WHAT ARE THE STEPS TOWARD EXTINCTION?

Almost everyone knows about the American alligator. But did you know we also have an American crocodile? The species is native to coastal areas of peninsular Florida. Its full geographic range includes Central America, northern South America and many Caribbean islands. The U.S. Fish and Wildlife Service placed these typically inoffensive creatures in the threatened category under the federal Endangered Species Act. This triggered protective measures that have led to a 10-fold increase in their numbers. Some wildlife biologists estimate population numbers were once as low as 200 in Florida.

The USFWS defines an endangered species as one “in danger of extinction.” A threatened species is one “likely to become an endangered species within the foreseeable future.” Extinction, and the paths leading to it, can be roughly divided into categories based on the underlying cause of a species’ demise and its present condition. Below is one such arrangement.

5. No human involvement. Dinosaurs and millions of other species can be placed in the category of prehuman extinction, the end-line of natural evolutionary processes, a condition no human can be blamed for.
6. Bygone ancestors. Human-caused extinctions (e.g., Passenger pigeons, Carolina parakeets and dodos) for which no one alive today can be held accountable.
7. Present-day culprits. Some species that existed in our lifetime are no longer present. Humans living today can be held responsible, some much more than others, for most modern extinctions. The causes include such obvious ones as direct killing, unregulated pollution and foremost— human destruction of natural habitats.
8. Commercial overkill. A commercially extinct species is no longer economically feasible to harvest, although the species may be present, even abundant, in some areas. Commercial extinction can be a precursor to eradication. Some experts consider the Atlantic codfish, once a New England staple, to be nearing commercial extinction.
9. Ecological extinction. A species is considered ecologically extinct when it has disappeared from its native habitat, though a few members may survive in captivity.

Unfortunately, commercial or ecological extinction is too often the point at which we begin to pay attention to the plight of a species—and that’s often too late. Once a species becomes ecologically extinct, keeping it extant (in existence) requires putting it on biological life support. The California condor was ecologically extinct until USFWS programs demonstrated that recovery was possible. This magnificent species persisted for a while on a human-designed welfare system, with the young raised in captivity. Some now live free, but their situation is still precarious—as anyone’s might be while clinging to a cliff in the Grand Canyon.

Commercial and ecological gray zones of impending extinction should attract our notice. Is the species declining in abundance or geographic distribution? Consider the spotted turtle. This little black turtle with bright yellow spots on its shell unquestionably has declined in numbers throughout its range. One of the prettiest turtles in North America, the spotted turtle may well be declared a modern-day extinction within the span of a couple of human generations. Two reasons are apparent.

First, spotted turtles are popular pets, and people who like pet turtles will pay a lot of money for them. Thus turtle collectors capture them in the wild, mostly illegally, for the pet trade. The other assault on spotted turtles comes from habitat destruction. Like so many other wildlife species, they depend on wetland habitats for their survival. The loss of small, marshy wetlands means a decrease in suitable wildlife habitat. The spotted turtle could be on a trajectory toward ecological extinction.

The American crocodile could again be flirting with extinction in Florida as a result of commercial development. Hundreds of other examples would serve as well. We should protect all wildlife now—before they become commercially or ecologically extinct. Let’s address how habitat loss and overharvesting affect their life cycles and ecology today, so we do not have to institute welfare and life-support systems tomorrow.

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