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Scientists Use the “Half-Life” of a Species to Motivate Conservation Efforts

By Gustave Axelson
Eastern Meadowlarks have declined 75% since 1970. Photo by Corey Hayes via Birdshare.

From the Spring 2017 issue of Living Bird magazine. Subscribe now.

The global population of Eastern Meadowlarks has declined by 75 percent since 1970. And the future looks worse. According to a new report, North America stands to lose half of what’s left of meadowlarks before the year 2040.

“Half-lives” is the morbid new metric debuted in a re­port released by Partners in Flight, a supergroup of 150 bird conservation nonprof­its and government agen­cies throughout the Western Hemisphere.

Coming on the heels of a State of North America’s Birds report that calculated more than a third of the continent’s bird species were in need of urgent conservation action, the half-lives statistic is yet another attempt by ornithol­ogists to quantify and com­municate to the public about the ongoing, tremendous loss of birdlife.

Since 1970, a suite of 46 landbird species have lost more than 1.5 billion breed­ing individuals in their total continental population—a staggering decline that, ac­cording to the report, “could disrupt the structure and function of ecosystems.”

For this report, scien­tists calculated the half-life of declining species by esti­mating the number of years before an additional 50 per­cent of their global popula­tion is lost, if current trends continue. More than a dozen species had half-lives of fewer than 34 years, meaning they would lose half their remnant populations by 2050.

“The half-life metric con­veys a sense of urgency. How long before the abundance of birds that we all enjoy will be cut in half?” says Bob Ford, the Partners in Flight nation­al coordinator. “When most of us see those numbers, we want to change them.”

Cornell Lab conservation scientist Ken Rosenberg, a lead author on the report, adds that the half-life calcula­tions surprised even him.

“The window for revers­ing declines and preventing extinctions is narrower than we thought,” Rosenberg says.

The Cornell Lab

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