Public Release: 

Monitoring data confirm key predictions about extinction

Blackwell Publishing Ltd.

Long-term monitoring of wild populations is a central tool for conserving species. Sometimes, such monitoring follows populations as they actually go extinct. In a paper now published online in Ecology Letters, Fagan & Holmes analyse the final decline of 10 populations of vertebrate animals, each monitored over at least 12 years, to provide the first empirical confirmation of two theoretical predictions about the extinction process.

The analysis demonstrates, first, that the size of a population and its time-to-extinction are related by a logarithmic (rather than linear) function, confirming a key prediction from the theory of stochastic population dynamics. Second, two lines of evidence suggest that these ten extinction-bound populations collectively exhibit dynamics akin to those theoretically proposed to occur in "extinction vortices", in which key aspects of a populations' dynamics (e.g., mean and variance in the rate of change) deteriorate as extinction approaches. Together, these results provide key empirical insights into extinction dynamics, which is critical for improved management of rare species.

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