The species that have decreased, however, outnumber the species that have increased. The reason, or reasons, analysts say, is HIPPO, an acronym for habitat destruction, invasive species, population, pollution and over harvesting.
Habitat destruction is plowing a grassland, converting it to crop land.
It’s draining a marsh. It’s cutting a forest or woodlot. It’s clearing the banks of a stream or river, straightening and dredging the channel.
Invasive species are both animal and plant. They’re starlings nesting in cavities and bird houses that might otherwise be used by bluebirds.
They’re ring-billed gulls nesting in such numbers that they crowd out common terns. They’re multiflora rose and reed canary grass, garlic mustard and purple loosestrife where native plants, plants more beneficial to birds once grew.
Pollution is carbon dioxide and other chemicals spewed into the air. It’s pesticides sprayed on forests and fields. It’s effluent poured into rivers and streams and the oceans. It’s runoff from animal feedlots. It’s acidic waste from mining. It’s herbicides on lawns, killing dandelions and other weeds and also insects and worms. It’s garbage in open dumps and litter strewn along roads and highways, hiking and biking trails.
Over harvesting is too much hunting. This was a serious problem. Hunting seasons, bag limits, closed seasons, restrictions on methods of hunting have largely controlled this problem now.
In my opinion there should be another letter in HIPPO, a third P. A “P” for people. We create the habitat destruction. Not all of it. Hurricanes and typhoons, tornadoes, floods, earthquakes and volcanic eruptions also cause habitat destruction. But people cause more.
We have introduced species into new areas, intentionally and inadvertently. We create the conditions that lead to over population. We cause the pollution. We are the harvesters.