The other day I saw about half a dozen birds sitting in the branches of an apple tree outside my front window. I’d never seen them before, and haven’t seen them since. They looked like some sort of dove. Probably just passing through. I’ll have to look them up in one of my bird books.
Wildlife species have been dispersing and re-dispersing themselves throughout the world for millions of years. The only real difference between so-called “historical” introduction of species, and those which have taken place in the past couple of hundred years, is the rate and scale with which they have taken place. So when wildlife biologists and other experts use words like alien, exotic and invasive to describe plant and animal species that have been introduced into new or “non-indigenous” environments, it is as much a question of semantics as anything else.
Before human travel became widespread, plants and animals arrived on foreign shores mostly by chance. In some instances they swam across oceans, migrated across continents, drifted on air and water currents or hitched rides with other travellers.
Here is where semantics come in. Plant and animal species that arrive and establish themselves in an ecosystem where they did not evolve are described as “alien.” Once established beyond the initial point of introduction, they are then considered “naturalized” components of their new environment. An alien species is considered “invasive” when and if it displaces native species. The invasive species tend to reproduce quickly, spread rapidly and compete aggressively with indigenous species, in large part, because there are usually few or no indigenous species that can or will predate on the new arrivals.
However, these so-called alien/invasive species did not actually sit down and plot out any sort of intentional invasion of their new home and surroundings. They simply, one day, found themselves there and then proceeded to go about the mundane business of surviving and reproducing.
Words like ‘alien’ and ‘invasive,’ not to mention ‘naturalized,’ ‘indigenous’ and ‘non-indigenous’ are human words used to describe processes which affect human habitat and environments – and human economies.
Not too long ago the Ministry of Forests, Lands and Natural Resource Operations proposed a culling of wolves in several regions of the province. At the time, the government said the proposed changes (to legislation) were meant to help cattlemen protect their herds from predation by wolves.
The question here is just who is the invasive species?
The cattle ranchers, who have expanded their grazing territory into timbered Crown lands, simply wanted to protect their profits and were able to put pressure on the provincial government to introduce the cull. Once again, the reason was purely political.
Expecting wolves not to predate on cattle grazing in their backyard is sort of like cooking up a pot roast for Sunday supper, setting it on the kitchen table to cool, telling the dog not to touch it and then leaving the room.
What you have with both the wolf cull and the pot roast situations is a lack of reasoning coupled with not enough understanding, combined with a degree of stupidity, added to a natural instinct to eat food that’s sitting right there in front of you – all with various amounts of self-interest and self-preservation mixed into the equation.
It’s a good thing we’ve got politicians to figure these sort of situation out.