Sea of caribou, waves of insects

July 17, 2012 Posted by: Marci Johnson

CaribouAggregationsClipNational Park Service wildlife biologist Kyle Joly just released an update on the "spectacular" aggregations of the Western Arctic caribou herd. Every weekend Kyle receives an email that contains GPS coordinates from radio collars worn by 40 caribou, allowing him to monitor the routes and timing of the 2,000 mile round-trip migration between their winter range and the calving grounds. Kyle's account of the the post-calving aggregations he witnessed earlier this week can be found by clicking on the image above.

Previous issues include "Spring Migration Running Behind" and "Daring Dash Across Sea Ice". To learn more about the work being done by the NPS Inventory & Monitoring Program on Alaska's largest caribou herd and to see a map of their range, click here.

6 Comments Comments icon

  1. February 11, 2013 at 02:00

    It was nice to read about the caribou herd. prix achat maison

  2. August 19, 2012 at 03:17

    Discovery News highlighted Dr. Joly's photo and asked about the insects, too. You can find this article online at

  3. August 13, 2012 at 07:55

    Hi Kathi, The wood frog is also known as Rana sylvatica. Until we post a blog entry about them in Kobuk Valley National Park you can read more online at Caribou migrate great distances due (in part) to weather conditions, food availability, and insect harrassment. Some of the most productive areas of their summer range are too harsh to endure in winter, and with herds numbering in the hundreds of thousands they must also move to disperse their impact and avoid overgrazing. If a herd were to remain in one small area their food resources would be decimated. If you've had a picnic when a few mosquitoes were out you may remember being a bit uncomfortable, but if you can imagine being covered in mosquitoes and biting flies without any bug repellent you may sympathize with caribou. They move more often, stand less, eat less, and even though there is often little forage they seek out patches of snow and windy ridges for reprieve. Animal Planet's Fooled by Nature segment on caribou migration ( illustrates this well, as does the film Being Caribou (time 0:56:40 at Thank you for your questions and for visiting the Running Herd blog...

  4. August 10, 2012 at 05:02

    Waht is the Scientific anme of this wood frog?

  5. August 10, 2012 at 05:01

    I sitll don't get why they herd up in response to insects. Also can you explain why they migrate? Highlands to lowlands in spring?

  6. July 20, 2012 at 01:01

    The images are mind blowing. Fascinating article! Who knew the pesky insects could cause this majestic wonder of nature!!! Great blog! Thank you, from 2 new blog followers.

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