News Release

Who goes the farthest?

Date: October 25, 2019
Contact: Kyle Joly, 303-969-2746

ANCHORAGE, Alaska— Alaska is known for its large populations of free-ranging wildlife. Many Alaskans take great pleasure in the opportunity to hunt, photograph or just view them. People journey from around the world come to parks such as Denali in the hopes of spotting animals such as wolves and caribou. Caribou, in particular, are often credited with the longest terrestrial migrations in the world, though without much scientific support. An international team of scientists, including Kyle Joly (National Park Service), Elie Gurarie (University of Maryland) and Mark Hebblewhite (University of Montana), gathered GPS collar data from around the world to address the question: which large terrestrial mammal migrates the farthest in the world? Long-distance migrations are threatened around the world, yet are critical for the conservation of many iconic species. Recognizing that not all mammals migrate between ranges, the team also determined how far these mammals moved during the course of a year.

The team’s findings have just been published in the journal Scientific Reports. In their work, the team measured 2 metrics of movement: round-trip migration distance (distance between the start and end of migration) and total annual movement (total distance the animal moved in a year from GPS collar data). Caribou, from numerous populations, were indeed found to have the longest existing migrations, with the round-trip distances exceeding 745 miles (1,200 km). Surprisingly, a few species such as gray wolves and khulan (Mongolian wild ass), while not migrating in a regular manner like caribou, travelled even greater annual distances. A gray wolf from Mongolia captured the title of top terrestrial mover, having traveled 4,503 miles (7,247 km) in a year; further than a walk from Prudhoe Bay to Anchorage….and back….three times in a row. "What was fascinating about this study is how quickly it escalated. What started as a narrow effort to set the record straight on caribou migration morphed into this globe-spanning survey of long-distance movement - and then touched on all kinds of ecological relationships, between predator and prey, habitat features, and human impacts." says Dr. Gurarie.

The team discovered interesting patterns among these big movers. First, not only can predators keep up with their prey, they are often required to move much more in the course of their search for a meal. In Alaska, gray wolves moved more than caribou or moose. Second, small prey animals from the same region tended to move more than larger ones. For example, caribou moved more than moose in Alaska, wildebeest more than zebras in the Serengeti, and khulan more than wild camels in Mongolia. One possible explanation of this pattern is that large animals are capable of using lower quality food sources which are more abundant, and this allows them to move less overall. Lastly, higher movement rates by herbivores were associated with lower vegetative productivity. The less food that was available, the more they moved, likely to acquire sufficient resources. The greatest movements were found in areas of very low human disturbance, which highlights the effects of habitat fragmentation and human development. Dr. Hebblewhite notes that “One of the most amazing aspects of this study is the simple fact that large mammals, from around the globe, need so much habitat to move. Seasonal migrations, predator-prey dynamics, and the need to obtain food drive these astonishing long-distance movements. Our study builds on a growing body of science that show human activity can negatively affect animal movements and populations, and our work emphasizes the need to maintain core habitats and connectivity to keep these animals on the move.”

Find their report here (www.nature.com/articles/s41598-019-51884-5) to read more about their work in detail or view a National Park Service overview here (www.nps.gov/articles/worldmigration.htm).

 



A single wolf stands in foreground. A herd of khulan run in the background.
Gray wolves in Mongolia travel more than prey, such as the khulan (both pictured here). These wolves were found to move more than any other terrestrial mammal.

Photo: Dejid Nandintsetseg

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A herd of elk gather near a small pond. Mountains with a dusting of snow are in the background.
Elk migrating in the Rocky Mountains.

Photo: Holger Bohm

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A herd of caribou run across a shallow river. Snow covered mountains are in the background.
Caribou splashing across the Kobuk River on their fall migration.

Photo: NPS/Kyle Joly

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A close up view of several khulan. One is looking directly at the camera. The landscape is flat and grassy. Khulan are horse-like.
Khulan in Mongolia move than any other ungulate the researchers studied.

Photo: Petra Kaczensky

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A herd of wildebeest stand near the camera. One is staring directly at the camera. The animals have a long main, and horns.
Wildebeest migration in the Serengeti.

Photo: NPS/Kyle Joly

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A large group of caribou swim across a river. The water is darker and looks cold. The landscape appears to be late fall or early winter.
A large group of caribou swimming south towards their wintering grounds.

Photo: NPS/Kyle Joly

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A group of caribou cross a river by walking and swimming. The snow covered Waring Mountains are in the background.
Caribou crossing the Kobuk River with the Waring Mountains looming in the distance.

Photo: NPS/Kyle Joly

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Two khulan near a watering hole. One is raising its rear legs in what looks like a kick towards the one khulan. The second khulan is raising its head to avoid the kick.
Khulan near a watering hole in Mongolia.

Photo: Petra Kaczensky

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A group of khulan walk nearly in single file on the rolling landscape of Mongolia.
A group of khulan in Mongolia.

Photo: Petra Kaczensky

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A close up of a wolf sitting in the snow. It seems to be relaxed with snow collected on the sides of the snout. The wolf appears dark in color next to the snow.
A gray wolf from eastern Alaska was found to be one the world's top moving terrestrial mammal.

NPS/Kyle Joly

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A group of camels loosely standing together on the rolling landscape. Several have their heads down as if they are grazing. One seems to be standing at alert.
Wild camels in Mongolia traveled long distances, likely because of the low productivity of their environment.

Photo: Adiya Yadamsuren

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Three zebras stand near the camera. They black and white stripes are very prominent. The animals visually appear to be horse-like, the mains are short and appear to be stiff.
Zebras in Tanzania during the dry season.

Photo: NPS/Kyle Joly

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Two wolves laying on the ground next to each other. One is looking at the camera. Thee is a small dusting of snow on the ground.
Gray wolves resting in eastern Alaska.

Photo: NPS/Kyle Joly

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Last updated: October 25, 2019

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