How Many Animals Are Too Many?

NEW YORK, NY— Setting population target levels for wildlife species can be a tricky business–especially when there are 18 distinct approaches currently in use.

All 18 are cataloged in a new paper appearing in the journal Bioscience authored by Wildlife Conservation Society ecologist Dr. Eric Sanderson.

Sanderson says “minimum viable populations,” the goal commonly used by wildlife managers aiming for self-sustaining populations, should be seen as “the beginning, not the end, of conservation.”

“Having animals acting like animals in the fullest sense, seems the standard conservationists should seek, whether it’s bison on the Great Plains or Asia’s forests with tigers and their prey,” he said.

Sanderson proposes a simpler, four-tiered system to measure conservation success.

Once “demographic sustainability” has been achieved, he says, the next level of conservation effort should aim next for “ecological functionality,” which means a species will serve its role in ecosystems.

“Sustainable human use” is the next tier, where animals are sufficient for human use – either for consumption or for viewing and enjoyment.

Sanderson’s highest standard for animal populations is achieving “historical baselines” where species are restored to a time when humanity had less impact on the planet than it does today.

Sanderson writes that achieving this goal can be difficult due to lack of baseline data, though well-managed protected areas, with all the species present, can provide the examples that scientists and managers need.

“People want much more from wild animals than to see them just persist,” he said. “We want animals to interact with their environment, evolve over time, be beautiful and useful to us, and to satisfy ethical teachings regarding respect for nature.”