2017-09-07. Scientists say decline in monarch butterflies brings risk of extinction.

posted Sep 10, 2017, 9:55 PM by Alan Gould
By Peter Fimrite, San Francisco Chronicle. For GSS Losing Biodiversity chapter 1. Excerpt: Western monarch butterflies, which crowd trees along the California coast every winter and flush them with color, have declined so dramatically since the 1980s that the species will likely go extinct in the next few decades if nothing is done, scientists said Thursday in a population study of the treasured creatures. ...according to the report published in the journal Biological Conservation. “We believe there were at least 10 million butterflies in many of the years during the 1980s,” said Cheryl Schultz, an associate professor of biological sciences at Washington State University and the lead author of the study. “It’s gone down from 10 million to 300,000. That’s why we were so shocked. We did not expect it to be that sharp of a decline.” ...The decline is similar to that seen among the more abundant eastern monarchs, which spend their winters in Mexico before heading back across the United States and settling as far north as Canada. ...Eastern monarchs have declined more than 90 percent since 1996, when scientists estimated there were 1 billion nesting in the trees. Last winter, 78 million eastern monarchs were counted in Mexico, compared with 100 million the year before.... http://www.sfgate.com/bayarea/article/Scientists-say-decline-in-monarch-butterflies-12181328.php