Introduced non-native species
Compete for resources is no known predator
Native species population goes down
Population size/density
Too many humans will crowd out wildlife environment cannot maintain ideal carrying capacity
Resource use/ habitat destruction
When a resource or habitat disappears species are now competing for limited resources. # down
Pesticide
Pollution/toxic can be passed up a food chain. (Biomagnification) # down at top of food chain
Pollution
May contaminate water source. Competition increases over limited source, #down