The migratory woodland caribou refers to two herds of Rangifer tarandus (known as caribou in North America) 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 (LRCH) and the George River caribou herd (GRCH) south of Ungava Bay. Rangifer tarandus caribou is further divided into three ecotypes: the migratory barren-ground ecotype, the mountain ecotype or woodland (montane) and the forest-dwelling ecotype (boreal woodland caribou). According to researchers,Mallory FF, Hillis TL (1998) Demographic characteristics of circumpolar caribou populations: ecotypes, ecological constraints/releases, and population dynamics. Rangifer Special Issue 10: 9-60. 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 (also known as George River hamlet). 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 population), 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 (COSEWIC), 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 (Rangifer tarandus), 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 (boreal woodland caribou). 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 (reindeer or caribou) 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 (1961), R. t. caboti (the Labrador caribou), R. t. osborni (Osborn's caribou (from British Columbia)) and R. t. terraenovae (the Newfoundland caribou) 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.The Integrated Taxonomic Information System list Wilson and Geist on their experts panel.
Geist (2007) 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..."[U]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 Harding LE (2022) Available names for Rangifer (Mammalia, Artiodactyla, Cervidae) species and subspecies. ZooKeys 1119: 117-151. doi:10.3897/zookeys.1119.80233. resurrects woodland caribou as Rangifer caribou, Arctic caribou as Rangifer arcticus, and Greenland caibou as Rangifer groenlandicus. The reasons for this are that (1) Greenland caribou are the most genetically divergent of all caribou and reindeer, with an average microsatellite genetic difference (Fixation Index) of FST = 44% from all others,Yannic G, Pellissier L, Ortego J, Lecomte N, Couturier S, Cuyler C, Dussault C, Hundertmark KJ, Irvine RJ, Jenkins DA, Kolpashikov L, Mager K, Musiani M, Parker KL, Røed KH, Sipko T, Þórisson SG, V.Weckworth B, Guisan A, Bernatchez L, Côté SD (2013) Genetic diversity in caribou linked to past and future climate change. Nature Climate Change 4: 132-137. doi:10.1038/NCLIMATE2074. justifying species status as originally named, Rangifer groenlandicus; it also has morphological and behavioral differences from barren-ground caribou (for example, they are "mixed migrators" (some migrate short distances and some do not,Raundrup K (2018) Movement patterns and resource selection - insights from West Greenland caribou. PhD Thesis, Denmark: Aarhus University, 115 pp. and they lack the aggregated rutting and post-calving and synchronized calving of barren-ground caribou);Poole KG, Cuyler C, Nymand J (2013) Evaluation of caribou Rangifer tarandus groenlandicus survey methodology in West Greenland. Wildlife Biology 19: 225-239. (2) the woodland caribou lineage diverged from other caribou in mid-Pleistocene, 300,000 to 357,000 years ago,Horn R, Marques AJD, Manseau M, Golding B, Klütsch CFC, Abraham K, Wilson PJ (2018) Parallel evolution of site-specific changes in divergent caribou lineages. Ecology and Evolution 8: 6053-6064. doi:10.1002/ece3.4154. not during the last glacial maximum (LGM: 23,000 to 19,000 years ago) as previously assumed and more likely descended from an earlier North American forest reindeer species such as Torontoceros [Rangifer] hypogaeus, Croitor R (2022) Paleobiogeography of Crown Deer. Earth 3: 1138-1160. (meaning that it cannot be the same species as barren-ground caribou because they do not share a direct common ancestor) and it has a different mating system (harem defense and dispersed calving vs. individual mate-tending, aggregated rutting and post-calving and synchronized calving of barren-ground caribou, resulting in antler architecture designed for combat rather than for displayButler HE (1986) Mating strategies of woodland caribou: Rangifer tarandus caribou. Doctoral thesis, Calgary, Alberta: University of Calgary, 565 pp.Geist V (1998) Deer of the world: their evolution, behavior, and ecology. Stackpole Books, Mechanicsburg, Pennsylvania, 421 pp.); these differences and its genetic distance from other caribou justify return to species status, R. caribou; (3) the above resulted in Arctic caribou reverting to the name given by Richardson (1829):Richardson J (1829) Fauna boreali-americana; or, the zoology of the northern parts of British America; containing descriptions of the objects of natural history collected on the late northern land expeditions, under command of Captain Sir John Franklin, R.N. Vol. 1 Quadrupeds, John Murray, London, U.K., 300 pp. Rangifer arcticus, representing a Beringian-Eurasian lineage (BEL); (4) 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, 2018Croitor R (2018) Plio-Pleistocene deer of Western Palearctic: taxonomy, systematics, phylogeny. Institute of Zoology of the Academy of Sciences of Moldova, Chișinău, 142 pp.—requiring their former namesMurie OJ (1935) Alaska-Yukon caribou. Vol. 54, United States Department of Agriculture Bureau of Biological Survey, Washington D.C., 93 pp.Anderson RM (1946) Catalogue of Canadian Recent mammals. National Museum of Canada Bulletin No. 102, Biological Series 31, Ottawa, Ontario, 238 pp. 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, 1914Allen GM (1914) The barren-ground caribou of Labrador. Proceedings of the New England Zoölogical Club 4: 103-107. 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 (Rangifer tarandus caribou) in 1961. Banfield classified the caribou of Ungava as woodland caribou (R. t. 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 (south of 55°N) to those farther north, the migratory ecotype Leaf River caribou herd (LRH) and the George River caribou herd (GRCH). In southern Ungava caribou females disperse from other females to avoid predators.