| < Back | page 2 of 7 |
Next > |
Submodule 5: Invasive Animals
Pathways
Most animal introductions are human caused, and occur both deliberately and unintentionally. Some animals traveled to the U.S. as hitchhikers in shipping crates or ballast waters, some were introduced as food, and others were brought here to help control other invasive organisms. The sea lamprey (Petromyzon marinus), a predator of many native fishes, was aided in its invasion of the Great Lakes by the construction of the Welland Canal allowing it to bypass Niagara Falls. Animals have also expanded their native ranges because of man-made activities. For example, several prairie-dwelling animals extended their range to previously forested regions of the midwestern U.S.
Once an animal has been introduced to a region, it may greatly expand its range or it may remain close to the point of introduction. How it becomes established in its new habitat depends on many factors including its adaptability and the similarity between the new range and the original habitat. For example, the house sparrow (Passer domesticus) has spread to inhabit most of the U.S. mainland since its introduction, whereas the European tree sparrow remains in a fairly small area in the middle of the U.S. mainland.
| < Back | page 2 of 7 |
Next > |