Dozens of monarch butterflies descended on the prairie at the Peggy Notebaert Nature Museum Tuesday, feasting on the nectar of purple ironweed flowers and golden compass plant blossoms.⁠ ⁠ The iconic orange and black visitors were part of an annual spectacle: the late summer migration of millions of monarchs from as far north as Canada to wintering grounds in the mountains of Mexico, a journey of up to 3,000 miles.⁠ ⁠ “It’s already underway,” said Allen Lawrance, associate curator of entomology at the Peggy Notebaert Nature Museum. “They are passing through.” Lawrance predicted that the migration will continue in the Chicago region for the next week or two.⁠ ⁠ Recently listed as endangered, monarchs have suffered from habitat depletion in general and the loss of wild milkweed in particular. Populations have shrunk by between 22% and 72% over the last decade, with threats including logging in Mexico and California, herbicide and pesticide use, and climate change.⁠ ⁠ Click the link in our bio to learn how you can watch the migration and how you can help the endangered monarch butterfly. (Erin Hooley and Antonio Perez / Chicago Tribune)⁠