A New Study Finds That Many Pronghorn Migrate Hundreds of Miles Each Year, Often Struggling to Overcome a Growing Number of Obstacles Along the Way
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A new study finds that many pronghorn migrate hundreds of miles each year, often struggling to overcome a growing number of obstacles along the way. BY BEN LONG LONG ROAD HOME A herd of several hundred pronghorn migrates north across Montana near Fort Peck Lake toward spring fawning grounds in southern Can ada. In some years the animals will travel hundreds of miles during their seasonal migrations. PHOTO BY MICHAEL FORSBERG 8 NOVEMBER –DECEMBER 2011 FWP.MT.GOV/MTOUTDOORS MONTANA OUTDOORS 9 nder the big sky of the high plains, species is like the pronghorn. Its closest ge - a herd of pronghorn stands out netic relative is, of all things, the giraffe. amid the sage and bunchgrass, Pronghorn have lived in North America the tallest natural features along for millions of years, surviving glacial eras, U the skyline. They snap to atten - volcanic ash winters, and predation by the tion the moment a truck slows, and when now-extinct American cheetah. But it took the vehicle stops and binoculars come out, humans only 50 years around the turn of the the animals trot off over the horizon. 20th century to nearly wipe out the animals. This vast, open country that scientists call After explorers and trappers opened the the Northern Sagebrush-Steppe Ecosystem West, the teeming herds of wildlife observed seems an unlikely place for secrets. But until just a few decades earlier by Lewis and Clark recently, pronghorn possessed an important were quickly overrun. Ambitious pioneers one—the location of core habitats and the punched railroads and telegraph lines across routes they use to migrate throughout the the prairie, plowing arable land and replac - year. Now scientists are discovering these ing hoofed wildlife with cattle. Pronghorn critical summer fawn rearing areas, winter - were shot by hungry farmers and unregu - ing sites, and ancient pathways along which lated market hunters. By the early 1900s the the prairie denizens move back and forth total pronghorn population in North Amer - across portions of the northern Great Plains ica was reduced to fewer than 15,000. each year. They’re also finding what obsta - Conservation-minded hunters and land - cles—natural and man-made—impede the owners eventually repopulated the plains animals’ migrations. The research is timely with the fleet-footed animals. Working with and essential. Natural gas wells, oil pipe - state bi ol ogists, they trapped pronghorn in lines, wind turbines, housing subdivisions, population strongholds and relocated the an - and other developments in northern Mon - imals in historic habitat. Within decades, tana and Can ada’s prairie prov inces con - pronghorn had recolonized the American tinue to expand. Unlocking the secret West, although in nowhere near pre-settle - to the pronghorn’s mysterious spring and ment numbers and only in marginalized frag - fall migrations is critical to finding ways ments of their historic range. Today, to ensure that these age-old seasonal move - pronghorn number over 1 million across ments can continue. North America. In some parts of the West they are common enough to take for granted. PULLED BACK FROM THE BRINK Yet pronghorn populations remain vulner - Though commonly called antelope, prong - able. According to northeastern Montana horn are not related to gazelles, eland, or wildlife managers, the severe winter of other true antelope species, which are native 2010-11 cut populations in much of the only to Africa and Asia. Pronghorn are an region by 70 percent. Of more long-term con - endemic North American ungulate, a cern, say biologists, is the increasing difficulty holdover from when mastodons, ground pronghorn have in making their seasonal mi - sloths, and other ice age mammals roamed grations. Housing and fencing are spreading the continent. In all the world, no other out from new subdivisions across southern SPREADING THE WEALTH A Montana Department of Fish and Game pilot hazes pronghorn into a trap on Townsend Flats near Helena in the mid-1940s. UNFAMILIAR TERRITORY Captured by a Thousands of the animals were N remote-sensor camera, migrating pronghorn in O I trapped from strongholds and T C E northern Wyoming find easier winter walking in transplanted during the mid-19th L L O a river valley willow thicket. In severe winters, C century to restore a population O T Mon tana pronghorn take similar routes through O that in Montana had dwindled H P riparian areas and cattail marshes—and even to just 3,000. S A C onto railroad tracks and county roads—in order U L S I C I to move across snow-filled landscapes. R M E M I O J J 10 NOVEMBER –DECEMBER 2011 FWP.MT.GOV/MTOUTDOORS MONTANA OUTDOORS 11 Canada. New roads, pipelines, and oil and tect winter range and fawning grounds as many of the research animals on historic mi - Decades ago, waterfowlers and biolo - Alberta to work together more coopera - gas wells are spreading across many parts of well as ensuring that landscapes remain gration treks in search of food and milder gists learned that ducks often travel vast tively and pay attention to habitat condi - the northern Great Plains—from the Pinedale permeable for highly mobile wildlife. conditions, allowing Jakes to document distances, many nesting in Canada’s prairie tions on both sides of the border. “If we Anticline in Wyoming to the Bowdoin oil State wildlife agencies such as Montana some of the longest land migrations ever pothole region then wintering in the warm want to manage for pronghorn hunting in fields northeast of Malta to the coal-bed Fish, Wildlife & Parks knew the locations of recorded in the lower 48 states. In a single wetlands of Mississippi, Louisiana, and northern Montana, we can’t just look at Pronghorn have methane wells in southern Alberta. The re - some core prairie wildlife habitats. But they year, some animals traveled more than 300 Texas. By putting leg bands on ducks and where the animals live during the hunting “to put their foot in sulting development pushes its way into lacked data on others, as well as on the miles. One intrepid pronghorn, number 169, tracking where the birds were shot by season,” he says. “We have to also consider established wintering habitat and summer routes pronghorn follow as they move be - was tracked starting near Glasgow as it hunters, biologists began mapping water - what’s happening hundreds of miles away every little bit of grounds where pronghorn rear their fawns. tween those sites. That’s where Andrew moved north to Saskatchewan’s Grasslands fowl migratory routes, along with prime in Canada.” Even worse, it chops great swaths of prairie Jakes came in. National Park in spring. Then in fall it wetlands for nesting and overwintering. Just as important as conserving core their path. So what habitat into isolated pieces. The resulting In 2008, the Helena-based University of headed back to Montana, where severe win - Also documented were critical resting and habitats is maintaining pronghorn migra - landscape fragmentation les sens what con - Calgary doctoral candidate began a trans - ter weather pushed it south all the way to In - refueling “stopover” sites, such as shallow tion corridors. “Ducks can fly over the tops happens on the servation biologists call “connectivity”—the boundary study of pronghorn core habitats gomar—a total annual trek of more than 350 temporary wetlands. Private conservation of most barriers,” says Gates. “But prong - degree to which pronghorn and other wildlife and seasonal movement in Montana, south - miles (see a map of the trek on page 14). groups such as Ducks Unlimited, along with horn have to put their foot in every little bit landscape is freely move from one place to another. ern Alberta, and southern Saskatchewan. The “The scale of these migrations is beyond state, provincial, and federal wildlife agen - of their path. So what happens on the land - To find a balance between the needs of study is funded by the Bureau of Land Man - those of African wildebeest and right up cies, began protecting, conserving, and scape is critically important.” critically important.” HARD GOING Historically able to follow bison herds that acted as snowplows, pronghorn now must break trail themselves. The animals are ill equipped TRAIN WRECKED Deep snow forces pronghorn to travel along railroad corridors. Last winter hundreds trying to migrate along tracks were killed by to negotiate drifts like those that piled up across northern Montana this past winter. In any year, fences pose constant problems. If pressed, pronghorn can trains in northeastern Montana, such as this section of line northwest of Glasgow. Cars and trucks are no friendlier. As human development grows leap over obstacles, but they have not evolved to do so easily, as elk and deer have. In winter, they squander precious energy trying to bypass fences. across the northern Great Plains, so do highways and collisions between migrating pronghorn and moving vehicles. grassland wildlife and those of economic agement, the World Wildlife Fund, FWP, and there with the barren ground caribou’s,” restoring critical waterfowl habitats in the BLOCKING THE WAY Alberta headed to Montana when the growth, western states and prairie provinces the Alberta Conservation Association. says Cormack Gates, professor of Environ - United States, and even more so in Canada. A major impediment to pronghorn survival weather turned cold. The pronghorn gath - have begun to identify core habitats and mi - Jakes aims to learn how human activi - mental Science and Planning at the Univer - Pronghorn appear to require a similar is deep snow. The animal’s tiny hooves, per - ered in herds of up to 1,000 animals and S I gration routes so development can be sited ties affect pronghorn habitat and move - sity of Calgary.