New Maps For Ungulate Migration Routes Across the Western U.S.

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Large ungulate” is a scientific term for a hoofed mammal such as a bison, mule deer, elk, pronghorn, and moose. The group is also colloquially known as “big game animals.”

Besides their elegance and strength, these iconic creatures are also known for their exquisitely long migration routes. Fascinatingly, many of these animals had followed the same migratory paths since before the United States was founded.

A bison with six starlings on its back.  Bison will scare up insects disturbed by their grazing and movement. This makes their backs ideal perches for insect eating birds. Photo: Wind Cave National Park, NPS / Kim Acker, public domain.
A bison with six starlings on its back. Bison will scare up insects disturbed by their grazing and movement. This makes their backs ideal perches for insect eating birds. Photo: Wind Cave National Park, NPS / Kim Acker, public domain.

Despite this phenomenon being known for quite some time, there were no modern unified maps of the ungulate migration routes. Precise mapping of migration routes contributes to conservation since it helps scientists and decision-makers exclude some sensitive areas from development and offers better land stewardship opportunities for private landowners.

Now, federal and state wildlife biologists have come together to create a unique map of ungulate migrations across the American West.

Mapping the Migration Routes of Ungulates in the United States

The new report, Ungulate Migrations of the Western United States: Volume 1, has mapped more than 40 ungulate migration routes in the states of Arizona, Idaho, Nevada, Utah, and Wyoming.

What is special about this study is that research data is more precise than ever, largely due to the now-standard use of GPS tracking collars that has gained traction in the last two decades. During the process, millions of GPS locations were finally translated into standardized migration maps – a step which the lead author Matt Kauffman calls “long overdue.”

A group of elk in Lamar Valley, Yellowstone National Park.  Photo: NPS/Neal Herbert, public domain.
A group of elk in Lamar Valley, Yellowstone National Park. Photo: NPS/Neal Herbert, public domain.

The report’s key takeaways are that (1) migration is necessary for large game creatures to secure the best food, and (2) that migrations definitely show a seasonal pattern. In the warmer months, the most nutritious (and presumably, delicious) forage is in the mountains. However, animals retreat to lower elevations as winter sets in, and snow cover takes over their pasturelands.

Besides providing us with new knowledge, the new maps have a higher practical purpose – they help scientists and land managers to take necessary steps to keep the vital migration routes open and functional to sustain a healthy population. 

USGS Director Jim Reilly stated that “This new detailed assessment of migration routes, timing, and interaction of individual animals and herds has given us an insightful view of the critical factors necessary for protecting wildlife and our citizens.” 

Migration corridors, stopovers, and winter ranges of the Kaibab North mule deer herd. Map: USGS.
Migration corridors, stopovers, and winter ranges of the Kaibab North mule deer herd. Map: USGS.

Why is Mapping Ungulate Migration Routes Important?

Reilly’s statement gives us a hint why mapping these routes is so important.

The ever-increasing changes in land use – driven by an expanding human population – are altering the natural habitats of large wild herbivores.

When migratory routes are unknown, urban development, industrial projects, agricultural fields, roads, fences, and other obstacles can and do intercept them, making it hard for animals to navigate and get to their traditional foraging grounds.

Add to that the changing seasonal patterns of vegetation due to climate change-induced droughts, and you get a clear picture of increased pressure on populations. 

A herd of caribou swims across the Noatak River in Alaska, heading south for the winter. Photo: NPS, Noatak National Preserve, Alaska, public domain.
A herd of caribou swims across the Noatak River in Alaska, heading south for the winter. Photo: NPS, Noatak National Preserve, Alaska, public domain.

That is where mapping comes to the rescue. Detailed maps can help to identify the key migration routes, as well as the structures that interfere with them. That allows conservationists to work with landowners to protect the corridors and vital habitats.

Another perk is that the migration maps also help monitor the spread of contagious diseases, such as the chronic wasting disease – a transmissible prion disease increasingly seen in North American cervids such as deer, elk, and moose. Efficient monitoring of disease spread enables the officials to take steps towards containing them.

As one can see – and the Western states can testify – successful wildlife conservation goes hand in hand with the development of new tracking and mapping techniques.

Credits: The migration mapping effort was facilitated by the Department of the Interior Secretary’s Order 3362. Besides the state wildlife managers, the report was co-authored by biologists from the USDA Forest Service, the National Park Service, the Bureau of Land Management, and others. The maps were produced by cartographers from the USGS and the InfoGraphics Lab at the University of Oregon.

To explore the Western Migrations on the web, visit the project’s online version.

References

The Study:

Kauffman, M.J., et al. 2020. Ungulate migrations of the western United States, Volume 1: U.S. Geological Survey Scientific Investigations Report 2020–5101, 119 p., https://doi.org/10.3133/sir20205101 and https://pubs.er.usgs.gov/publication/sir20205101

The Article:

Sobieszczyk, S. (2020, November 12). New maps document big-game migrations across the western United States. USGS.gov | Science for a changing world. https://www.usgs.gov/news/new-maps-document-big-game-migrations-across-western-united-states

Other:

Western Migrations Wildlife Corridors And Route Viewer: https://www.westernmigrations.net/

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