Invasive alien species

What are alien species?

Alien species are animals and plants introduced by humans, sometimes unintentionally, in areas outside of their natural range. Many alien species found in the Northwest Territories (NWT) have been introduced from areas as far away as Europe and Asia. Alien species can also be referred to as exotics, non-indigenous, introduced and implanted.

Track where known alien plants can be found in the NWT using data the Giovernment of the Northwest Territories is sharing with the Alaska Exotic Plants Information Clearinghouse (AKEPIC) through the AKEPIC Data mapping portal.

Are all alien species harmful?

Generally, alien species do not pose a significant risk. Some alien species are present in the NWT but cause little harm to our ecosystem.Some are even beneficial to humans. We grow them in our gardens or raise them as food. Examples of these species include pin-cherry trees, Manitoba maples, carrots and potatoes.

Some alien species, however, can spread and invade habitats quickly. Alien species capable of causing significant harm to the environment, economy or society are called invasive alien species (IAS).

Why are invasive alien species harmful?

Invasive alien species are the second most important threat to native ecosystems, habitats and species after habitat change and degradation. Harm is usually caused after the species has invaded or spread to natural habitats or ecosystems. 

These invasive species compete with native species, change ecosystems and may result in the reduction or disappearance of native species. They can also harm the environment by making the landscape less attractive. For example, an invasive plant with large spines or toxins may stop animals or humans from using the area. Invasive insects can remove leaves making the trees in your yard less attractive. Examples of IAS introduced to the NWT include sweet clovers and amber-marked birch leaf miners.

Historically, it was assumed our northern climate would prevent most IAS from establishing themselves here. However, many northern communities have recently expressed concern over the potential effects of IAS in their communities.

How can we help prevent IAS from spreading?

Few IAS have entered the NWT. Elsewhere in Canada and the world, invasive plants and animals have become the second greatest threat to biodiversity after habitat loss.

Climate change and industrial development disturbs habitat. These and other factors can increase the chances of invasive plants and animals becoming established in the Northwest Territories. Help protect NWT habitats and keep invasive alien species out of the NWT. Learn more about invasive species and follow these steps to reduce their introduction and spread in the NWT:

Practice nature-friendly gardening and landscaping

Some attractive garden plants are invasive plants alien to the NWT. Others may carry unwanted insects that can damage our natural ecosystems. Consider using local plants instead of importing plants from south of the NWT. Dispose of yard waste away from adjacent natural areas to prevent the spread of alien plants.

Stop seeding invaders

Use weed-free soil, hay straw, mulch and certified seeds. Research the source and species list in your seed mix. Consider local northern seed sources for your reclamation work or not seeding at all.

Clean yourself at the door

Clean your vehicles, boats and outdoor equipment including outdoor footwear before entering the NWT or using these types of equipment.

Report out of place plants and/or insects

More alien species are being found in the NWT each year. This information is updated regularly thanks to studies and observations provided by NWT residents, as well as local and visiting experts.

Report large infestations of insects.  Learn how to identify invasive species and spread the word.  Get involved in the NWT Invasive Alien Species Project.

Animal species

If you find a species you think is alien to the NWT (bird, mammal, fish) contact local Environment and Natural Resources office and send an email with a photo, if possible, to

Plants and insects

To identify plants or insects, take detail notes and a photo of the species or collect only one plant and email the details to or