West Greenland caribou explosion: What happened? What about the future?

Abstract

In West Greenland, the 1993 caribou (Rangifer tarandus groenlandicus) population size estimate was 7000 to 9000 animals. Eight years later in 2001, the estimate was ca. 140 000. Relatively rapid rise and fall cycles of abundance in West Greenland caribou have been noted since the 1700s. Caribou have no natural predators in West Greenland. Combined with their high fertility and recruitment, this suggests that overabundance might be their greatest threat to stability. The 2005 population surveys indicate poor recruitment in two major populations and decreasing abundance in one. Given stocking densities are three to six-times the value considered sustainable, we expect strong competition between individuals for available food resources. Although the management goal is sustainable harvest of natural resources, if populations continue at their current size or increase further, there is a clear risk of range overgrazing and trampling. Unsustainable range use may result in density-dependent forage limitation with subsequent relatively rapid population decline over a series of years, e.g. a decade. As in the past, populations are expected to recover, and if true to the past, recovery will take the better part of a century. Furthermore, the role of catastrophic weather events may be of major importance. Abrupt collapse could be precipitated by a disastrous single year event, e.g. thaw-freeze icing or deep snow, because possibilities for dispersal to new ranges are limited. Regardless of management initiatives taken now, population declines or crashes may be inevitable for some West Greenland herds in the foreseeable future, but accurate predictions about herd trends are impossible. To understand the potential impact of future developments, Greenland caribou and their range must be studied within the wider context of climate change.

Harvest impacts on caribou population dynamics in South West Greenland

“…2). This was seven times greater than the estimate of 4500 from 1996 (Ydemann & Pedersen, 1999), and caribou density was almost four times greater than a proposed target caribou density of 1.2 / km 2 (Kingsley & Cuyler, 2002;Cuyler et al, 2003Cuyler, 2007).…”

“…Following aerial surveys in the 1990s, the Greenland government's caribou managers thought that caribou populations through¬ out West Greenland were low in number, while the consensus from local hunters indi¬ cated substantially larger populations (Cuyler et al, , 2003Cuyler, 2007 (Fig. 2).…”

“…Following the large numbers of caribou, hunters observed habitat degradation; car¬ ibou-lichen heaths had become overgrazed where they had been deep and plentiful, and the once lush expanses of crowberries (Empetrum nigrum) were trampled (Cuyler et al, 2007). In the years following 2001, the government's caribou managers decided to attempt to reduce West Greenland caribou populations towards the target density.…”

“…N includes all age classes, and cv is given in %. (Cuyler et al, 2003Cuyler, 2007 (Table 3) was estimated from hunter reports. These reports were used to separate the har¬ vest into calves, juveniles and adults.…”

Transitions of social-ecological subsistence systems in the Arctic

“…Increasing populations of muskox and reindeer were followed by relaxed hunting regulations and increased catches (e.g. Cuyler 2007). The number of professional hunters and commercial use has decreased ( Figure 7); however, the number of non-professional hunters increased temporally, following changes in opportunities for reindeer hunting in the late 1990s and early 2000s (Rasmussen 2005).…”