. Thompson, and Joseph A. Chapman. John Hopkins University Press. 2003.

Talbot S. L., et al. Genetic characterization of brown bears on the Kodiak Archipelago. Final Report to Kodiak National Wildife Refuge, U.S. Fish and Wildlife Service. 2006.

Waits L. P., et al. “Genetics of the bears of the world.” In Bears: Status Survey and Conservation Action Plan. Compiled by Christopher Servheen, Stephen Herrero, and Bernard Peyton. IUCN/SSC. 1999.

Waits, L. P., et al. Mitochondrial DNA Phylogeography of the North American Brown Bear and Implications for Conservation. Conservation Biology. 1998. 12(2): 408-417.

 

To Change or Not To Change: A National Park Question

Last year, Isle Royale National Park released a draft plan to determine whether and how to stabilize the park’s wolf population. After evaluating the merits of several alternatives, weeding through public feedback, and with only two wolves remaining, the park has decided to introduce 20-30 wolves over a three-year period. In the park’s decision, managers have affirmed their belief that wolves on Isle Royale are an irreplaceable part of the ecosystem, and their loss is unacceptable.

Parks are being increasingly managed for change, but the myth of national parks as static vignettes of primitive America remains pervasive. As I wrote on this issue last year, parks are not pure. We live in an era of unprecedented change, and situations like Isle Royale’s will only become more common.

The National Park Service has made strides toward acknowledging that parks will change, but it’s time to put a greater effort into planning for it. To help the public better understand the dynamic nature of national parks and their significance—what we’re willing to save and what we’re willing to let go—there should be an effort across the NPS to identify at-risk resources and decide whether to protect them. Resources to protect would be species, habitats, and processes that if lost would impair the significance of the park or reduce biodiversity. This could help guide current and future management of parks, leading the NPS to implement preventative or prescriptive actions to stave off unacceptable impairment instead of waiting until it’s nearly too late.

In areas with endemic or endangered species—such as Hawaii Volcanoes, Haleakala, and Channel Islands—it may be most appropriate to manage against change to mitigate the risk of losing unique habitats or species to extinction.

In other areas where forest compositions will shift, it may be more appropriate to let change happen as long as native biodiversity is protected.

view of tundra and shrubs with mountains and lake in background

In Katmai National Park, shrubs and trees now grow at higher elevations compared to 100 years ago.

view of mountain scenery with craggy peaks and snowfields.

Should this view be protected or should tree be allowed to encroach on the scene? At North Cascades National Park, tree line is expected to rise in elevation which may threaten views like this one near Cascade Pass. Forests in this park, especially at low elevations, are also projected to burn more frequently under a warmer climate.

Importantly, this planning effort could help the public better understand decisions like Isle Royale’s, which seems inconsistent and arbitrary to many people who commented on the plan.

Biologists predict wolves will be extirpated from Isle Royale within a few years without direct intervention, but why intervene on the behalf of wolves at all? Wolves, as a species, don’t need Isle Royale to survive. As the NPS reasons, it’s less for them, and more for the park. Without wolves climate change would have a greater influence on the archipelago. Plant communities would shift dramatically under heavy browsing pressure from moose, causing a cascade of effects and perhaps, according the park’s Final Environmental Impact Statement, become less resilient.

“Under alternative A, increased [moose browsing] is probable and combined with climate change effects, it is likely that the rate of vegetation changes would be exacerbated and potentially accelerated. Additionally, it is expected that the resiliency of current wildlife populations to change would be reduced and contribute to more rapid population swings. Under alternative B [the preferred alternative] and C, it is expected that the project [sic] warming trends influences [sic] on the island would be less likely to be compounded by herbivory and its associated impacts.” (Pg. V)

Scenarios like Isle Royale’s will only become more common as we continue to fragment habitat, introduce invasive species, and change the climate. Not that I want it to be this way. Ideally park ecosystems would remain healthy enough and function normally enough so native species and biodiversity are protected without our heavy-handedness, but unless we shift our priorities dramatically then we’ll find ourselves stepping in at ever increasing rates.

We can no longer afford to think of parks as museums. What exists in them exists because we, directly or indirectly, choose it. In the face of unprecedented change, national parks cannot remain static. It wasn’t feasible in the past and it’s increasingly infeasible now. Where do we draw the line and how do we intervene? That’s something we need to decide right now—nationwide, collectively, and not in a piecemeal manner.

 

Northern Elephant Seals

Northern elephant seals are one of the largest pinnipeds on Earth. Large males can weigh as much as an SUV—four to five thousand pounds. Females are much smaller, topping off at only about one thousand pounds. Since the first few pairs began to haul out at Point Reyes in the 1970s, more and more have arrived each year.

seal resting on cobble beach, dock and boathouse in background

A subadult male elephant seal rests on a cobble beach in the Chimney Rock area at Point Reyes National Seashore.

This aggregation is a seasonal event. Unlike many mammals, the birthing and breeding season coincide in elephant seals. Males arrive first, establishing beach front territory where they’ll be able to establish and protect a harem. Pregnant females show up next, after which they soon give birth. Pups are weaned after about a month of nursing. Like bears, female elephant seals fast while giving birth and nursing. They do not eat, drink, or leave the beach during this time. Consequently, they lose 30-40% of their body weight during this short time. Mating occurs before the females depart to the open ocean. Adult males stick around longer, aiming to increase their chances of mating with as many females as possible.

Males have unique individual calls, and helps them recognize each other and avoid some physical conflict. While my mid January visit was too brief and my viewing was too far away to make such differentiations, there was plenty of activity to see and hear.

The biggest bulls already had established territories and harems. Newborn pups cried nearly constantly, especially when a wave of cold water washed over them. Females barked at each other too. For gregarious creatures, they sure let others hear it when their personal space is encroached upon.

(This place could really benefit from a webcam.)

The main overlook provided the best viewing opportunity to see bulls with harems. The females didn’t seem to be ready to mate, having just given birth or just about to, but that didn’t stop some of the bulls from trying. Forced copulation is not uncommon among elephant seals. Females can be seriously injured and pups crushed by randy males.

I also found good viewing opportunities nearby at the old U.S. Life Saving Station.

elephant seal resting on side with penis emerging

I had no idea what was going on here, but later learned this is an elephant seal’s penis. (Also, I’m told, these are nicknamed a “pink floyd.”)

Northern elephant seals were once thought to be extinct from decades of unrelenting and unregulated hunting, then a small population was found off of the Mexican coast in the early twentieth century. Luckily, the species was given strict protection while their ocean habitat remained largely intact, and their population has grown about six percent per year since the early twentieth century. There are now probably more than 150,000 northern elephant seals.

Many marine mammal species were once so rare that we can’t take them for granted, and we need to ensure their habitat and food sources are protected. If you’re in the neighborhood of Point Reyes National Seashore in January and February, you must stop and see elephant seals at Chimney Rock.

Drivers of Hibernation

Brown and black bears hibernate to avoid winter famine. For five to seven months, they do not eat, drink, urinate, or defecate, a strategy quite unlike other mammalian hibernators. Chipmunks, for example, cache food to eat in between bouts of torpor. Marmots and arctic ground squirrels don’t eat during winter and survive off of their fat stores like bears, but they activate their metabolism periodically to wake and urinate.

I recently spent about 40 hours reviewing studies related to hibernation and denning in brown bears for a chapter in my book on Brooks River’s bears and salmon, which reminded me just how remarkable this process is. While in the den, bears spend about 98% of their time not moving. Their heart rate declines dramatically from 50-60 beats per minute during summer to 10-20 per minute in hibernation. During this time, they hardly breathe, taking 1.5 breaths per minute on average. Their body temperature drops several degrees entering them into a state of hypothermia. Finally, the metabolic rate of a hibernating bear is 70-75% less than its summer peak. To survive, bears subsist on their body fat, catabolizing it into energy and water.

brown bear sitting on rock surrounded by water

All brown bears, like this adult male known as 89 Backpack, get fat to survive.

Despite their lack of physical activity, hibernating bears maintain muscle strength and bone health. Even if immobilization didn’t cause starvation, osteoporosis, and atrophy in people, we would die of dehydration if placed in an equivalent situation. Hibernating bears, however, are nearly completely self-supporting. The only input they need from the outside world during hibernation is oxygen.

The physiology of bear hibernation is complicated and not fully understood. Scientists are still elucidating basic details about this remarkable process. For example, what causes bears to enter and exit the den? How long do bears need to switch their metabolism from to hibernating mode? As it turns out, the switch is a long process.

Researchers in Sweden used implanted heart rate monitors and GPS-enabled tracking collars on fourteen brown bears. The devices recorded the movement, heart rate, heart rate variability, and body temperature as well as ambient temperature and snow depth. The results, published last year in “Drivers of hibernation in the brown bear,” are insightful because it allowed the researchers to develop correlations between the variables that drive and trigger hibernation.

In fall, well before hibernation begins, body temperature and heart rate of bears began to decrease. Heart rate started to slow, on average, 24 days before den entry, and body temperature began to drop 13 days before den entry. Overall activity lessened 25 days before entry, but metabolic activity declined steeply just as the bears entered their dens. It took an additional 20 days after for heart rate and metabolic activity to bottom out.

The transition back to a more active physiology started long before bears left their dens. Heart and metabolic rate began to rise one month and 20 days, respectively, before den exit. Body temperature began to rise even earlier, a full two months before den exit when winter still locked the landscape in ice and snow. All bears left the den when their body temperature was 36.7˚C (98˚F) ± 0.15 °C, the active-state body temperature for brown bears. As the researchers note, the narrow temperature range at this time suggests bears exit the den when their body temperature reaches a specific point. Body temperature and metabolic rate stabilized 10 and 15 days, respectively, after den exit, but heart rate didn’t stabilize for another month.

Graph that shows the timing of several variables affecting the start and end of hibernation in bears.

These graphs chart the relationship between physiological parameters of brown bears in Sweden. Den entry (left column) and exit (right column) are indicated by time zero (the green vertical line) to determine the sequence of physiological events. SDANN is the standard deviation of heart rate variability over five minute intervals. It was used a proxy measure of metabolic activity. A red line denotes when a variable was decreasing, while a blue line indicates when a variable was increasing, with the number of days from the entry/exit indicated. From Drivers of Hibernation in the Brown Bear and reposted under the Creative Commons Attribution 4.0
International License.

Even though the bears’ physiology initiates the ultimate beginning and end of hibernation, climate plays a role in this process too. Changes to body temperature before den entry were affected by ambient air temperature, but bears largely relied upon a physiologic slowdown to cool themselves. In spring, bears left the den when the weather was right, exiting when air temperature rose to above 3.7˚C ± 1.5 ˚C (38.7˚F ± 2.7˚F).  Some biologists have suggested that food availability drives the timing of den entry, but this study did not attempt to test the hypothesis.

As a survival strategy, bear hibernation is remarkably efficient, and no other animal attains the same physiologic feats. Small mammal hibernators wake to pee; bears don’t even need to do that. Changing from an active metabolism to one of hibernation and back again takes a lot of time. If you are fortunate enough to see a bear in the middle of fall or the middle of spring, that bear is likely living in a transitional body equipped to handle two worlds—one with food and one without.

 

Filling the Gaps

Last July on bearcam, we witnessed the ascent of 32 Chunk in the hierarchy at Brooks Falls. Chunk was the largest bear to consistently use the falls in July, and most bears didn’t challenge him. We watched Chunk interact with many bears, occasionally with some that I (and many bearcam watchers) didn’t recognize. In mid July, for example, we saw Chunk displace another large adult male.

GIF of bear on left moving away from approaching bear who appears at right.

In this GIF from July 2017, a unidentified bear avoids the approach of 32 Chunk.

At the time, a few bearcam watchers speculated the subordinate bear may have been 856, who was the most dominant bear at Brooks River for many years. As I wrote in a previous post, I didn’t think this was 856. So who was it? Was he a previously identified bear or a newcomer to the river?

Before his seasonal position ended this fall, Ranger Dave from Katmai posted photos of several bears who were seen along the river, but were unknown or unrecognized by webcam viewers. Assuming Ranger Dave’s IDs are correct, which they are much more often than not, the unknown bear in the GIF above could be #611.

brown bear standing in water

Bear 611 at Brooks Falls in 2017. Photo courtesy of Dave Kopshever and Katmai National Park.

611 is a bear I don’t know much about. According to my notes, he was first identified in 2015, but only in September and October not in July. Preliminary bear monitoring data from that fall state this bear was an older subadult or young adult at the time.

611_09162015

611 in September 2015, the first year he was identified. NPS photo.

I may be splitting hairs or misunderstanding Dave’s intent, but note that Ranger Dave said, “This is believed to be 611” when he posted the photo. Perhaps there’s still some uncertainty regarding the ID. Filling in the gaps of who’s who at Brooks River can be difficult, and it isn’t possible to identify every bear with certainty. But—based on scars, size, head shape, and ear color—I am fairly convinced the bear in the 2017 photo posted by Ranger Dave is the same bear that Chunk displaced in the GIF above.

At Brooks River, I made the effort to learn to recognize the bears who used the river frequently. Since bear behavior is often complex and can vary from animal to animal, recognizing individual bears leads to a better understanding of their growth, behavior, and strategies for survival. If 611 returns in 2018, we’ll have another opportunity to observe his behavior. Will he challenge other adult males for fishing spots or will he avoid confrontation more often than not? Whatever happens, it will allow us to learn just a little more about the bear world.