What Happened to the Beverly Caribou Herd after 1994?

The Beverly herd was one of the first large migratory herds of barren-ground caribou (Rangifer tarandus groenlandicus) defined in northern Canada on the basis of annual return of breeding females to traditional calving grounds near Beverly Lake in Nunavut. In 1994, herd size was estimated at 276000 ± 106600 (SE) adult caribou, but monitoring was minimal from 1994 to 2007. The next calving ground survey in 2002 revealed that caribou densities had dropped by more than half since 1994; annual surveys following from 2007 to 2009 demonstrated an extreme decline in numbers of calving cows, and by 2011, no newborn calves were seen there. We examine two possible explanations for the declining use of the traditional Beverly calving grounds from 1994 until their abandonment by 2011. One explanation is that a true numerical decline in herd size occurred, driven in at least the later stages by low cow survival and poor calf productivity, which led the remaining Beverly cows to switch to the neighbouring Ahiak calving ground 250 km to the north in 2007-09 and join that herd. An alternative explanation is that the decline on the traditional Beverly calving grounds was largely due to a distributional shift to the north of the Beverly herd that may have begun in the mid-1990s. We suggest that the former explanation is the more likely and that the Beverly herd no longer exists as a distinct herd. We acknowledge that gaps in monitoring of Beverly and Ahiak caribou hamper definitive evaluation of the Beverly herd's fate. The large size sometimes achieved by barren-ground caribou herds is not a guarantee of persistence; monitoring shortfalls may hamper management actions to address declines. La harde de caribous de Beverly a été l'une des premières grandes hardes migratoires de caribous de la toundra (Rangifer tarandus groenlandicus) définies dans le nord du Canada en fonction du retour annuel des femelles reproductrices aux lieux de mise bas traditionnels situés près du lac Beverly, au Nunavut. En 1994, la taille de la harde était évaluée à 276000 ± 106600 (ES) caribous adultes, mais de 1994 à 2007, la surveillance a été minime. Le prochain recensement relatif aux mises bas a été réalisé en 2002, et celui-ci a révélé que les densités de caribous avaient chuté de plus de la moitié depuis 1994. De 2007 à 2009, des recensements annuels ont permis de constater le déclin prononcé du nombre de femelles en vêlage, si bien que vers 2011, on n'a aperçu aucun nouveau-né. Nous nous pen