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May 19, 2005

Last Stand for Caribou?

Caribou_pic We've heard a lot about caribou recently, mostly in the fight over drilling in the Arctic National Wildlife Refuge. But fewer people know that the Northwest is home to the last remaining caribou herd to inhabit the lower 48 states. They are considered the most endangered large mammal in the continental United States.

Woodland caribou once ranged in New England, the Upper Midwest, Caribou_range_1and as far south as the Salmon River in Idaho. Today, the last survivors, the tiny Selkirk herd, occupy only a small range in northeast Washington, northern Idaho, and an adjacent portion of British Columbia. Even in BC, where caribou are relatively abundant, their range has shrunk dramatically as logging, development, and other habitat disruption makes itself felt in the Canadian Rockies. (Click on the small map at right for a look at present and historical range.)

The Selkirk herd has mimicked larger trends in North American caribou. Once numbering between 200 and 400, the herd has clung to a precarious existence since its listing as an endangered species in 1993. At present, the herd comprises only 35 animals, down from a recent high of 52 in 1995, which was achieved partly by three years of "augmentation" during the late-1980s when caribou from northern BC were transplanted to sustain the dwindling population.

Caribou_pop3 The causes for the decline of caribou are many. In order to thrive, woodland caribou require relatively intact mountain forests. (Their preferred food is a lichen found only on subalpine trees at least 50 years old.) So, in that sense, their fading populations are a good proxy for the extent to which we have disturbed these ecosystems. (For a look at the Selkirk population trend, click on the chart at left.)

In the Selkirk Mountains, for instance, clearcut logging, together with the road network to support it, reduced high-quality habitat and forage for the caribou. But logging had another, more pernicious, effect: the re-growth was abundant forage for deer, whose population boomed, followed quickly by a booming population of cougars. Cougars, who had formerly been rare in the Selkirks, would often bump into caribou and decide they didn't mind a little variety in their diets. So, "natural" predation turned out to be a big pressure on the few remaining caribou.

Over the last five to six years, the population has been fairly stable, hovering in the mid-30s. Officials credit this partly to aggressive cougar-hunting that has depressed the local cat population and given the caribou some breathing room. 

To be sure, there are other big stresses on the caribou too. Most notably, winter recreation, especially motorized recreation such as snowmobiling, can disturb caribou and force them to burn precious wintertime calories. In BC, other forms of recreation--heli-skiing and snow-cat skiing, in particular--appear to be accomplishing much the same thing for caribou populations. Experts even think that backcountry skiers may stress the animals.

The future of the Selkirk herd is very much in doubt. Without further augmentation, the herd is unlikely to survive. Fortunately, BC is planning to transplant 60 new animals to the herd over the next 6 years. (It was supposed to start this year, but was delayed.) If predation stays low and human impacts are minimized, the Selkirk caribou may yet have a chance at surviving, in the short-term.

Over the long-term, the only chance for caribou to inhabit the lower 48 will be improved habitat and more of it. That means strict conservation for old-growth forests and careful conservation and restoration in areas that can return to old forest conditions. One excellent way to begin this task--and also reduce human stresses--would be to expand Washington's Salmo-Priest Wilderness, at the heart of the Selkirk herd range. There's a 17,585-acre roadless area in Idaho's national forestland, adjacent to the wilderness, that is ripe for inclusion and the stricter management that would bring.

Posted by Eric de Place | Permalink


Thanks for the very timely caribou posting. As you point out this is an animal that most folks here don't even know we have. Just to clarify a couple points if I may. The South Selkirks herd (Canadian nomenclature) is part of the "southern mountain ecotype" of woodland caribou or "mountain caribou". Not to split hairs, but the distinction is important as these are the only mountain caribou in the world. The Inland Rainforest or "wet belt" forest in which they live is also globally unique.

While they are technically a woodland caribou these are the only animals that have adapted to the mountainous terrain of the Inland Rainforest of the Columbia and Cariboo Mountains, where they rely almost exclusively on arboreal lichens in late winter. That's the primary distinction. Incidentally, these lichens only start to appear in abundance in forests over 80 to 120 years old, not 50 as stated in the blog.

Again not to split hairs but you state that these animals are "relatively abundant" in British Columbia, which I think misses the point a bit. Mountain caribou have declined from 2400 animals in 1997 to about 1670 today and the trends are steadily downward with no herds increasing.

The "northern mountains ecotype" found in less precipitous terrain north and west of the Columbia Mountains numbers about 2800 animals.

The South Selkirks herd is one of 13 to 18 subpopulations in the Inland Rainforest that was probably a metapopulation at one time. These herds are increasingly fragmented consistent with habitat fragmentation.

Regarding animal transplants, the 60 caribou would be divided between the South Purcells herd first and the So Selkirks herd with each herd getting 20 on alternate years starting earliest in 2006, pending approval of First Nations in areas of source animals.

But the most important point in all of this is that 70% to 80% of the wood that is logged in the Inland Rainforest is exported to the U.S. The Mountain Caribou Project a collaborative effort of Canadian and U.S. conservation groups has just released a report that identifies the companies and the extent of the logging in these rare forests. It can be found along with other details about this unique animal and ecosystem at www.mountaincaribou.org. There are also links to much of the literature on mountain caribou.

Again, thanks very much for the posting and the attention to this imperiled animal and place.

Posted by: Joe Scott | Jul 14, 2005 12:05:20 PM

Thanks for commenting and thanks especially for pointing out that the Selkirk caribou are part of the imperriled mountain caribou ecotype. I should have mentioned that in my post.

But I do have a question for you. You write: "Incidentally, these lichens only start to appear in abundance in forests over 80 to 120 years old, not 50 as stated in the blog." If memory serves, I came up with the number 50 from conversations with a caribou biologist at Idaho's Department of Fish & Game. He led me to believe that the old-forest conditions that sustain the lichen could be replicated faster than 80 years in some instances. Is this incorrect? And, in any case, can you point me to some of the literature on the subject? (I ask because I'm still very much in the learning phase when it comes to caribou and I don't want to get my facts wrong.)

Thanks, Joe. I appreciate your insight.

Posted by: Eric de Place | Jul 18, 2005 2:04:56 PM