The decline of milkweed may not be the main factor driving monarch butterflies toward oblivion, according to a new study by Cornell University scientists. Weather, habitat fragmentation and dwindling sources of nectar in the autumn are also critical, the new study reports.
“Thanks to years of data collected by the World Wildlife Fund and citizen-scientists across North America, we have pieced together the monarch life cycle to make inferences about what is impacting the butterflies,” said Cornell University Prof. Anurag Agrawal.
Steep regional population declines are leading the species toward the brink
While there has been some recent good news about short-term prospects for monarch butterflies, a new study led by scientists with theU.S. Geological Survey and the Scripps Institution of Oceanography at UC San Diego warns that the eastern population of the species could become extinct within a few decades.
This year’s count estimated that 56.5 million monarchs are currently gathered in Mexico for the winter, up from last year’s lowest ever total of 34 million. But that’s still more than 80 percent below the 20-year average and down 95 percent from numbers tallied in the mid-1990s. Near-perfect conditions during breeding season helped bolster the numbers this year. Continue reading “Biodiversity: Monarchs bounce back, still need help”→
GMO crops blamed for significant 10-year drop in population numbers
By Summit Voice
SUMMIT COUNTY —A decades-long downward trend in Monarch butterfly numbers is expected to continue this year, with reports from the World Wildlife Fund and other sources indicating there may be almost one-third fewer butterflies making the northward flight from Mexico this spring and summer.
This year’s steep decline may, in part, be due to last summer’s severe drought in Texas, which resulted in less food for the showy insects as they traveled south. But year-to-year fluctuations don’t hide the overall long-term trend of population decline.
“The latest information shows that Monarchs will be down from 25 to 30 percent this year, and that has been part of a disturbing trend the last few years,” said Craig Wilson, a senior research associate in the Center for Mathematics and Science Education and a long-time butterfly enthusiast.