We've done a survey of caribou herds, and reindeer herds in the old world as well. Almost all of them are in decline, not only the boreal forest herds, the woodland caribou, but also the migratory herds. There are only a couple of herds in North America that are not declining, and one or two in Siberia. Almost all herds around the world are in decline. There are a number of reasons for that.
In the context of the boreal caribou, we understand how disturbance of habitat creates better habitat for moose and for deer. The result is an increase in wolf populations, and an increased wolf population results in greater depredation of caribou. This is called apparent competition, and has been demonstrated in Siberia as well as straight across Canada. So for woodland caribou, the industrial development associated with timber harvest and oil and gas development is having secondary consequences, not direct, but secondary.
In the north, alteration of climate is affecting the timing of the caribou's arrival on their calving grounds. The vegetation has already matured and gone past its most nutritious stage when the caribou arrive, so the nutritional status of many of the northern migratory herds has been affected as a consequence of climate change. The climate is changing more in the north than anywhere else on the planet.