Habitat loss and fragmentation, Habitat loss from tropical rainforest/The Amazon rain forest is being cut and cleared/for raising cattle/for conversion to grass lands/for cultivating soyabeans/large habitats are broken up into small fragments due to human activities/mammals and birds requiring large territories are badly affected leading to decline in population.
Over exploitation, when 'need' turns 'greed' lead to over exploitation of natural resources/steller’s sea cow/passenger pigeon were over exploited/marine fish populations around the world are over exploited/endangering existance of commercially important species.
Alien species invasions, when introduced unintentionally or deliberately for any purpose some of them turn invasive and decline indigenous species/carrot grass/parthenium/African cat fish/Clarias gariepinus poses threat to indigenous cat fishes of our river.
Co-extinctions, when a species becomes extinct the plant or animal species associated with it (an obligate way) become extinct/when a host species becomes extinct (its unique assemblage of) parasites meets the same fate/extinction of any member in plant pollinator mutualism leads to extinction of other.