2. What is an invasive species?
What makes them invasive?
Why do we care?
What is the government doing?
Invasives in Texas
Invasives in the U.S.
Invasives in other parts of the world
3. An "invasive species" is defined as a species that is
non-native (or alien) to the ecosystem under
consideration and whose introduction causes or is
likely to cause economic or environmental harm or
harm to human health. (Executive Order 13112).
Most commonly associated with harm to ecosystem
and/or native species
Non-native vs. Invasive
4. Some intentionally introduced
European Starling introduced as part of a plan to have
all the species in the works of Shakespeare in the U.S.
Accidental introduction
Fire ants on a ship from South America
Bred/introduced with good intentions
Africanized “killer” bees were meant to produce more
honey
5. Common Traits of Invasive Species
Able to reproduce quickly
Fast maturation rate
Able to disperse quickly
Tolerant to wide range on environments
Tend to be generalists
Able to tolerate some human interaction
These traits allow invasive species to outcompete
native wildlife
6. One species can have a major impact on an ecosystem
Niches that are already occupied
Preserving native wildlife
7. National Invasive Species Council (NISC) was
established by Executive Order 13112
February 8th, 1999
Manages invasive species at a national, state, and even
ecosystem level
Composed of members 13 federal departments and
agencies
Includes the EPA, USDA, USFWS, etc.
Drafts the budget for invasive species
Provide advice for other nations
8. Many different methods employed
Some invasive species are only “controlled” while the
government attempts to eliminate others
Plants
Herbacides
Manual removal
Animals
Trapping
Birth control
Poisoning
Shooting
9. Nutria
Semi-aquatic rodent
Sexually mature at 4 months
Breed year round
Introduction
Introduced for the fur trade (CA, WA, OH, MI, OR, LA,
NM)
Spread to other states to control undesirable vegetation
Threat
Destroys millions of dollars of crops each year
Destroys native aquatic vegetation
10. Hydrilla
Aquatic Plant
Very hardy
Can grow 1 inch a day
Introduction
Introduced for aquarium trade
Reproduces from stem fragments dispersed by waterfowl
Threat
Raises water pH and temperature
Limits number of large fish
11. Fire Ants (Red imported fire ant)
Live in large colonies
Able to tolerate wide range on environments
Reproduce very quickly
Introduction
On a cargo ship from South America that docked in Alabama
Threat
1.2 billion dollars in Texas annually
Damage native plants and animals
Negatively impact
red ants/Texas Horned Lizard
12. Silver Carp
Asian carp species
Weigh up to 100 lbs.
Move up river 50 miles per year
Reproduce extremely rapidly
Introduction
Introduced to Illinois and Mississippi Rivers to help control
algae and as a food source
Threat
Damage to boats
Outcompete other native species of filter feeders (other carp
and mussels)
Feared to eventually become the dominant species in the
Great Lakes
13. Zebra Mussel
Small mussel at about 3.5-4 cm
High Rate of filtration
Able to tolerate wide range of temperatures
Introduction
Thought to have spread from Eurasia to United States by
ballast water released from sea-going ships
Threat
High rate of filtration lowers amount of green algae
Feed on zooplankton
Increase depth of light penetration
14. Ring-necked Pheasant
Well-known game bird in America
Able to tolerate fragmented habitat
Thrives near humans
Introduction
Introduced from Georgia to Oregon as a game bird in
1881
Threat
Threat to the Lesser Prairie Chicken
Lekking
Competition for Resources and Habitat
15. Brown Tree Snake
Native to Australia, Indonesia, and Papua New Guinea
3 – 6 feet in length
Reproduce year round
Introduction
Accidentally introduced in Guam from a cargo ship from
the South Pacific
Threat
No natural predators on the island
Lead to extinction of the majority of vertebrate species
on the island, especially birds
Causes power outages
16. Red Fox
5 – 31 lbs
Will consume a wide variety of prey
Listed as one of worlds 100 worst
invasive species
Native to Europe, Asia,
and North America
Introduction
Intentionally introduced to Australia between 1855 and 1871 to
control European rabbits
Threat
Threat to biodiversity
Major predator of various species of Wallabies, as well as
other fauna
17. Giant Hogweed
Native to Asia
Can grow to over 18 feet tall
Spreads very quickly
Introduction
Brought to Ireland as an ornamental plant for gardens and
parks
Threat
Health hazard
Able to outcompete native plants by growing rapidly and
blocking sunlight
Decreases invertebrate biodiversity by limiting plants that
serve as food sources
18. Do you think the Government should control invasive
species?
Do you think humans should be considered an
invasive species?
Have you ever directly seen the impact of an invasive
species?
