Care for the land: Parks Canada works to control invasive alien species

A love for native biodiversity

Parks Canada protects some of the most treasured places in the country. From old growth forests, to prairie grasslands, to mountain ecosystems—these protected areas are home to an incredible diversity of native wildlife. Yet the introduction of invasive alien species (IAS) is impacting these special places.

A forest with many trees and ferns.
Eastern Hemlock forest of Kejimkujik National Park and National Historic Site in Nova Scotia
A close up of a medium sized brown bird standing in golden coloured grass.
An endangered Greater Sage-Grouse in Grasslands National Park in Saskatchewan
Wildflowers in Waterton Lakes National Park in Alberta

Parks Canada works with many groups to protect threatened ecosystems and wildlife from IAS. Together, we use leading-edge techniques to prevent and control IAS. We also restore areas damaged by IAS—and help native species recover.

Invasive alien species

Invasive alien species are insects, plants, animals, and fungi that were introduced to areas outside of their natural range by human activity, either by accident or on purpose. Found in both terrestrial and aquatic ecosystems, they are the second largest threat to biodiversity in the world next to habitat loss.

A close up of an evergreen tree branch with white clusters covering the stem.
Hemlock Woolly Adelgid, an aphid-like forest pest, infesting the branch of the tree
A close up of flower buds.
Spotted Knapweed is invading native prairie grasses
A brown wild pig walks toward the camera on dry patchy ground.
Invasive wild pigs are causing widespread damage in Western Canada

Once an introduced species is established, IAS can continue to spread further in its new environment. The introduction of IAS can harm ecosystems, species, and people in many ways. They can have severe and often irreversible impacts to native ecosystems.

Introductions of IAS threaten native wildlife by:

  • increasing predation on native species
  • reducing the health of native species
  • altering habitat
  • increasing competition for resources
  • breeding with native species causing hybridization
  • compounding threats to species at risk
A close up of a tree trunk. Its bark is missing. Swirly engravings can be seen on the exposed trunk.
The markings that invasive Emerald Ash Borer larva leave on Ash trees
The bank of a pebbly shore is almost fully covered in dense green shrubs with yellow flowers.
Invasive Scotch Broom growing on a dune on Vancouver Island

Parks Canada needs to control IAS before the ecological integrity of native ecosystems is lost...

Saving wildlife

Parks Canada has been protecting native wildlife from IAS for a long time. Yet the number, diversity, and impacts of IAS is increasing. Climate change is making the issue more complex.

Global efforts are underway to reduce the rate of introduction and establishment of IAS by 50% by 2030. We protect ecosystems from IAS by collaborating with many groups, including:

  • Indigenous nations and communities
  • municipal, provincial, and territorial governments
  • universities and colleges
  • non-governmental organizations
  • business sector

Together, we use a range of approaches to track, prevent, and control IAS in protected areas administered by Parks Canada. We do this to protect the native species, biodiversity, and ecosystems that are special to national parks.

A grey and white bird is perched on the branch of an evergreen tree.
Clark’s Nutcracker in the Canadian Rockies

Read on for 3 short stories about this work

    Kejimkujik National Park and National Historic Site

  • Old growth forests and invasive insects

    Nova Scotia

    Aerial view of dense green forests around a blue lake with lush islands.
    Kejimkujik National Park and National Historic Site

    Kejimkujik National Park and National Historic Site is a protected area in the center of the broader Mi’kmaq cultural landscape of Kespukwitk, one of the seven traditional districts of the Mi’kmaq. It is a unique experience to walk among the Hemlock forests at Kejimkujik.

    Visitors are often filled with awe by the "cathedral" of old-growth trees. Their dense, feathery canopies give rise to a cool, mossy forest.

    Looking up at the dense canopy of a Hemlock forest.
    Old growth Hemlock forest in Kejimkujik
    A dense layer of moss covers the forest floor.
    The thick roots of a large tree have grown overtop of a large moss-covered boulder in the forest.

    Eastern Hemlocks can live to be over 400 years old and form among the last old-growth forests in Nova Scotia. These ancient trees play a vital role in the forest ecosystem at Kejimkujik by:

    • helping to mitigate the impacts of climate change by cooling streams
    • providing habitat for rare lichens, birds, and other species that rely on old growth forests
    • serving as a beloved and familiar sight for generations of campers and visitors

    Watch this video to learn more about the Eastern Hemlock and its importance to Kejimkujik:

    Text transcript Hemlock has always been a tree that's been a favorite for me because it just speaks of this steady, reliable presence in the Acadian forest.
    Right now in Nova Scotia, HWA started down in the Yarmouth area and trees down there are largely dead.
    We're a couple of years into infestation, but we have an option to do something right now.
    One has to have a healthy respect for this tiny, tiny creature in a very short time span, they can overwhelm a mighty hemlock tree. very little old growth left.
    Even in even in this park, we have only a few small stands of true old growth forest. So hopefully we can protect some of that.
    From Mi'kmaq First Peoples to current Keji park visitors. Eastern hemlock forests are our connection to the past, and they represent an ecological, cultural and historical legacy that we have to fight to protect.
    For more information on HWA and our efforts to protect Eastern hemlock:

    However, in 2018, the Hemlock Woolly Adelgid (HWA) was detected at Kejimkujik. This invasive alien insect damages and kills Eastern Hemlock trees. Scientists predict that up to 80% of all Hemlock trees in southwestern Nova Scotia will die by 2030 as a result of HWA.

    A close up of the branches of an evergreen tree with clusters of white dots covering the branches.
    Hemlock Woolly Adelgid has infested this Eastern Hemlock tree

    Parks Canada is working to save the forest ecosystem at Kejimkujik with many groups, like:

    • Mi’kmaq organizations, communities, and Nuji kelo'toqatijik (Earth Keepers)
    • provincial governments
    • the Mersey Tobeatic Research Institute
    • academic institutions
    • Friends of Keji and volunteers

    Parks Canada adopted an active management approach to respond to this new threat. To date, conservation actions have included:

    • restorative silviculture to cut weak and damaged Hemlock trees and to allow more light to reach the forest floor
    • growing the “forest of the future” with volunteers by planting diverse species for a more resilient Acadian forest
    • leaving some of the felled trees to help soil health and the newly planted seedlings
    • piloting the use of chemical insecticide by directly injecting priority trees in old-growth stands and important visitor areas
    • implementing a ban on outside firewood to prevent the spread of HWA and other invasive insects
    Protecting Kejimkujik's Hemlock legacy

    Select image to enlarge

    Parks Canada and partners are working to restore the ecological integrity of Kejimkujik and leave a legacy for future generations.

  • Waterton Lakes National Park

    Endangered butterflies and invasive plants


    A closeup of a brown butterfly on a yellow flower.
    Half-moon Hairstreak Butterfly

    The grasslands at Waterton Lakes National Park are the only critical habitat of the Half-moon Hairstreak Butterfly in Alberta. The presence of the Half-moon Hairstreak indicates a healthy ecosystem, along with many other butterfly species in Waterton Lakes. Butterflies are key pollinators and prey insects. They help pollinate the famous wildflowers that captivate the hearts of many visitors each year.

    Yet the invasive Spotted Knapweed is outcompeting native wildflowers, like the Silky and Silvery Lupine. The Half-moon Hairstreak Butterfly relies on these flowers for breeding.

     A field of purple, white, and yellow wildflowers surrounded by mountains.
    Silky Lupine flower in Waterton Lakes National Park
    A closeup of a brown butterfly resting on the leaf of a plant.
    The endangered Half-moon Hairstreak Butterfly in Waterton Lakes

    Watch how Parks Canada and the Calgary Zoo are helping the Half-moon Hairstreak Butterfly at Waterton Lakes National Park:

    Text transcript SOS! Half-moon hairstreak butterfly in distress!
    The half-moon hairstreak and its habitat are protected under the Species at Risk Act.
    In Alberta, Waterton Lakes National Park is the only place where the half-moon hairstreak butterfly exists.
    It lives on a floodplain known as the Blakiston Fan.
    The area is threatened by natural disturbances and invasive plants.
    Parks Canada and the Calgary Zoo are working together.
    To protect and restore the half-moon hairstreak population, teams use monitoring, habitat restoration and research to understand the butterfly’s life cycle.
    These research methods play a crucial role in the butterfly’s survival.
    The half-moon hairstreak depends on some of the most beautiful wildflowers in the park.
    It relies on native plants like lupines for food and a safe place to reproduce.
    Half-moon hairstreaks are important to the ecosystem. Both as a prey species and as a pollinator.
    Butterflies are important indicators of a healthy habitat. They are beautiful and fascinating insects to observe.
    Each summer, Parks Canada shares the story of the half-moon hairstreak with visitors.
    By staying on paths and not trampling on plants.
    And by cleaning equipment such as boots and bikes to prevent the spread of invasive plants.
    You help protect the half-moon hairstreak butterfly!
    A special thank you to the Calgary Zoo for collaborating on this project and providing footage.

    Parks Canada removes invasive grasses at Waterton Lakes to help prevent their spread. Conservation staff also restore threatened prairie grasslands to help native grass species recover. This work includes treating patches of invasive grass using herbicide and prescribed fire, and transplanting native prairie grasses.

  • Mountain national parks

    Endangered trees and invasive fungi

    Alberta and British Columbia

    The top of an evergreen tree with a snow-capped mountain in the background.
    Endangered Whitebark Pine in Jasper National Park
    Orange coloured sores ooze out of the trunk of a tree, breaking off the bark.
    White Pine Blister Rust, an invasive fungi

    The endangered Whitebark Pine and the Clark’s Nutcracker share a mutual friendship. The two species have evolved very closely together and rely on one other for survival.

    Watch this video to learn about their unique connection:

    Text transcript The Whitebark Pine and Clark’s Nutcracker are closely linked.
    Whitebark pine cones cannot open on their own.
    Instead, Clark’s Nutcrackers use their beaks to break open the cone for seeds.
    The seeds are large (about the size of a pea) and high in protein.
    Nutcrackers collect seeds in their sublingual pouch until it is full.
    The birds then bury the seeds to store food for the winter.
    Roughly half the seeds are forgotten and may grow into Whitebark pine seedlings.
    It can take between 80-100 years for a sapling to mature and produce seeds.
    Like. Comment. Share.

    The Nutcracker’s beak is specially designed to open the cones of Whitebark Pine and remove its nutritious seeds. The Nutcracker in turn helps Whitebark Pine spread and grow new seedlings.

    A bird rests at the top of an evergreen tree with a round seed held in its beak.
    Clark’s Nutcracker helps the endangered Whitebark Pine spread its seeds and grow new seedlings
    A close up of a pine cone.
    The pine cone of the Whitebark Pine tree

    Whitebark Pine is a long-living keystone tree species in mountain national parks. It is a pioneering species that helps other plant, animal, and soil communities flourish. Yet this tree is at risk of extinction due to an invasive fungus, White Pine Blister Rust. This fungus can kill large numbers of trees.

    To save Whitebark Pine and restore this important ecosystem, Parks Canada:

    • carefully monitors the invasion of White Pine Blister Rust
    • uses seed science, and seed collection through a technique called “caging”
    • partners with nurseries to grow a new generation of blister rust-resistant trees
    • restores Whitebark Pine to become a self-sustaining forest once again
    • applies conservation practices at the landscape level through prescribed fire
    • delivers visitor education
    A Parks Canada staff person is harnessed mid way up a tall evergreen tree.
    Conservation staff at Waterton Lakes National Park scaling a Whitebark Pine tree to monitor for White Pine Blister Rust.
     Two Parks Canada staff at the top of a mountain kneel near an evergreen tree that has mesh cages covering some branches.
    Cages are applied around cones to save them from being eaten. Cones are transferred to a nursery to grow.

    Conservation staff and volunteers have planted thousands of Whitebark Pine and Limber Pine seedlings in Waterton Lakes National Park.

    There’s a lot of hope involved in keeping a really positive attitude about what we’re doing.

    Brenda Shepard
    Ecologist, Jasper National Park

    Watch how this work unfolds across the mountain national parks:

    Text transcript [Brenda] There have been a couple of whitebark pine in the Canadian Rockies that have been aged around 1000 years old.
    I mean these trees have seen such incredible change in the world since they were seedlings like the ones we’re planting.
    All of the Mountain Parks, so that’s Waterton, Revelstoke-Glacier, Kootenay, Yoho, Banff and Jasper.
    We all work together, we’re relying on each other trying to recover Whitebark Pine and limber pine together.
    Whitebark Pine is a pioneering species and so it moves in and it creates, often, these little tree islands and other species are able to move in after it.
    [Allison] My favourite thing about Whitebark Pine, the fact that nutcrackers are almost exclusively responsible for allowing them to regenerate.
    [Hilary] I love that they just grow in these really rough exposed areas and that they are so resilient and they just live for hundreds of years.
    [Genoa] Once we found a limber pine that was just growing straight into a cliff, like it’s surviving and thriving.
    [Rebecca] These trees have an absolutely crucial role in both the plant communities and the animal communities, the soil communities, probably more communities than we understand right now. [Laugh]
    [Brenda] The Clark’s Nutcracker and the Whitebark Pine have a really important relationship.
    It’s called a mutualism, really rare in nature, where both species depend on each other for their survival.
    The cones will not open on their own.
    The nutcracker has a specialized beak to be able to open the cones and then it will fly off to different parts of the forest where it will deposit seeds and then months later they will fly back, find that exact spot and dig out the seeds and eat them.
    And it’s only seeds that they don’t eat that become Whitebark Pine seedlings.
    They evolved together, these two species, over tens of thousands of years.
    [Allison] So you can see that kind of spindle shape, there’s a lot of swelling, coarse bark, and you can see some of the inactive rust oozing out, and then this section of the branch is all dead.
    [Brenda] These trees did not evolve with white pine blister rust and that’s what’s really important about why this causes the tree to become endangered.
    This disease came in in the early 1900’s and the tree just doesn’t have the traits to be able to fight it off.
    So we worry about these big ghost forests.
    If there are ghost forests, will there not be enough Whitebark Pine to attract nutcrackers and if there are no nutcrackers, there’s no future.
    We climb the tree in the early summer.
    We put cages on the cones, the cones mature, but they don’t get eaten by birds or squirrels.
    We climb back up late September, pick the cones and then the cones dry and then we extract the seeds from the cones.
    We send those seeds to a nursery and then the nursery spends two years growing these guys.
    We want to plant enough trees at a high enough density that in eighty years we will have a forest of cone producing trees that will attract Clark’s Nutcrackers back and these birds will continue to allow these stands to persist and so that’s how we will create these self-sustaining recovered Whitebark Pine stands.
    So there’s a lot of hope involved in keeping a really positive attitude about what we’re doing, the fact that none of us here will be alive to know whether this was successful.

Strange encounters

Staff have identified IAS in most national parks. There are many ways that IAS can enter a protected area, some more obvious than others. Common vectors can be:

  • people, including on their shoes, clothing, pets, cars, ATVs, boats, as well as travel along roads and trails
  • once introduced to an area, IAS can be carried by wildlife, or by wind and water
A close up of a pair of boots covered in mud and plant debris.
Clean muddy boots and other gear to remove soil and plant debris that can spread invasive species
A close up of a species of wheat grass.
Invasive Crested Wheatgrass can be carried by wind or on shoes

Less obvious vectors include imported earth materials, seed mixes, livestock and feed. All these possible entries into protected areas make it difficult and costly to prevent and control IAS.

On the bright side—knowing how IAS can enter a protected area helps you protect native wildlife and ecosystems.

Setting priorities and taking action

Sometimes it is not feasible to control all of the IAS in a protected area. Often staff need to determine which populations of IAS pose the greatest threat. Parks Canada scientists use the best available research and information to prioritize conservation actions based on the:

  • population size of IAS
  • impacts to native species and ecosystems
  • vulnerability of the area at risk
  • scope of spread across site
  • source and likelihood of spread
A dense patch of greenery crowds the water’s edge.
Invasive Garlic Mustard and invasive Purple Loosestrife
A dense growth of purple flowers crowds out the open water habitat of a pond.
Conservation staff at Prince Edward Island National Park are managing the removal of both of these invasive alien plants

Detecting IAS and preventing spread

Early detection of IAS can be tough. Conservation scientists, along with partners, strategically monitor new and existing IAS in protected areas using:

  • ground surveys
  • wildlife cameras
  • aerial imagery, fly-overs, and drone flights
  • formulas for calculating relative threat
  • visitor observations
One Parks Canada staff uses a quadrat to count vegetation in a small area while another staff member records the data on a clipboard.
Parks Canada conservation staff monitor vegetation
A wildlife camera photo taken at night of a group of wild pigs.
A wildlife camera captures a sounder (group) of invasive wild pigs
A small vegetated island spits out of a larger vegetated island.
Sidney Island is home to the Garry Oak ecosystem and now several invasive species

Parks Canada works to contain a population or source of IAS once it is identified as a threat. To prevent the spread of IAS, staff scientists target the source of the spread and protect areas where IAS could disperse. Parks Canada also engages visitors with actions they can take to help slow the spread of IAS.

Controlling IAS

Once an IAS has become established, it can be very difficult to remove. Parks Canada carefully prioritizes actions that target IAS. Conservation actions should minimize further impact to biodiversity and ecosystems. This requires a long-term, on-going commitment.

Parks Canada draws on science and Indigenous knowledge to determine the safest and most effective methods to control IAS in areas disturbed by introductions of IAS. Parks Canada develops Integrated Pest Management plans that can include a mix of:

  • mechanical controls, like mowing, pulling, trapping
  • chemical controls, like herbicides, pesticides
  • prescribed fires
  • introduced biological controls
  • restoration activities, like planting or re-introductions of native species, to restore balance to ecosystems

Conservation staff at Fundy National Park help prevent the regrowth of invasive Japanese Knotweed in several ways. This includes covering it from sunlight and pulling the plant where covering is not possible. Doing so depletes the plants’ energy over time while avoiding the use of herbicides. Conservation staff at Elk Island National Park are working with the province of Alberta to trap invasive wild pigs that are causing widespread damage.

A dense cluster of broad leafy foliage with small white flowers.
Japanese Knotweed is an invasive alien plant found growingly across in Eastern Canada
A group of wild pigs scattered across an area without grass in a forest.
Invasive wild pigs can damage vegetation and ecosystems as they wallow across the Canadian Prairies

Restoring ecosystems after an invasion

Parks Canada scientists restore ecosystems and species that have been affected by introductions of IAS. Conservation staff at Grasslands National Park are restoring the critical native habitat of Greater Sage-Grouse from Crested Wheatgrass and Smooth Broome, two invasive grasses. Before seeding six different native grass species, staff remove the Crested Wheatgrass from the field and any seeds that may be left in the soil.

Staff scientists at Gulf Islands National Park Reserve are collaborating with the Coast Salish First Nations to restore the Garry Oak ecosystem from invasive plants, like Scotch Broom. Efforts are also underway with First Nations and partners to restore the Douglas-fir ecosystem from invasive deer and plants, including Scotch Broom.

A close up of a green meadow filled with uniquely shaped purple and white flowers.
Wildflowers in the Garry Oak Meadow ecosystem

Show love for native biodiversity—ways you can help

Invasive alien species can feel like a daunting issue to prevent and control. Yet there are ways to do your part to slow and prevent the spread of IAS!

  • Do not move outside firewood into national parks to prevent the spread of IAS, like the Emerald Ash Borer and Hemlock Woolly Adelgid
  • Stop invasive species in your tracks! Play. Clean. Go!
    • Remove plant parts and mud from boots, clothing, and pets
    • Clean your gear before entering or leaving the national park
    • Report non-native plants using the iNaturalist app
  • Be a responsible gardener. Learn which plant species are invasive in your region and find alternatives. Search your local Invasive Species Council for more ways to help, like these "Grow me Instead" guides for British Columbia and Alberta
  • Volunteer to help control invasive species. Learn about, and fall in love with, your local native biodiversity!
  • Talk with your friends and family about IAS and how they can help
    A close up of a person holding seeds and planting them into the soil.
    Be a responsible gardener! Understand the species of plant you grow in your garden to avoid introducing invasive alien species into your area

Date modified :