Consequences

Introduced species issue - Deer - Raccoon - Beaver - Squirrel - Rats - Plants - Others -
An overview of consequences

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An overview of consequences

The islands of Haida Gwaii / Queen Charlottes support a unique population of flora and fauna with many sub-species that are considered unique to the islands. Haida Gwaii has more unique sub-species than any other equal sized area in Canada.

Overall there are relatively few native terrestrial animals on Haida Gwaii compared to the nearby mainland. The Islands have 11 native mammals and 1 toad while the mainland coast has 31 native mammals and many herptiles.

There are 16 alien animal species on Haida Gwaii, 14 mammals and 2 frogs.

Islands like Haida Gwaii have fewer species than the mainland and are more vulnerable to the effects of introduced species.

Mainland species are often successful when introduced to islands. In the absence of predators or competition, their numbers can increase unchecked. They threaten native species, cause environmental degradation and can cause extinction. There is concern that unique species on Haida Gwaii are at risk and some may even be lost.

For most introductions to the Islands, little thought was given to the consequences. People were just bringing familiar plants and animals for gardens, sport, trapping or food. Many introductions were done accidentally.
In most cases introduced species appear to be harmless, it is only over time when they spread that the impacts become evident.

NATIVE SPECIES	INTRODUCED SPECIES (earliest known date of introduction)
Black bear	Sitka black-tailed deer (1878)
Dawsons' caribou (extinct)	European red deer (1919) (extinct)
River otter	Rocky mountain elk (1929)
Pine marten	Raccoon (1940's)
Haida ermine	Beaver (1936)
Deer mouse	Muskrat (1924)
Dusky shrew	Red squirrel (1947)
Silver haired bat	Black rat (1919)
California myotis (bat)	Norway rat (1922)
Keen's myotis (bat)	House mouse (1901)
Little brown bat	Feral cattle (1893)
	Feral goats (1976) (extinct)
	Feral dogs - no date
	Feral cats - no date
	Feral rabbits (1884)

What is special about the native animals of Haida Gwaii?

The black bears of Haida Gwaii are a sub-species of the North American black bear. They are the largest on the continent and are thought to have survived in the refugia during the last glaciation. They have a heavier and differently shaped jaw, believed to have evolved from eating shellfish.

Bears compete for many food plants with introduced species; grasses and sedges, skunk cabbage and crabapple to name a few. Little is known at this time about the impact this competition has on bear populations.

The black bears, Taan, are highly respected in Haida culture. The Council of the Haida Nation has imposed a moratorium on the recreational hunting of bears on Haida Gwaii.

The Haida ermine is possibly the rarest mammal in BC. The differences in colouring and the form of its skull may put it as a separate species from those of the mainland.
It too, was thought to have survived the last glaciation. Populations are now much reduced possibly from cascading effects of introduced species.

introduced squirrels are a food for pine marten,
Pine marten numbers increased and possibly competed the Haida ermine for food
Deer browsing might also have indirectly affected Hermine food.

Haida Gwaii has some of BC's most extensive seabird nesting areas and is internationally recognized for its seabird populations.
The storm petrel, pictured here, has several nesting colonies on the Islands.
BC has half the worlds breeding population of Ancient murrelets.
Naikoon Park has BC's largest breeding population of Sandhill cranes.
Introduced species are having significant impacts- see the pages on rats and raccoons for more info.

The Dawson's caribou, now extinct, was a unique sub-species to the Islands.

It is thought that the introduction of deer may have brought disease to the caribou, but they are believed to have been already on the verge of extinction. The last few animals found were malnourished and stunted.

The effects of deer, beaver and raccoon on Haida Gwaii are considered the most serious and widespread.
Rats, muskrats and feral cattle have had significant effects in localized areas.

Feral animals are domestic animals that have gone wild. Some of these are having adverse impacts on the environment of Haida Gwaii. Some of the more obvious are feral cattle impacting plants and trampling soft soils, cats preying on seabird colonies and rabbits overbrowsing vegetation. The list also includes pigs, goats, dogs and mink.

Introduced species management on Haida Gwaii is tied to forestry, hunting, recreation, agriculture and human habitation.

Introduced species could be allowed to find their natural level in the ecoystems, but this would reduce biodiversity and may drive some species to extinction.

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