Why protect habitat alone?

Reposted from the old TfK.

Pc312916-1-ViI suggested at the bottom of a longish post that the Endangered Species Act ought to be supplemented with an Endangered Ecosystem Act.

The reason begins with thinking like a mountain. If you’ve read the last post and my Thinking Like a Savannah and you haven’t read Aldo Leopold’s Sand County Almanac, or at least its essay ?Thinking Like a Mountain? just do it, and come right back.

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OK, so now you understand what ecologists have known for 50 years ? that the important thing in conservation is not the individual animal or even, perhaps, the individual species. Some species are more important than others to the system.

Ecologists can and do argue for decades about how to decide how to measure importance. Do you look at which species is connected to the most other species in the food web? At which species’ removal would have the greatest effect on that food web? At which species alters the environment most? Which occupies a niche most different from all others? It doesn’t end there.

Beaver in Potter PondThe beaver (link is PDF) is a classic example of a keystone species, a species that makes the entire ecosystem work. Beavers change the environment around them. They create ponds, alter vegetation, and change the geology over time. A food web analysis wouldn’t turn them up, but a natural historian couldn’t miss it.

Hunting pushed beavers to near to extinction through much of their range by around 1900. Reintroductions and reduced hunting has allowed them to expand throughout their historic range, to the point that farmers consider them pests.

Now imagine the best way to promote conservation under two circumstances.

1) How could you best recover beavers? End the commercial trade in beaver pelts. Diminish hunting pressure, and, if needed, provide legal protection for beaver dams for a limited time.

2) How could you best recover an arbitrary species which declined as beaver ponds disappeared? Reduce harvest? No. Reintroduce? No. Create fake beaver dams? I guess. Help beavers recover? Definitely.

The point is, there are two basic causes behind species declines.

  • Hunting
  • Habitat reduction/modification

A lot fits into category two, but let’s just leave it be for now. We can broaden our understanding of hunting to include live capture for the pet trade and increased predation by natural or introduced predators. We can exclude broad scale poisoning and accidental killing of some kinds. Ecologists would call this an increase in species specific mortality.

The Endangered Species Act and things like CITES (the international treaty restricting trade in endangered and threatened species) work great for species under unique mortality pressure. You restrict the commercial activity that endangers the species and it recovers on its own. Perfect.

Bald eagles, beavers, alligators, and egrets are a few of the species that have recovered after hunting was restricted or ended. These are species that have broad habitat requirements and high enough fecundity (birth rates).

The attack on the Endangered Species Act (see this Congressional whitepaper) seems to be focussing on the claim that

only 12 of these 1304 species have been recovered in the Act’s history, according to the Fish and Wildlife Service?s data on de-listed species. That is an abysmal, less than 1 percent rate of species recovery. The FWS’s statistics show that only 30 percent of species are ?stable? and only 9 percent are ?improving.?

This statistic seems horrible, but actually isn’t. It’s what my old roommate Ben Estep called a ?ban the fire department? argument.

  • Fires used to destroy houses.
  • Fire departments are supposed to put out fires.
  • Fires still destroy houses.
  • Fire departments don’t work.
  • Let’s abolish fire departments.

No one would take that seriously, but smart people will see nothing wrong with the same attack on ESA.

Most endangered species aren’t being hunted to death. Those species that have recovered did so because a specific cause of mortality could be alleviated. Most species aren’t under that sort of threat. In fact, most species probably are in some sort of honest-to-god danger.

Why? Most species are rare. The distribution of range size is lognormal, meaning the most likely range size is small, but there is a long ?tail,? leaving ever fewer species with larger ranges. There are several theories that might explain this, but it is a very general pattern, whatever causes it. Species with small ranges are almost certain to have small ecological niches (a small set of combinations of conditions in which the population of a species increases in density). The headline: Most species naturally occur in very small, restricted areas.

Being hunted sucks, but it takes extraordinary hunting pressure to obliterate a species. Consider the sort of hunting passenger pigeons sustained for decades before they went extinct. What really hits so many species (even passenger pigeons) is habitat loss.

What species do you expect would be most quickly harmed by generalized habitat destruction? On average, species with small ranges or very specific requirements will have the greatest percentage of their range destroyed.

So the population of the US grows, and the amount of land modified by humans (e.g., under cultivation or used for housing) increases even faster. This will impact a lot of species that need habitat that’s easy to turn into farms, houses, or strip malls. Since their density was never much above any safety margin, even full recovery might not merit de-listing.

But guaranteeing that native habitats be protected would do a lot. Many of these species are neither ecologically significant (e.g., nothing specializes on eating them or being pollinated by them), nor aesthetically important. If they go extinct, some people will feel shitty, but a serious argument can be advanced that it’s a less serious loss than others might be. Preserving the habitat is the valuable goal, and the fact that a local endemic is threatened is often the only legally actionable claim to be advanced against development. Once a species is listed as endangered, critical habitat is declared, and the species is safe.

Would it be less strenuous on all parties if it were possible to skip the intermediate step of listing an arbitrary species and just get certain habitat declared ?critical.? Critical to the aesthetic, religious and scientific values of the human community?

If such a law existed, the devil would be in the details, and the ESA would still have an important place, especially in controlling the importation of endangered species. I’ll get into more of what I think an endangered habitats law should look like later.

?Don’t worry about the government? by Talking Heads from the album 77 (1977, 3:01).

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