Scientists studying monarch butterflies have traditionally focused on two sources for their decline – winter habitat loss in Mexico and fewer milkweed plants in the Midwest.
New research conducted by Michigan State University and published in Proceedings of the National Academy of Sciences, however, shows that a critical piece of the butterfly’s annual cycle was missing – the fall migration. By focusing on this southerly trek, as well as changing the scale at which winter populations are examined, scientists reveal a wider, more-accurate spectrum of threats that have contributed to the monarch population’s downward trend.
“Getting accurate monarch counts in the summer is tough,” said Sarah Saunders, former MSU integrative biologist and the study’s lead author. “Finding them in the fall, though, is nearly impossible as they’re moving hundreds of miles daily.”
Read more at Michigan State University
Image by Vikramjit Kakati from Pixabay