Field Guide to Invasive Species

Atlantic salmon (Salmo salar):

• Description: The adult averages 3 to 10 kg in weight and 90 cm in length; is blue-black with bright silver flanks, whitish anal fin, and relatively distinct lateral line.
• Native Range: Atlantic coast of North America.
• Invasive Range: Pacific Coast of Canada.
• Invasion Pathway: Escape from aquaculture operations and hatcheries.
• Ecological Impacts: Hybridizes with, and genetically contaminates, Pacific salmon populations; competes aggressively for food and habitat.

Brown spruce longhorn beetle (Tetropium fuscum):

• Description: This brown and black flying insect reaches about 2.5 cm long; has two long, reddish antennae and two or three faint stripes down length of dorsal wing cover.
• Native range: Europe
• Invasive Range: One known site in Halifax, N.S.
• Invasion Pathway: Arrived in wood-based packing materials from overseas.
• Ecological Impacts: Burrows under bark of native red and white spruce trees to lay eggs; most infested trees are killed.

Bull­frog (Rana catesbeiana):

• Description: This large amphibian can grow up to 20 cm long, not including the hind legs; adult varies from bright to brownish green; has strong, muscular hind legs, fully webbed back feet, and a prominent tympanum (round eardrum) behind each eye.
• Native Range: Eastern North America, from southern Ont. To Fla.
• Invasive Range: Southern Vancouver Island and southwestern B.C.
• Invasion Pathway: Introduced into B.C. for frog-leg farming and ornamental ponds.
• Ecological Impacts: Competes for habitat with native species, including tailed frog, red-legged frog, and western toad.

Dead man's fingers (Codium fragile):

• Description: This marine alga, or seaweed, consists of multiple branches stemming from a single disc-like pad, or holdfast; branches are pale to dark green, cylindrical, and covered with numerous long hairs.
• Native Range: Coastal waters of Japan
• Invasive Range: Shallow coastal waters of Atlantic Canada, especially N.S.
• Invasion Pathway: Attaches to hard surfaces; likely introduced to North America on hulls of transoceanic ships and shells of imported shellfish; spreads rapidly in warm, shallow coastal waters.
• Ecological Impacts: Competes for space with native kelp; kills oysters and clams by attaching to their shells; can harm other marine life by damaging habitat.

Domestic cat (Felis catus):

• Description: Typically 3 to 5 kg in weight, 35 cm tall, and about 75 cm long, including tail. Colouration varies, but feral cats revert to wild-type tabby markings within a few generations.
• Native Range: Originally from Africa and Asia
• Invasive Range: Worldwide
• Invasion Pathway: Feral population is maintained through accidental and intentional release of companion animals; free-ranging house cats contribute to ecological impacts as well.
• Ecological Impacts: Preys on large numbers of small birds and mammals.

European Starling (Sturnus vulgaris):

• Description: Both the male and female of this medium-sized songbird are glossy black with iridescent green and purple on the head, back, and breast; male has bright yellow beak in springtime; otherwise, beak and legs are dull yellow to grey.
• Native Range: Europe and Asia
• Invasive Range: Throughout Canada and the U.S.
• Invasion Pathway: Introduced in New York City through release of 100 birds by group dedicated to bringing to North America all birds mentioned in Shakespeare’s works.
• Ecological Impacts: Competes for space with, and often preys upon eggs and nestlings of, native birds; often usurps nesting cavities of woodpeckers, bluebirds, swallows, and other birds.

Flowering rush (Butomus umbellatus):

• Description: An aquatic plant with tall, narrow, upright leaves and long shoots ending in clusters of about 30 flowers; each flower has three pink sepals, three pink petals, and bright orange pollen on nine stamens.
• Native Range: Europe and Asia
• Invasive Range: B.C., Alta., Man., southwestern and eastern Ont., Que., N.S.
• Invasion Pathway: Escaped into the wild from ornamental ponds; is spread further by boats and diving equipment.
• Ecological Impacts: Habitat destruction and displacement of native plants.

Green crab (Carcinas maenas):

• Description: A small marine crab, measuring up to 6.5 cm across the carapace (upper shell); adults are dark grey-green; juveniles can be mottled green or orange; hind legs are slightly flattened with sharp tips
• Native Range: European North Atlantic and Baltic Sea
• Invasive Range: East and west North American coasts, including B.C., N.B., N.S., P.E.I.
• Invasion Pathway: Accidentally imported to North America in shipments of live bait and lobster; has since spread rapidly.
• Ecological Impacts: Preys extensively on native mollusks, causing population declines and harming shellfish industry.

Knapweed (Centaurea maculosa, Centaurea diffusa):

• Description : These members of the aster family range from 20 to 100 cm high with numerous spreading branches; round, hairy flowers bloom from July to September; spotted knapweed exhibits black-tipped flower heads and shiny, round glands on surface of leaves that give spotted appearance; diffuse knapweed displays white or pinkish flowers with short rigid spines on flower heads.
• Native Range: Europe and Asia
• Invasive Range: Throughout Canada except N.B., N.S., and P.E.I.
• Invasion Pathway: Probably accidentally imported with alfalfa and hayseed.
• Ecological Impacts: Forms dense stands that crowd out native flora in grasslands and forests.

Leafy spurge (Euphorbia esula):

• Description: A perennial grassland plant, from 60 to 75 cm high; erect, many-branched stem contains white, milky sap; flowers are small, yellow, and arranged in groups of three; leaves are small and lance-shaped, with frosted appearance and wavy margins.
• Native Range: Europe and Asia
• Invasive Range: Southern B.C., Alta., Sask., Man., Ont., Que., N.S., P.E.I.
• Invasion Pathway: Introduced in ballast water dumped by merchant ships and as a contaminant in imported seed stock; continues to spread through seed dispersal aided by birds.
• Ecological Impacts: Grows rapidly and is toxic to wildlife; crowds out native grasses and reduces quality of forage sites and grazing pastures.

Northern Snakehead (Channa argus):

• Description: This torpedo-shaped freshwater fish with a snakelike head weighs an average of about 9 kg and reaches up to 1 m long; juvenile has reddish brown back with prominent stripes but fades with age to dark greenish, purplish or brownish back with lighter silver underside; can travel across land on extended fins and survive out of water for several days.
• Native Range: China
• Invasive Range: Cal., Fla., Md., Mass; likely to spread to Ont.
• Invasion Pathway: Probably dumping from aquariums and escapes from small fish farms serving restaurant industry.
• Ecological Impacts: A voracious predator that can spread between freshwater lakes and ponds, the snakehead reproduces rapidly and can cause drastic declines in amphibian, insect, and fish populations.

Purple loosestrife (Lythrum salicaria):

• Description: This perennial plant can grow up to 2 m high and is covered in short hairs; has stout stems with opposing or whorled, lance-shaped leaves ranging from 3 to 10 cm long; displays many spikes of densely clustered rose to reddish purple flowers in mid-summer.
• Native range: Europe and Asia
• Invasive Range: Across southern Canada
• Invasion Pathway: Spread to the wild from ornamental gardens.
• Ecological Impacts: Spreads quickly and competes aggressively with native flora, often completely taking over habitat.

Red-Eared Slider (Trachemys scripta):

• Description: A medium-sized turtle characterized by a dark olive to black carapace (upper shell) covered with bright yellow stripes and bars; head colouration is similar except for a bright red or orange streak behind each eye.
• Native Range: Southeastern U.S
• Invasive Range: B.C., southern Ont., particularly around Great Lakes
• Invasion Pathway: Most frequently introduced into wild through escape and intentional release from pet trade.
• Ecological Impacts: Competes with native pond turtles for food and basking sites.

Scotch Broom (Cytisus scoparius):

• Description: This perennial shrub is a member of the bean family; grows best in dry, cultivated regions, stands 1 to 3 m tall and is profusely branched; displays solitary and paired bright yellow flowers and leaflets arranged in groups of three.
• Native Range: Central and southern Europe
• Invasive Range: B.C., N.S., P.E.I.
• Invasion Pathway: Originally cultivated as an ornamental plant; has since spread into the wild.
• Ecological Impacts: Invades cultivated fields, open areas, sandy roadsides, and old riverbeds; competes aggressively for moisture and damages agricultural fields.

Spiny water flea (Bythotrephes cederstroemi):

• Description: This predatory crustacean is an intruder among the zooplankton of the Great Lakes; adult ranges from 1 to 1.5 cm long, more than half of which constitutes long, barbed tail; body is covered in spines and multi-coloured, with red dorsal stripe down part of tail.
• Native Range: Caspian Sea and central Asia
• Invasive Range: Great Lakes
• Invasion Pathway: Reached Canada via ballast water release; spreads through bait bucket dumping.
• Ecological Impacts: Competes with native predatory zooplankton (including Daphnia and Leptodora); disrupts food chain as it cannot be eaten by smaller fish, such as juvenile yellow perch.

Zebra mussel (Dreissena polymorpha):

• Description: The adult of this small bivalve mollusc measures only 1 to 2 cm across; has D-shaped, darkly striped shell, for which it is named; tends to live in large clusters rather than individually.
• Native Range: Black and Caspian Seas
• Invasive Range: Great Lakes and surrounding water systems
• Invasion Pathway: Larvae are accidentally transported in ballast water; adults attach to boats, diving equipment, and other hard surfaces.
• Ecological Impacts: Competes aggressively with native molluscs; forms dense colonies that cover hard surfaces, including shells of other molluscs (causing death) and many human-made structures; has contributed to reduction of phytoplankton and displacement of Diporeia hoyi, a native burrowing crustacean.