Dolphin and Union Caribou Herd Status and Trend
Keywords:caribou, Rangifer, migration, population size estimate, population trends, Dolphin and Union herd, Canada, Nunavut, Northwest Territories
The Dolphin and Union caribou herd (Rangifer tarandus groenlandicus) is of great importance for Inuit subsistence and cultural needs. This herd is somewhat particular in that it relies on the seasonal connectivity of the sea ice between Victoria Island and the mainland to undertake its fall and spring migrations to and from its wintering ground on the mainland. While the herd may have numbered in the order of 100 000 animals in the past, it experienced a dramatic decline in the early 1900s and stopped its migration to the mainland. It resumed its migration only as it started to increase during the 1980s and 1990s, and in October 1997, the caribou gathered on the southern coast (prior to crossing to the mainland) were estimated to number 27 948 ± 3367 SE. In October 2007, using the same method and covering approximately the same area as during the 1997 survey, we estimated 21 753 ± 2343 SE caribou within our study area. The method used in 1997 and 2007 assumes that most of the herd is located within a narrow strip along the southern coast of Victoria Island, but also acknowledges that some caribou are outside that area. Therefore, we undertook a correction of both 1997 and 2007 estimates for the Dolphin and Union caribou herd based on available data from radio-tracking of female caribou. The corrected estimate for the Dolphin and Union caribou herd in 2007 was 27 787 ± 3613 SE. Both the study area estimates and the corrected herd estimates for 1997 and 2007 indicate that the herd trend in the intervening decade was at best stable.