Lecture 11- Invasive species Flashcards
Definition of introduced/non-native/exotic/alien/non-indigenous species:
A species living outside its natural geographic range as a consequence of human activity
Definition of invasive species:
A non-indigenous plant or animal that adversely affects its habitat ecologically or economically
Definition of naturalized species
An introduced or invasive species that has been present for such a period of time as to become viewed as part of the natural ecosystem
Examples of deliberate invasive species arrival?
Livestock/food e.g. European rabbit Biocontrol agents e.g. Indian mongoose Companion animals e.g. cat Hunting quarry e.g. red fox Aesthetic reasons e.g. grey squirrel
Examples of accidental invasive species arrival?
Commensal rodents e.g. musk shrew Shipwrecks Escapes from - Agriculture: goats, sheep, pigs Companion: cat, exotic pets Fur farms: mink, coypu Zoos: reeves muntjac Research labs: primates
Impact of invasive species on other species can occur at 5 different levels which are?
1) Individual
2) Genetic
3) Population
4) Community
5) Ecosystem
Examples of genetic impacts?
Scottish wildcat & feral cat
Red deer & sika
Polecat & ferret
Examples of population impacts
Predation - red fox, domestic cat–brown rat, house mouse
Competition - European rabbit in australia
Disease/parasites
Example of community impacts
Rabbit and red fox combined
Example of ecosystem impacts
Disruption of fire regimes, flooding, soil erosion
Examples of hyperpredation?
Substantial interaction between rabbits and foxes that has exacerbated the impact of foxes
California channel islands - Feral pig-Golden Eagle-fox
What is meso-predator release?
Where one predator suppresses abundance of a lower predator, such that absence of top predator leads to increased abundance of lower predator
How to manage invasive species?
Prevent introduction Reduce to acceptable level Eradication e.g. rats and mice - poisoning rabbits, goats, pigs - shooting cats - trapping, shooting musk shrew - trapping
4 management issues:
1) most expense incurred in getting rid of last few individuals
2) must be limited option for recolonization
3a) hyper predation, must control: predator and prey simultaneously
3b) meso-predation release - control of one predator can lead to increase predation by a second predator
4) wildlife management is a political problem
