Download Invasive species WS1

What are Alien Species? (Section One)
Alien species are plants, animals and microorganisms from one part of the world that are
transported beyond their natural range and are able to make themselves at home (become
established) in a new area. They are sometimes also called "exotic," "introduced," "nonnative," "non-indigenous" or "invasive" species.
Not all species that arrive in new places are able to make themselves at home and start reproducing and spreading. However, alien species can get established if given advantages
such as:
•
•
•
•
an agreeable climate;(not to hot, cold, wet or dry)
no or few natural predators, parasites or diseases;
an abundance of food plants or prey that are easy for them to find/catch.
are better able to find food, water and shelter (able to out-compete) than the animals and plants that already live there (natives).
You are already well acquainted with some alien, or non-native, species. For example the domestic cat is
thought to have originated in Africa. And the pigeon and the European Starling, birds commonly seen in
Canadian cities, both came from Europe. Even many of the foods you eat originated in other countries.
Potatoes came originally from the South American Andes, corn from Mexico, and wheat from Africa and
the Middle East.
There are also many examples of species from one part of Canada that have taken up residence in another. The familiar moose, for example, is native to most parts of the country, but is an introduced species
on the island of Newfoundland, as are the red squirrel and the snowshoe hare. The bullfrog is native to
some provinces, but is an alien species in British Columbia.
Many of Canada’s alien species are beneficial, but a great number are not. Sometimes the conditions are
right for alien species to become invasive—they move into new habitats and take over, their populations
sometimes expanding beyond control. The harm they cause to the environment, the economy, or human
health can be costly and sometimes irreversible.
How Do They Get Here? (Section Two)
Alien species come into Canada by any means of transport that moves them farther than they could move
on their own. Sometimes they are brought in on purpose, but often they arrive unintentionally. The natural area in which a species lives (range) has borders or barriers around it that prevent them
from moving into new areas. These borders usually consist of habitats where the species is
unable to survive and therefore they cannot “travel” through them. Humans have created
many opportunities for plants, animals and microorganisms to spread beyond these borders
- carrying them across oceans, mountains and deserts, and transferring them from one water body to another. In some cases, this has been done on purpose, though often with unexpected consequences, while in other cases it is unplanned.
Why Should We Be Concerned? (Section Three)
Most non-native species that make their way to Canada and British Columbia are either
beneficial or relatively harmless. However, all alien species must be treated with caution,
because it is difficult to predict which ones will cause problems over time. When an alien species enters an ecosystem, it can have an impact on the species that are present, on important habitats, or
even on the ecosystem itself. Concern arises when an alien species changes the system for the worse,
either by reducing or eliminating populations of native species, or by otherwise changing the way the ecosystem works.
These changes have made the invasion of alien species a major global problem. If organisms were not
able to move beyond their normal borders/boundaries, each part of the world would have its own special
kinds of plants, animals, and micro-organisms(biodiversity). But as species of plants and animals move
from one area of the world to another, sometimes destroying the native species, different places in the
world become more alike in their biology (there becomes less variety of plants and animals throughout
the world).
This process is undesirable because as it takes place, ecosystems often become less stable, and valuable biodiversity, (or variety of life), is lost. This variety of life is essential to the health of our planet; each
species performs a “job” that helps the world. The spread of invasive alien species, like habitat loss, is
considered one of the major threats to variety of live (biodiversity). Invasive alien species have destroyed
about 110 vertebrate species (animals with backbones) around the world. In Canada, about 5 percent of
mammal species and 27 percent of vascular plant species are aliens. The number of many other alien
species is not yet known.
Almost half the mammal species found on the island of Newfoundland and on the Queen Charlotte Islands, in British Columbia, are invasive aliens.
How do invasive species thrive? (Section Four)
Aliens that are successful invaders are species that have some advantage over native species. These
advantages are often made stronger when aliens move outside their natural environments, they are not
held back by natural predators, parasites, disease, or competition in the way that native species are. Here
are some Canadian examples of how alien species affect the species around them:
Competition: In many cases, invasive aliens out-compete native species for space, water, food, and other
essential resources. For example, non-native starlings eliminate native Canadian birds like bluebirds,
Red-headed Woodpeckers, and Tree Swallows by taking over their nesting sites. In addition, often aliens
reproduce more successfully than native species, quickly outnumbering the natives.
Predation: Some invasive aliens cause native populations to decline by being aggressive herbivores or
predators – eating the leaves off of trees and shrubs, overgrazing native plants or preying on native animals. Introduced rats and raccoons eat the eggs and nestlings of Ancient Murrelets and other seabirds
living on the coast of the Queen Charlotte Islands. By making this population smaller, the aliens may also
be affecting the vulnerable Peale’s Peregrine Falcon who use Ancient Murrelets as a food source.
How can you help? (Section Five)
•
•
•
•
•
Do not release alien plants or animals (including pets and live bait) into the wild.
Do not bring fruit, vegetables, plants, or animals with you across international borders. Be cautious about what you carry across interprovincial borders.
Before taking a recreational trip, inspect and clean fishing equipment, boats, trailers, recreational
vehicles, and other items that may harbor hitch-hiking invaders.
Do not transport over long distances firewood or other wood with bark attached.
Learn which plant species are invasive, and remove them from your garden. Take special care
with water garden plants, as many are invasive. If you are unsure about a new species, plant it
where you can easily control its spread, and remove it if necessary. Avoid planting alien species
next to, or within, natural areas, roadsides, or forested fence rows.
Science 7: Alien/Invasive Species W.S
Name:_______________________
1) Alien species are organisms that have been transported
beyond their ___________ (2 words: Section One)
2) Alien species are able to become _______ in a new area.
3) When an alien species becomes at home in a new area they
are able to ___________ and ___________.
4) What are two other names for alien species?
5) Native species of plants and animals are able to out
compete alien species for food, water, and shelter. (T of F)
6) Where do potatoes originally come from?
7) A species of amphibian that is alien to B.C.
8) An alien species is called an invasive species when they move
into a new habitat and ___________ (2 words)
9) Alien species move into new areas when they are moved ____
than they could move on their ____. (Section Two)
10) The natural area in which a species lives is called its ____.
11) The borders that prevent a species from “traveling” usually
consist of _____ in which they cannot _______.
12) Which species of animal is directly responsible for moving
plants and animals across borders and boundaries?
13) Most alien species coming into Canada are ___ .(Section Three)
14) Alien species are harmful when they reduce or _______
populations of ________ species and change the way an ecosystem
works.
15) The variety of life in an ecosystem can be summed up by this word.
16) Invasive alien species have destroyed about ____ species of
vertebrates.
17) Fifty percent of the mammals on these islands in B.C are alien
species.
18) Successful alien species have some kind of ___over native
species. (Section Four)
19) Starling out-compete native Canadian birds by taking over
their ____ (two words)
20) The population of Ancient Murrelets living on the Queen Charlotte
islands is decreasing due too these two alien species.
21) If you get tired of your pet the best thing you can do is release it into
the wild. (Section Five: T or F)
22) Transporting fire wood with the bark on can cause species to be
introduced to new ecosystems. (T or F)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22