An article appearing in The Hill reports, "Number of monarch butterflies migrating to Mexico for winter is on the decline."
"Eastern monarch butterflies once migrated to a wintering site in Mexico that spanned 45 acres of forest, according to the World Wildlife Fund (WWF). But their population during the winter months has been on the decline for the last 25 years. Most recently, the presence of monarch butterflies in Mexico has dropped 22 percent in only one year, from 7.02 acres to 5.46 acres, according to recent reports cited by the WWF.
"Eastern monarch butterflies travel up to 2,800 miles from as far as Canada and New England to their winter sites in Mexico forests using a combination of the magnetic pull of the planet and the position of the sun. This is one of the longest migrations of insect species known to scientists."