There is some evidence to suggest that, on occasion, they also feed on small rodents such as lemmings, fish such as Arctic char and bird eggs.

[8] The Beverly herd (located primarily in Saskatchewan and the Northwest Territories, with portions in Nunavut, Manitoba and Alberta) and the Qamanirjuaq herd (located primarily in Manitoba and Nunavut, with portions in the southeastern NWT and northeastern Saskatchewan) fall under the auspices of the Beverly and Qamanirjuaq Caribou Management Board.

We want to...give everybody time to work together to come up with solutions for the short term and until the caribou populations recover.John Nagy, University of Alberta's wildlife biologist and researcher, argued that the Beverly herd was robust, not declining.

He based his findings on data collected from 510 barren-ground caribou tracked with satellite collars in the Northwest Territories and Nunavut from 1993 to 2009.

In 2004 the Canadian Government's Species at Risk (SARA) registry placed barren-ground caribou under the status of "special concern".

[25][26][27] Frozen feeding grounds during winter months results in greater energy expenditure as the caribou attempt to access the lichen locked beneath the ice.

The trophic mismatch, due to abnormal temperature variations linked to climate change, have resulted in malnutrition in their young, as well as reduced reproductive rates contributing to population decline.

[26][25][24] Warming weather conditions reduce ice thickness over rivers and lakes, making it difficult for caribou to cross.

[24][20][28] Unpredictable migration patterns also have negative impacts on Indigenous communities who depend on caribou as a source of income and food.

[21][20][28] Insect harassment force caribou to migrate to areas which may still be covered in snow or ice, thereby reducing access to food.

[26] Caribou give birth in early spring when insect populations are low, to enable sufficient rearing of healthy and strong calves.

[23] Early onset of spring temperatures in the Arctic further effect the phenology of the pregnancy time periods of barren-ground caribou.

[29] Rangifer originated Late Pliocene and diversified in the Early Pleistocene, a 2+ million-year period of multiple glacier advances and retreats.

Archaeologists distinguish “modern” tundra reindeer and barren-ground caribou from primitive forms — living and extinct — that did not have adaptations to extreme cold and to long-distance migration.

[30] They include a broad, high muzzle to increase the volume of the nasal cavity to warm and moisten the air before it enters the throat and lungs, bez tines set close to the brow tines, distinctive coat patterns, short legs and other adaptations for running long distances, and multiple behaviors suited to tundra, but not to forest (such as synchronized calving and aggregation during rutting and post-calving).

Conversely, Molecular data also revealed that the four western Canadian montane ecotypes are not woodland caribou as currently classified (in Canada): they share a common ancestor with modern barren-ground/tundra reindeer and caribou, but distantly, having diverged > 60,000 years ago[41] — before the modern barren-ground ecotype had evolved its cold- and darkness-adapted physiologies and mass-migration and aggregation behaviors, (see Reindeer: Evolution).

Before Banfield (1961),[42] taxonomists using cranial, dental and skeletal measurements had unequivocally allied these western montane ecotypes with barren-ground caribou, naming them (as in Osgood 1909[43] Murie, 1935[44] and Anderson 1946,[45] among others) R. a. stonei, R. a. montanus, R. a. fortidens and R. a. osborni, respectively, and this phylogeny was confirmed by genetic analysis.

Banfield (1961) had extended the tiny, pale granti (originally Rangifer granti Allen 1902[46]) of the west end of the Alaska Peninsula and nearby islands to all of Alaska and part of Yukon, including the Porcupine herd, which was originally described as R. ogilviensis (Millais 1915),[47] after the Ogilvie Mountains that form part of its winter range.

Subspecies in North America are, R. t. caboti, R. t. caribou, R. t. dawsoni, R. t. groenlandicus, R. t. osborni, R. t. pearyi, and R. t. terranovae; and in Eurasia, R. t. tarandus, R. t. buskensis (called R. t. valentinae in Europe), R. t. phylarchus, R. t. pearsoni, R. t. sibiricus and R. t. platyrhynchus.