Migratory woodland caribou


The migratory woodland caribou refers to two herds of Rangifer tarandus that are included in the migratory woodland ecotype of the subspecies Rangifer tarandus caribou or woodland caribou that live in Nunavik, Quebec, and Labrador: the Leaf River caribou herd and the George River caribou herd south of Ungava Bay. Rangifer tarandus caribou is further divided into three ecotypes: the migratory barren-ground ecotype, the mountain ecotype or woodland and the forest-dwelling ecotype. According to researchers, the "George River herd which morphologically and genetically belong to the woodland caribou subspecies, at one time represented the largest caribou herd in the world and migrating thousands of kilometers from boreal forest to open tundra, where most females calve within a three-week period. This behaviour is more like barren-ground caribou subspecies." They argued that "understanding ecotype in relation to existing ecological constraints and releases may be more important than the taxonomic relationships between populations." The migratory George River caribou herd travel thousands of kilometres moving from wintering grounds to calving grounds near the Inuit hamlet of Kangiqsualujjuaq, Nunavik. In Nunavik and Labrador, the caribou population varies considerably with their numbers peaking in the later decades of each of the 18th, 19th and 20th centuries. In 1984, about 10,000 caribou of the George River herd drowned during their bi-annual crossing of the Caniapiscau River during the James Bay Hydro Project flooding operation. The most recent decline at the turn of the 20th century caused much hardship for the Inuit and Cree communities of Nunavik, who hunt them for subsistence.
While the woodland caribou, Rangifer tarandus caribou, boreal woodland caribou or boreal caribou, which is mainly sedentary, was assessed in May 2002 as threatened by the Committee on the Status of Endangered Wildlife in Canada, not all herds and populations are endangered. For example, the Gros Morne National Park sedentary herd in insular Newfoundland is not endangered.

Ecotypes

Subspecies and ecotypes

The subspecies of caribou, a medium-sized ungulate, inhabit boreal, montane and Arctic environments and "exhibit tremendous variation in ecology, genetics, behaviour and morphology." Most are found in Canada. Current classifications of Rangifer tarandus, either with prevailing taxonomy on subspecies, designations based on ecotypes, or natural population groupings, fail to capture "the variability of caribou across their range in Canada" needed for effective species conservation and management. "Across the range of a species, individuals may display considerable morphological, genetic, and behavioural variability reflective of both plasticity and adaptation to local environments."
In eastern North America caribou are classified into three ecotypes – "the mountain caribou which is found south of the St. Lawrence River, the barren-ground caribou which calves in the tundra, and in between, the forest-dwelling ecotype which lives all year long in the boreal forest."
In west-central Alberta there are two ecotypes – boreal and mountain.
In Québec there are three ecotypes with specific habitats and behaviour – the migratory barren-ground ecotype, the mountain ecotype and the forest-dwelling ecotype. In British Columbia caribou are classified into three ecotypes – mountain, northern and boreal. In Ontario caribou are classified into two ecotypes – forest-dwelling woodland caribou and forest-tundra woodland caribou. In Newfoundland and Labrador, woodland caribou are classified as part of the boreal population of caribou, which is subdivided into two ecotypes: the migratory forest-tundra and the sedentary forest-dwelling ecotype.

Taxonomy

The species taxonomic name Rangifer tarandus was defined by Carl Linnaeus in 1758. The subspecies taxonomic name, Rangifer tarandus caribou was defined by Gmelin in 1788.
According to the then-Canadian Wildlife Service Chief Mammalogist, Frank Banfield, in his often-cited A Revision of the Reindeer and Caribou, Genus Rangifer, R. t. caboti, R. t. osborni and R. t. terraenovae were considered invalid and included in R. t. caribou.
Some recent authorities have considered them all valid, even suggesting that they are quite distinct. In their book entitled Mammal Species of the World, American zoologist Don E. Wilson and DeeAnn Reeder agree with Valerius Geist, specialist on large North American mammals, that this range actually includes several subspecies.
Geist argued that the "true woodland caribou, the uniformly dark, small-manned type with the frontally emphasized, flat-beamed antlers", which is "scattered thinly along the southern rim of North American caribou distribution" has been incorrectly classified. He affirms that the "true woodland caribou is very rare, in very great difficulties and requires the most urgent of attention."
In 2005, an analysis of mtDNA found differences between the caribou from Newfoundland, Labrador, southwestern Canada and southeastern Canada, but maintained all in R. t caribou.
Mallory and Hillis argued that, "Although the taxonomic designations reflect evolutionary events, they do not appear to reflect current ecological conditions. In numerous instances, populations of the same subspecies have evolved different demographic and behavioural adaptations, while populations from separate subspecies have evolved similar demographic and behavioural patterns..."nderstanding ecotype in relation to existing ecological constraints and releases may be more important than the taxonomic relationships between populations."
A recent taxonomic revision of the genus Rangifer resurrects woodland caribou as Rangifer caribou, Arctic caribou as Rangifer arcticus, and Greenland caibou as Rangifer groenlandicus. The reasons for this are that Greenland caribou are the most genetically divergent of all caribou and reindeer, with an average microsatellite genetic difference of FST  = 44% from all others, justifying species status as originally named, Rangifer groenlandicus; it also has morphological and behavioral differences from barren-ground caribou ; the woodland caribou lineage diverged from other caribou in mid-Pleistocene, 300,000 to 357,000 years ago, not during the last glacial maximum as previously assumed and more likely descended from an earlier North American forest reindeer species such as Torontoceros hypogaeus, and it has a different mating system ; these differences and its genetic distance from other caribou justify return to species status, R. caribou; the above resulted in Arctic caribou reverting to the name given by Richardson : Rangifer arcticus, representing a Beringian-Eurasian lineage ; Genetic analysis confirmed earlier assignments based on morphological measurements that placed the four western montane ecotypes in the BEL lineage, but distantly, having diverged > 60,000 years ago—before the modern ecotypes had evolved their cold- and darkness-adapted physiologies and mass-migration and aggregation behaviors (see Croitor, 2018—requiring their former names to be restored: Selkirk mountain caribou, R. a. montanus, Rocky Mountain caribou, R. a. fortidens, Osborn's caribou, R. a. osborni and Stone's caribou, R. a. stonei. As years of molecular analyses had shown the Eastern Migratory population to be of woodland caribou ancestry, albeit with ancient introgression from barren-ground caribou, their name R. caribou caboti Allen, 1914 was restored. See Reindeer: Evolution and Reindeer: Taxonomy for more detail.

Range and population changes

Québec

All caribou of the province of Québec were assigned to the same subspecies in 1961. Banfield classified the caribou of Ungava as woodland caribou based on skull measurements.
In Québec there are three ecotypes with specific habitats and behaviour. Bergerud, et al.; compared the sedentary ecotype caribou in southern Ungava to those farther north, the migratory ecotype Leaf River caribou herd and the George River caribou herd. In southern Ungava caribou females disperse from other females to avoid predators.
  1. The barren-ground ecotype, the only migratory form, is found north of the 52nd parallel. This ecotype currently occupies 255,000 km2 in fall and winter, mainly in the ecological subzones of the forest-tundra and the taiga. The barren-ground caribou was characterized by a very low abundance from the end of the 19th century until the mid-1950s, but increased markedly thereafter, reaching over a million individuals at the beginning of the 1990s.
  2. The mountain ecotype have been identified in the southeastern and, possibly, in the northeastern parts of the province. The latter mountain population is virtually unknown. The southeastern population is sedentary and uses mainly the boreal forest. This population has decreased over the last century and currently numbers only 140 individuals.
  3. The forest-dwelling ecotype is found discontinuously, mainly between the 49th and 55th parallels. Its current distribution covers 235,000 km2, mainly east of the 72nd meridian. This sedentary ecotype is found almost exclusively in the boreal forest, principally in areas with long forest fire cycles. Its abundance has also decreased over the years. Large forest-dwelling populations still persisted during the 1950s and 1960s, but they apparently disappeared. The current abundance is not known precisely, but based on density estimates and considering the current distribution, it probably does not exceed 3,000 individuals. Current data are insufficient to identify precisely the causes of the population decline, although hunting seems to be an important proximal cause.