One of the most significant
threats to the unique biodiversity of these
islands is the introduction of non-native species.
Also called exotics, any species
not naturally found in an environment exists
without natural predators and can easily disrupt
the ecosystem. On the Queen Charlotte Islands,
11 species of land mammals and approximately
25% of plants now present are not indigenous.
Deer, introduced around 1800
as a food source for European immigrants to
the islands, have flourished in the absence
of predators, and now number more than 60,000.
The browsing deer totally clear the forest understory
of new shoots and eat the berries that would
normally be available for the bears, not only
taking the traditional food of another species,
but also inhibiting the forest's ability
to replenish itself.
When the boon in raccoon fur
did not occur, raccoons, introduced to the islands
to improve fur trapping, flourished in the food
abundant environment of Haida Gwaii. Their major
prey is the seabirds and their eggs, burrow
nesters being particularly vulnerable as their
eggs are so accessible.
Rats that came to the Queen
Charlottes by accident, in the holds of ships
arriving from the mainland, have invaded 17
islands in the archipelago and have threatened
or eliminated many of the seabird colonies.
Colony nesting is one of the characteristics
of seabirds, using the resources of the entire
colony for feeding and protection. Unfortunately,
it is this very trait which makes them such
easy prey for the rats.