Saving the monarch butterfly—biologist explains population census discrepancies
August 3, 2017
Monarch butterfly populations have taken a nosedive over the last 20 years, according to researchers who monitor the number of butterflies that spend the winter in Mexico every year. But organizations of citizen scientists in the United States who conduct yearly censuses of monarchs in state parks and other locations in the summer have reported no consistent dip in the number of butterflies they see.
This discrepancy has led some to challenge the widely accepted belief that loss of milkweed on the U.S. landscape has driven the decline of the species. However, an ISU researcher and colleagues have found an explanation for the difference between the overwintering numbers and the summer census findings. And their explanation, published recently in the academic journal PLOS ONE, bolsters the view that loss of milkweed, the only plant on which monarchs will lay eggs, has forced monarch populations to fall.
Read more at:
https://phys.org/news/2017-08-monarch-butterflybiologist-population-census-discrepancies.html#jCp
