{"id":18539,"date":"2019-11-09T02:37:27","date_gmt":"2019-11-09T02:37:27","guid":{"rendered":"https:\/\/www.lifeandnews.com\/articles\/?p=18539"},"modified":"2019-11-10T12:39:26","modified_gmt":"2019-11-10T12:39:26","slug":"how-do-we-know-when-a-species-at-risk-has-recovered-its-not-just-a-matter-of-numbers","status":"publish","type":"post","link":"https:\/\/www.lifeandnews.com\/articles\/how-do-we-know-when-a-species-at-risk-has-recovered-its-not-just-a-matter-of-numbers\/","title":{"rendered":"How do we know when a species at risk has recovered? It’s not just a matter of numbers"},"content":{"rendered":"

H. Resit Akcakaya<\/a>, Stony Brook University (The State University of New York)<\/a><\/em><\/p>\n

Around the world, animals and plants are disappearing at alarming rates. In May 2019, a major U.N. report warned that around one million species<\/a> were at risk of extinction \u2013 more than at any other time in human history.<\/p>\n

Conservation scientists like me<\/a> focus on predicting and preventing extinctions. But we see that as an essential first step, not a final goal. Ultimately, we want species to recover.<\/p>\n

The challenge is that while extinction is easy to define, recovery is not. Until recently, there was no general definition of a \u201crecovered\u201d species. As a result, some species recovery plans are much less ambitious than others, and scientists don\u2019t have a common yardstick for recognizing conservation successes.<\/p>\n

To address this challenge, the International Union for the Conservation of Nature<\/a>\u2019s Species Survival Commission \u2013 the world\u2019s largest network of conservationists \u2013 is developing a Green List of Species<\/a> to highlight species recovery. This tool will complement the well-known Red List<\/a>, which highlights endangered species.<\/p>\n

While the Red List focuses on extinction risk, the Green List will measure recovery and conservation success. As a member of the team charged with making the Green List a practical conservation tool, I see it as a way of measuring the impact of conservation and communicating conservation success stories, as well as learning from failures.<\/p>\n

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Defining recovery<\/h2>\n

To know how much conservation has accomplished, and to encourage ambitious conservation goals, we need an objective way to measure progress toward a species\u2019 recovery. Studies of recovery plans developed under the U.S. Endangered Species Act show that some plans consider a species recovered even if its population remains the same or shrinks<\/a> during the recovery effort. A standard definition of recovery would prevent such inconsistencies and encourage wildlife managers to aim higher.<\/p>\n

Conservation scientists have long attempted to identify different facets of species recovery<\/a>. Reviewing these efforts, our team came up with several requirements for considering a species fully recovered.<\/p>\n

As I explain with an international group of colleagues in a new study, one key idea is that populations of the species should be \u201cfunctional<\/a>.\u201d By this we mean that they are able to perform all the roles that the species is known to play in ecosystems where it exists. This may seem like an obvious measurement, but in fact, some species that are considered to be \u201crecovered\u201d in the U.S. fail this test.<\/p>\n

\"\"<\/a>
The Kirtland\u2019s Warbler was declared recovered in the U.S. in 2019, but will still rely on land managers to maintain stands of jack pine where it nests and control parasitic cowbirds that prey on it.<\/span>
\nJoel Trick\/USFWS<\/a>, CC BY<\/a><\/span><\/figcaption><\/figure>\n

What\u2019s your function?<\/h2>\n

Each species has many kinds of ecological functions. For example, bees help plants reproduce by pollinating them<\/a>. When birds and bats eat fruits and later excrete the seeds<\/a>, they help forests regenerate.<\/p>\n

Similarly, when salmon swim upstream to spawn and then are consumed by bears and other predators, that process moves essential nutrients<\/a> from the oceans up into rivers and forests. And when flammable grasses burn in the U.S. Southeast, they fuel fires that maintain longleaf pine forests<\/a>.<\/p>\n

All these critical functions are possible only when enough members of the key species are present. Put another way, keeping a species alive is not enough \u2013 it also is essential to keep its functions from going extinct.<\/p>\n