Major causes of biodiversity loss

Reasons for biodiversity losses are multifaceted and factors may interact synergistically
Causes of population decline:
Habitat alteration
Invasive species
Pollution
Overharvesting
Climate change

Habitat alteration
The greatest cause of biodiversity loss
Farming simplifies communities
Grazing modifies the grassland structure and species composition
Clearing forests removes resources organisms need
Hydroelectric dams turn rivers into reservoirs upstream
Urbanization and suburban sprawl reduce natural communities
A few species (i.e., pigeons, rats) benefit from changing habitats