Mammals of Salt Spring Island
Southwestern British Columbia was once home to mammoths, mastodons, muskoxen, and bison, but these animals were displaced during the Fraser glaciation, which peaked some 15,000 years ago. As the ice retreated, the land was repopulated by wildlife immigrating from southern latitudes and from local ice-free refugia. Bison bones from Saanich on Vancouver Island and from Orcas Island date from the early postglacial period, when tundra parkland may have been prevalent. As the climate warmed, coniferous forests became dominant, suitable for a mammal fauna similar to that of today.
Presently, Salt Spring Island and Vancouver Island share many mammal species in common, and it is likely that there were episodes of postglacial dispersal between the two islands via temporary bridges of ice, sea bed, or glacial outwash plains. Vancouver Island is home to at least eight mammal species not known from Salt Spring, including marten, wolverine, and marmot. The lower number of species on Salt Spring is attributable to the smaller area of the island. Biodiversity typically declines with island size because small populations are more vulnerable to extinction.
Recently, significant changes on Salt Spring resulting from forestry, farming, and increasing settlement have altered the ecology of the island. Several hundred cattle were present by the early 1860s, when wolf poisoning began, and it is likely that wolves were gone by the 1880s. The last resident elk appears to have been shot in the 1860s. Alien species have been introduced and feral livestock have spread. Herbivores have thrived with the elimination of wolves and the decline of mountain lions.
Invasive Species and Environmental Protection
Several mammal species on Salt Spring are not native to British Columbia, and may cause significant environmental harm. These are the Brown Rat, Black Rat, Coypu, and rabbits. Rabbits are well established and damage to native flora may become extensive, as has been observed on other islands, such as Smith Island and San Juan Island.
Pets and livestock should not be released into the wild. Cats will prey upon native wildlife such as songbirds, bats, and reptiles, and may spread diseases and parasites. Feral sheep and goats negatively impact wild plant populations and diminish biodiversity, with a cascading effect on other animals, such as butterflies.
Listed below are mammal species that have been observed on Salt Spring Island or in nearby waters. Species represented by museum specimens from Salt Spring are marked with an asterisk (*). Some animals are now rare (black bear, mountain lion), likely transients, swimming to Salt Spring from afar. Elk and wolf were extirpated in the 1800’s, although two bull elk were recorded on Salt Spring in the 1950’s, one of which was observed swimming Sansum Narrows, between Salt Spring and Vancouver Island. A wolf was reportedly shot in 1930. The number of bat species may be conservative; ongoing inventory may add new records. Occasionally sea otters are sighted, but these are strays from the outer coast, and this species is absent from the local archaeological record.
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And for more information on the natural history of mammals, enter a species name (for example, mink) into the Smithsonian North American Mammals page.