Caribou, a species of deer closely related to the reindeer, were once a fixture of Maine’s northern wilderness. Maine represented the southernmost boundary of the species’ historical range within the contiguous United States. Their disappearance from the landscape is an example of extirpation, where a species vanishes completely from a specific geographic area. The last wild herds succumbed to a combination of human pressures and ecological changes around the turn of the 20th century.
The Historical Presence of Woodland Caribou in Maine
The species that once inhabited the state was the Woodland Caribou, scientifically known as Rangifer tarandus caribou. These animals were notably larger than their Arctic cousins, with mature bulls occasionally weighing up to 700 pounds. They were well-adapted to the deep snow conditions of the boreal forests, possessing large, concave hooves that functioned effectively as snowshoes and for scraping away snow to find food.
Historically, caribou were widespread across the northern half of Maine, with strong populations in the Allagash Wilderness Waterway and the high-elevation areas around Mount Katahdin. Reports from the mid-19th century indicate caribou herds would gather in large numbers on the frozen surfaces of the state’s big lakes during winter.
The decline of the native population began in the late 1800s, marking a swift end to their long tenure in the region. While some records suggest the last individual was shot on Mount Katahdin’s Tablelands in 1908, small groups persisted slightly longer. A game warden documented a small herd along the St. John River’s tributary, Burntland Brook, as late as 1911, with unconfirmed sightings near the Katahdin region continuing until 1914.
Ecological Drivers of Caribou Extirpation
The initial and most immediate cause of the rapid decline was unregulated market hunting in the 19th century. Caribou meat was highly valued and in high demand, leading to the wholesale slaughter of herds by unscrupulous hunters who shipped the meat to distant cities.
The caribou’s natural defensive behavior made them particularly vulnerable to these hunters; when fired upon, the confused animals would often circle instead of dispersing, allowing entire herds to be devastated. The state ultimately outlawed caribou hunting in 1899, but this conservation measure came too late to save the few animals remaining.
Simultaneously, extensive logging and habitat fragmentation across the state destroyed the specific environment the caribou required. Woodland Caribou rely heavily on ground and arboreal lichens for sustenance, which grow predominantly in mature, old-growth coniferous forests. The widespread clear-cutting eliminated their primary food source, a habitat change that takes 80 to 150 years to naturally reverse.
A third factor was the rise of “apparent competition” driven by the white-tailed deer population. Logging practices led to a surge in deer numbers, as they thrive in the younger forests that replaced the old growth. These deer introduced the meningeal worm, Parelaphostrongylus tenuis, a parasitic roundworm harmless to deer but deadly to other cervids like caribou. When caribou ingest intermediate hosts, the parasite migrates to the brain and spinal cord, causing neurological damage and death.
Current Status and Reintroduction Feasibility
The Woodland Caribou is currently considered extirpated from Maine. The last definitive records place their presence in the state at over a century ago, leading to discussions and attempts at restoration. These efforts, however, have been met with significant challenges.
The state has made two major attempts to reintroduce caribou, both using stock from Newfoundland. The first effort occurred in 1963, when two dozen caribou were released in Baxter State Park, but they dispersed or died within a few years. A larger, more coordinated attempt took place in the late 1980s, which included a captive breeding program at the University of Maine in Orono.
This second attempt also failed after the caribou were released into the wild. Many of the newborns and adults succumbed to the brainworm parasite, even after being treated with the antiparasitic drug ivermectin while in captivity. Additionally, predation by black bears was a major factor, with nearly half of the first released cohort being killed by bears.
Ecological changes in the Maine woods remain the primary barrier to successful reintroduction today. The high density of white-tailed deer ensures the widespread presence of the fatal brainworm across former caribou habitat. Furthermore, the lack of extensive, mature boreal forest means there is insufficient lichen for a self-sustaining population. The current consensus among wildlife biologists is that the ecological conditions are stacked against the caribou’s return.