HOW DO HUMANS ACCELERATE SPECIES EXTINCTION?

Loss of Habitat Is the Single Greatest Threat to Species:

Remember HIPPCO shows the underlying and direct causes of the endangerment and extinction of wild species. Biodiversity researchers summarize the most important direct causes of extinction resulting from human activities using the acronym HIPPCO: Habitat destruction, degradation, and fragmentation; Invasive (nonnative) species; Population growth and increasing use of resources; Pollution; Climate change; and Overexploitation. According to biodiversity researchers, the greatest threat to wild species is habitat loss, degradation, and fragmentation. A stunning example of this is the loss of habitat for polar bears. Because the atmosphere above the Arctic has been getting warmer during the past several decades, the floating sea ice that is a vital part of the bears’ habitat is melting away beneath their feet, which is causing a decline in their numbers. Deforestation in tropical areas is the greatest eliminator of species, followed by the destruction and degradation of coral reefs and coastal wetlands, the plowing of grasslands, and the pollution of streams, lakes, and oceans. Island species—many of them found nowhere else on earth—are especially vulnerable to extinction when their habitats are destroyed, degraded, or fragmented and they have nowhere else to go. This is why the collection of islands that make up the U.S. state of Hawaii is America’s “extinction capital”—with 63% of its species at risk. Habitat fragmentation occurs when a large, intact area of habitat such as a forest or natural grassland is divided, typically by roads, logging operations, crop fields, and urban development, into smaller, isolated patches or “habitat islands” . This process can decrease tree cover in forests, and block animal migration routes. It can also divide populations of a species into smaller, increasingly isolated groups that are more vulnerable to predators, competitor species, disease, and catastrophic events such as storms and fires. In addition, habitat fragmentation creates barriers that limit the abilities of some species to disperse and colonize new areas, to locate adequate food supplies, and to find mates. Most national parks and other nature reserves are habitat islands, many of them surrounded by potentially damaging logging and mining operations, industrial activities, coal-burning power plants, and human settlements. Freshwater lakes are also habitat islands that are especially vulnerable to the introduction of nonnative species and pollution from human activities. Scientists use the theory of island biogeography (According to this widely accepted scientific theory, the number of different species (species richness) found on an island is determined by the interactions of two factors: the rate at which new species immigrate to the island and the rate at which species become locally extinct, or cease to exist, on the island) to help them understand the role of fragmentation in species extinction and to develop ways to help prevent such extinction.