Migration Memories

Close up of bear feet

There are places in Yellowstone National Park where alternating grizzly bear footsteps are worn deep into the earth, forming trails that lead to very specific sites at geothermal vents. These footsteps are almost sculpted into the ground as each bear places its foot precisely into the tracks of its predecessor, rubbing its feet sideways in each track. Arriving at the site, the bears begin to eat the soil, high in potassium and sulfur. One theory is that the sulfur helps rejuvenate their digestive system after the long inactivity of hibernation, and they may be low in potassium after their winter’s fast. How do they know to go there? Does each bear rediscover this for themselves, or is it past knowledge, hard earned, passed on from generation to generation? Is the knowledge of these trails and sites or passed on through teachings from mother to cub, or a sort of grizzly energy that they pick up—a subtle sense that this is where other grizzlies have tread before me and so too I will go? Perhaps it holds a seed of information of how migrations may begin. Animal movements, large and small, are mysterious, fascinating events.

From the highlands of Yellowstone National Park to the sagebrush steppes of southern Wyoming’s high deserts lie ancient trails worn deep by a thousand generations of animals, notes Meredith Taylor of Restoring Wild Patterns. As the snows drift down into the mountains, deer, moose, elk, and antelope move to lower ground, searching for open areas where travel requires less energy, the cold is less bitter, forage and water are easier to find and there are no snowdrifts that make them vulnerable to predators. For thousands of years, the animals have migrated in a rhythm as primal as a heartbeat, followed by their human and animal hunters; bringing nutritional riches to insects, birds, reptiles and small mammals whose fate may depend on the annual migrations. Despite a daunting series of obstacles put in their path by humans, each fall, great waves of pronghorn antelope, mule deer, and elk continue to follow these trails from high summer ranges to their windswept, snow-free winter ranges, as Taylor beautifully describes it, returning in the spring to fatten up in lush meadows and give birth to the next generation. Writes Joel Berger, a biologist with the Wildlife Conservation Society, “Among the earth’s most stunning, yet imperiled biological phenomenon is long distance migration. Between Tierra del Fuego and Toronto five species from the same region of the Rocky Mountains in the USA still experience the largest of the remaining New World long distance migrations near or in the Greater Yellowstone Ecosystem…. about 75% of the migrations routes for elk, bison and… pronghorn have already been lost…. none the less annual round trips of pronghorn exceed travel distances of elephants and zebras and are on a par with the African wildebeest.”

For nearly 200 miles, the animals travel, from deep in Yellowstone, south over divides, through the Gros Ventre, Snake, Hoback and Green River drainages into the open sagebrush expanses of the Green Valley, the Wind River Basin, the Red Desert, and the Little Colorado Desert. This was once one of the richest wildlife habitats in the world.

“The great semi desert area lying in southern Sublette and Fremont Counties and northern Sweetwater County, in western Wyoming, until 1913 was undoubtedly one of the greatest wildlife wintering areas in the United States. Upon this rolling, broken land thousands of buffalo, elk, antelope, mountain sheep and sage grouse found the light snowfalls to be of insufficient depth to hamper them in securing ample quantities of the highly nutritive, sparse vegetation… Parts of shed elk antlers, occasional mountain sheep and buffalo skulls still bleaching on the desert, as well as mounds of collected antlers and skulls about many of the ranches in the valley still furnish evidence of the animals that used the early migration routes. The heavy beamed, immensely burred, eight-pointed elk antlers may indicate a high nutritive quality of the forage at that time.”[1]

According to Frank Dunham, M.D., in an 1898 issue of the magazine Recreation[2], “I have seen large bands of elk, in November, making their pilgrimage to the red desert country. Many of the readers of Recreation will remember reading Mr. Yarnell’s story, ‘3000 Elk.’ That band was on its way to the same winter feeding grounds. Mr. Dodge say fully 20,000 elk pass his place every fall (near Cora), all bound for the same winter range.”

The small, graceful pronghorn antelope is the sole surviving member of an ancient family that dates back 20 million years. It is an astounding creature able to reach a top speed of 60 miles per hour. In historic times, an estimated 40 million pronghorn mingled with immense bison herds across the American West. By the early 1900’s slaughter for meat and hides had reduced the number to fewer than 20,000, with an estimated 5,000 in Wyoming. Yet despite the carnage, for more than 7000 years, a subgroup of this delicate animal continued to migrate 170 miles from what is now Grand Teton National Park to their wintering grounds, following traditional routes passed on from mother to young. Archaeologists have found remains of antelopes killed 7,000 years ago by human hunters taking advantage of the migration through the narrowest bottleneck at Trappers Point. The bones of fawns and unborn fetuses indicate that they migrated back to the Teton Range in early spring. And they continue to migrate back, in early spring, navigating 47 fences along the way—fences they will not leap but must crawl under or go around, past innumerable homes where they are chased by dogs, and through bottlenecks as narrow as one half mile hemmed in by human development. But still they come.

There is a great mystery here.  According to Kim Berger, a biologist with the Wilderness Conservation Society, “In 1907, the pronghorn failed to return to the Tetons. The migration did not decline slowly over a period of years; rather, the herd for some reason just stopped coming. This absence lasted for nearly 50 years until a small herd re-established one of the traditional migration routes during the 1950’s. Since then despite obstacles, the pronghorn have continued to return every year…”

Why did they stop? Why did they begin again? How did they keep, or retrieve, their memory?

The big horn sheep have lost their memory and with it, their ability to move to good winter range. The Teton River on the west side of the Tetons is excellent bighorn habitat but there have been no sheep there for 100 years. They have not moved back again. A few old folks still remember bighorn sheep using Fox and Darby Creek. There were bighorns in the Big Hole Mountains until 1900. But hunting and poaching and disease from domestic sheep killed off animals who remembered how to get there. The lower Snake River area is no longer used. According to Mike Whitfield, a biologist at the Teton Regional Land Trust, “Big horn sheep are very traditional in how they learn and when they lose the memory they do not seem to regain it. They are not exploratory creatures and if their memory of a path is lost, they are not likely to recolonize.” Because of development cutting off old paths along creek corridors and the lost guidance of the elderly ones, the sheep now winter at 10-11,000 feet. They feed on what forage they can find, wearing their teeth down prematurely. Few lambs survive.

But the urge to spread ones genes is strong, and some on the east side of the Tetons still have memory. A few rams are found every year trying to cross the fences of the National Elk Refuge to Buttes on the other side. The fence cuts off genetic interchange between the Gros Ventre and Teton populations. The Teton Range, the Gros Ventre, the Snake River Range and several others all had bighorn sheep, and the rams would travel between them during the rut. Their current isolation prevents their genes from mingling in other pools, causing inbreeding and a decline in vitality.

For some elk, the memory remains. Some migration routes of elk to winter feeding grounds documented in 1898 remain essentially the same. For others, we do not know if they have forgotten. As ranchers moved in and took over elk habitat, cutting hay and fencing, the starving animals raided rancher’s haystacks. At the time, feedings seemed like a good way to protect the haystacks while preserving the elk for hunters, and wildlife managers began the custom of elf feedlots. One of the results is that elk from the Upper Green summer ranges, Gros Ventre Valley, Jackson Hole, Teton Wilderness, and southern Yellowstone Park no longer migrate. The 23 elk feedlots “shortstop” the migrations, acting as dams do on a river system, stopping salmon. The last major elk migration from the Upper Green was in 1917. Today, only a few elk leave the feedlots for their traditional wintering grounds.

Bison, bighorn sheep, and moose once completed lengthy treks between their summer and winter ranges, but their journeys have been shortened, and in some cases completely blocked, by habitat alteration and human interference. The west was settled without understanding or regard for natural patterns of movement. Animal pathways from mountains to grasslands were blocked by fences, homesteads and ranches. Even as we begin to work to preserve the big game herds, we did not think to include the animals’ needs. Our delineation of national park borders was based on political considerations rather than the need to encompass functional ecological systems. More than a hundred years ago, visionary conservationists proposed five winter-game preserves to protect migration routes and winter ranges from Yellowstone National Park to the Green River Basin. In 1898, Frank Dunham wrote, “I have sent you a map of this country, in which you can see the Jackson’s Hole preserve as it would be if extended from the National Park. Also the game preserve on the red desert, and the trail elk and other game take in going to their winter range. … If the LAS can pull this scheme through Congress, it will be one of the greatest triumphs for game protection yet achieved… we are thoroughly aroused to the necessity of immediate action if we could afford adequate protection for our game… This is a most excellent proposition, and the officers of the LAS will undoubtedly present a bill to Congress at its next session, asking that the Park list be extended so as to include the portion of the red desert indicated on the above map.” But many local ranchers and landowners perceived this as a “federal takeover” of lands between the Gros Ventre and Green River. Only three of these preserves were created: the Teton Wilderness, the National Elk Refuge, and the Izaac Walton League addition to the refuge.

We continue talking about “federal takeovers” today, continue cutting off corridors despite our new awareness. For example, the local Wyoming Department of Transportation has planned to greatly enlarge the road going through Togwotee pass, a road thousands of elk and mule deer must cross in their yearly migration between summer habitat in the Teton wilderness and winter ranges in Jackson Hole and the Wind River Valley. But there is a good deal of hope, things we can do if we are wise enough and strong enough. We understand better now the time and scale on which nature works; that migration and motions are the nature of nature; and that stopping the movement of genes will eventually stop the flow of life. The fundamental insight of a hundred years of ecological study is that everything is connected and fragmentation of habitat is a major cause of the increasing rate of extinctions. Animals must be able to migrate, or perish. They cannot survive over time in the islands of habitat we have allotted them.

We are applying this knowledge now, taking steps to preserve migrations. We are working to preserve corridors. The Yellowstone to Yukon Conservation Initiative would preserve wildlife corridors for 2,000 miles. Others are working around the country to preserve corridors in their areas. Reentry of top predators such as wolves may help restore ecosystems—for example, the aspens and willow are coming back in Yellowstone as the wolves change the grazing habits of the elk. According to Kim Berger, nearly 90% of the pronghorn fawn mortality was due to coyotes, a possible combination of overpopulation of coyotes and lack of good hiding habitat left. The wolves have cut the coyote population by 50%. Joel Berger has suggested the creation of a formally protected National Migration Route. Through planning and zoning boards, we can develop land while still taking migration corridors and key habitats into consideration. Gray wolves, cougars, and grizzlies are beginning to move back to ancestral habitat south and east of Jackson Hole. Recently, a wolf found the ancient corridor to the wintering grounds of southern Wyoming, and three bison made it as far as the Upper Green River before they were shot for fear of brucellosis. They remember.

Very few elk escape the feedlots, but some do. Mule deer herds continue to travel up to 100 miles between the Salt River Range, Hoback Basin, Wyoming Range, Wind River Range, Gros Ventre Range, and Snake River Range, converging to winter in the sagebrush steppes of the Green River Basin—the longest recorded migration for their species. Chased by dogs, stopped by fences, terrified by roads, and yet the antelope come, driven by an irresistible urge. Bighorn sheep are seen trying to cross fences of the Elk Refuge. Driven by urges not to be withstood, with courage, heart, and determination, the animals try to get to better range where their young can get enough nutrition, where they can procreate without inbreeding, where they have a chance to continue the survival of their kind.

The Teton area is an extraordinary place. These ancient migrations, still a vibrant remnant of what was, followed by humans since time immemorial, stir the blood, make the season turn, and tune us to the rhythms of nature. For those of us humans alive today, this is our time in the advancing tide of life. We are the carriers of the past and the determinants of the future. May we not lose our memory.

Information for this article has been excerpted from many sources and helpful concerned biologists and conservationists, not the least of which are Lloyd Dorsey and Meredith Taylor of Restoring Wild Patterns and Joel Berger of the Wildlife Conservation Society. For more information contact: Susan Eirich at wildlife@earthfireinstitute.org, Meredith Taylor at metaylor@wyoming.com, Lloyd Dorsey at ldorsey@greateryellowstone.org, or Joel Berger at jberger@wcs.org.

[1] Allred, W. (1950). In Fifteenth North American Wildlife Conference (pp. 597-598). Cheyenne, WY: Wyoming Game and Fish Commission.

[2] Dunham, F. (1898). Recreation, (IX), 272.

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