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- Sep 30, 2011
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Long-term declines in the overwintering eastern population of North American monarch butterflies are significantly increasing their likelihood of becoming extinct over the next two decades, according to Scripps Institution of Oceanography at UC San Diego and U.S. Geological Survey research published today.
The new study, available in the journal Scientific Reports, found that the Eastern migratory monarch population declined by 84 percent from the winter of 1996-1997 to the winter of 2014-2015. Using this information, the study demonstrated that there is a substantial chance – 11 to 57 percent – of quasi-extinction over the next 20 years. A quasi-extinct population is one with so few remaining individuals left that recovery is impossible. While the remaining individuals may survive for a short time, the population as a whole will inevitably go extinct.
"Because monarch numbers vary dramatically from year to year depending on weather and other factors, increasing the average population size is the single-most important way to provide these iconic butterflies with a much-needed buffer against extinction,” said Scripps biologist Brice Semmens, the lead author of the study who studies extinction risk in fish and other animal populations.
Semmens said that as an example of this variability, just after the analysis concluded, the World Wildlife Fund Mexico and partners reported a large increase in monarch numbers since last year. However, this increase was followed by a recent winter storm that may have adversely affected the population. The authors emphasized that although one good winter – as occurred this year – is positive news, higher average monarch numbers are necessary for reducing the long-term risk of quasi-extinction.
Eastern monarch butterflies at risk of extinction unless numbers increase
It looks as if they are off to good start though.
The new study, available in the journal Scientific Reports, found that the Eastern migratory monarch population declined by 84 percent from the winter of 1996-1997 to the winter of 2014-2015. Using this information, the study demonstrated that there is a substantial chance – 11 to 57 percent – of quasi-extinction over the next 20 years. A quasi-extinct population is one with so few remaining individuals left that recovery is impossible. While the remaining individuals may survive for a short time, the population as a whole will inevitably go extinct.
"Because monarch numbers vary dramatically from year to year depending on weather and other factors, increasing the average population size is the single-most important way to provide these iconic butterflies with a much-needed buffer against extinction,” said Scripps biologist Brice Semmens, the lead author of the study who studies extinction risk in fish and other animal populations.
Semmens said that as an example of this variability, just after the analysis concluded, the World Wildlife Fund Mexico and partners reported a large increase in monarch numbers since last year. However, this increase was followed by a recent winter storm that may have adversely affected the population. The authors emphasized that although one good winter – as occurred this year – is positive news, higher average monarch numbers are necessary for reducing the long-term risk of quasi-extinction.
Eastern monarch butterflies at risk of extinction unless numbers increase
It looks as if they are off to good start though.
