Caribou Migration


Spring caribouIf you want the once in a lifetime opportunity to photograph thousands, possibly tens of thousands of Alaska caribou in their ancient homeland in the Arctic National Wildlife Refuge (ANWR) , this 8-day backpack is the Alaska photography trip for you.

After some pretrip scouting by your guide, we’ll be dropped off on the gravel bar of the river giving us the best possible access to viewing the Porcupine caribou herd as they finish their spring migration and the cows begin to calve.

isuma1000x400Photographers will definitely want a nice long lens or two to get those award winning photographs. Longer lenses help keep us from impacting the caribou at this important time for them. There is also a good chance we’ll see grizzly bears, wolves and foxes as the tundra awakens with new life.
Prior wilderness or camping experience is not necessary for this trip however, please note that due to the logistics of this trip, group size is limited to six participants.


Caribou are the most numerous large mammals in the Arctic Refuge. Two herds occur there: the Porcupine Herd (named afer the Porcupine River) and the Central Arctic Herd. The Arctic National Wildlife Refuge is within the main range of the Porcupine Herd, which numbers approximately 152,000 animals, and on the periphery of the range of the smaller Central Arctic Herd with 23,400 animals.

The spring migration begins in early March as caribou gradually drift off toward the northern limits of their wintering areas. The Porcupine Herd follows three major routes to the North Slope from primarily wintering areas in Alaska and the Yukon Territory: the Richardson, Barn, and British Mountains; the Old Crow route, which crosses the Porcupine River near the settlement of Old Crow and continues northward through the Old Crow Flats, over the British Mountains and through the Firth Valley; and the Arctic Village/South Brooks Range route which crosses the East Fork of the Chandler River, the Sheenjek, and upper Coleen rivers and follows the Firth River into Canada where it joins the Old Crow route.


The caribou segregate themselves into groups which migrate at different times. Pregnant females along with some yearlings and barren cows are the first to migrate; followed by bulls and the remaining juveniles. In mid-to-late May the pregnant arrive on the North Slope, while the others follow a few weeks later.

Calving takes place during the last week in May and the first two weeks in June in the foothills and Coastal Plain between the Hulahula and Babbage rivers, and area that is generally snow free by early June. Caribou are not distributed evenly across the area; instead, they gather in more limited locations which vary from year to year.

As the mosquitoes emerge in late June and early July, the caribou gather into enormous post-calving aggregations, sometimes numbering in the tens of thousands. The caribou seek areas where breezes and cooler temperatures reduce the harassment by mosquitoes, and when there is no wind, the caribou move continually. Cold winds offer relief from the mosquitoes and permit the caribou to rest and feed freely.

By mid-to-late July, most Porcupine Caribou have moved off the Coastal Plain and into the foothills and mountains. Although some of the Porcupine Caribou occasionally remain on the North Slope for the winter, they usually travel south and east to Canada. When they do stay on the North Slope, the Porcupine Caribou usually move westward from the 1002 area and mingle with caribou from the Central Arctic Herd.

Fall caribou migrationThe fall migration may begin any time from late August to mid-October as the caribou start to move generally southward. This migration will carry the caribou one hundred to three hundred miles south into the area south of the Brooks Range, in the vicinity of Arctic Village, Alaska, and into the southern Richardson and Ogilvie mountains in the Yukon Territory. The caribou continue to lay on fat as they move south; the males will need energy reserves for the rut and all will need it during the winter. At this time, the bulls are shedding the velvet from their antlers and rubbing them against trees and shrubs. The bulls are also becoming increasingly aggressive, engaging in brief sparring matches.

The rut lasts for a two-week period in mid October. During this time the bulls fast, relying on their reserves of body fat. This brief breeding period helps to explain why the calving season is similarly brief. Even during the rut, the animals continue on to their winter ranges.