Invasive Species. Also the topic of our new course. An exciting topic which may be the most important conservation issue today. So, what is an invasive species?. Monk Parakeet colony near Chicago, Illinois. Can you find Guam and New Guinea on a map of the world? .
Also the topic of our new course
An exciting topic which may be the most important conservation issue today
Monk Parakeet colony nearChicago, Illinois
Brown Tree Snake introduced to Guam, but they are native to New Guinea
"Exotic," "alien," "introduced," non-indigenous," and "non-native" are all synonyms for plant or animal species that are intentionally or unintentionally introduced into an area outside of their natural range.
1. Suitability of Habitat and Ecological Niche
b. Behavior- including social aspects
c. Simple numbers
3. Degree of escape from diseases, parasites and predators
4. Degree of escape from competitors
European Rabbits in Australia
1. Direct competition for food
2. Selective grazing changes ecosystem composition
3. Evicted various species from their burrows- e.g. bilby, hare-wallaby
4. A colony of rabbits will support a high number of predators (e.g. feral cats and introduced foxes) which will shift to other, more easily obtained, native prey
5. Native wildlife killed by poisons and traps set for rabbits
6. Shooters, culling rabbits, also culled native species for the pelt trade.
7. Bounties paid for wombats, why?
8. Harm to vegetation during drought- digging of roots and ringing
Red Fox introduced to control rabbits, but decimated native fauna, also …..
Present distribution of Rusty Crayfishrange intentionally expanded by anglers
Rusty crayfish (Orconectes rusticus) are native to streams in the Ohio, Kentucky and Tennessee region. Spread by anglers who use them as bait, rusty crayfish are prolific and can severely reduce lake and stream vegetation, depriving native fish and their prey of cover and food. They also reduce native crayfish populations
Cattle Egret- native to Africa, first crossed to South America then into the United States in the 1940’s
1. Ecological distinctiveness- highly successful invaders are usually different in structure, physiology or behavior from native forms
Kudzu, a keystone exotic species infestation in Georgia. Keystone species are those, that if lost, would precipitate an extinction cascade or vortex
Zebra Mussel- introduced into the Great Lakes in the ballast of oceanic ships
Determinants for Impact
2. Potential for competitive exclusion
Zebra Musses attached to the shell of a native mussel in the Ohio River
One of the more drastic impacts of zebra mussels are their influence in causing the near extinction of native American unionid clams in Lake St. Clair
Zebra mussels attached to a native clam found within the Great Lakes region
Terrible waste of a good beer can
Zebra mussels attached to a crayfish (top) and a snapping turtle (bottom)
Zebra mussels encrusted inside water pipes
3. Potential for disease transmission
Fungi accidently introduced on Chinese Chestnut trees imported to the United States, the map documents the timing of the spread
4. Potential for genetic swamping
Rainbow trout introduced for anglers, readily hybridizes with native species such as cutthroat trout.
1. Prevention of entry
2. Control of spread
3. Creation of pristine areas
4. Local eradication
5. Protection of individuals
6. General population reduction