Dolphin-Union caribou

Dolphin and Union Caribou, Dolphin and Union caribou herd, Dolphin-Union, locally known as Island Caribou, are a migratory population of barren-ground caribou, Rangifer tarandus groenlandicus, that occupy Victoria Island in the Canadian Arctic Archipelago and the nearby mainland. They are endemic to Canada. They migrate across the Dolphin and Union Strait from their summer grazing on Victoria Island to their winter grazing area on the Nunavut-Northwest Territories mainland in Canada. It is unusual for North American caribou to seasonally cross sea ice and the only other caribou to do so are the Peary caribou who are smaller in size and population. They were listed as Special Concern by Committee on the Status of Endangered Wildlife in Canada since May 2004.

Morphology

Pelage

The pelage of the Dolphin and Union Caribou is white in winter and slate-grey with white legs and under-parts in summer like the Peary caribou. The Dolphin and Union Caribou are slightly darker.

Antlers

Dolphin and Union Caribou have the characteristic light slate-grey antler velvet of Peary caribou as opposed to the dark chocolate brown antler velvet of other barren-ground caribou and woodland caribou.

Genetics

Manning had erroneously categorized the Dolphin and Union Caribou as Peary caribou and the species was originally listed by COSEWIC until 2004. By more recent studies had clearly shown that Dolphin and Union Caribou are genetically distinct from both Peary and barren-ground caribou.

Population

"About 27,000 Dolphin-Union Caribou occupy areas in Nunavut and the NWT. These caribou were at very low densities during the mid-20th century and only started recovering about 30 years ago. The main distribution during the calving and fall seasons is on Victoria Island and since the 1960s Dolphin-Union Caribou resumed their migration to winter on the Nunavut-NWT mainland. The population is considered stable at best, or slightly declining."

Conservation

In 2004 COSEWIC listed the Dolphin and Union Caribou population as Special Concern.

Habitat

In summer the herd occupies Victoria Island where it is often on "beach ridges and river valley slopes." While normally they winter in the Bathurst Inlet area of Nunavut, the herd has migrated as far as Tuktut Nogait National Park in the west, following the shoreline in search of windswept areas where the snow cover is cleared making it easier for them to graze.

Co-management

By 2012 the Nunavut Wildlife Management Board and the Kitikmeot Hunters and Trappers Association and the Wildlife Advisory Management Council were preparing co-management plans for the conservation of the Dolphin and Union Caribou population.
Potential threats to survival of the Dolphin-Union Caribou

There are a number of concerns including potential over-harvesting by hunting, "over-grazing in areas where caribou wait before migrating to the mainland for the winter"; "local knowledge has demonstrated an increase of predators across summer ranges"; "an unknown number of caribou die every fall breaking through the ice crossing to the mainland"; "changes to sea ice freeze-up and break-up due to climate change could threaten migration; and "Increased ship traffic through Dolphin and Union Strait may affect ice formation and caribou migration."