WASHINGTON (AP) – Monarch butterflies are now listed as endangered because of fast dwindling populations in North America. The International Union for the Conservation of Nature announced the designation on Thursday for the orange-and-black butterflies. The group estimates that populations have declined between 22% and 72% over a decade. After wintering in central Mexico, the butterflies migrate north to Canada. They breed new generations along the way that begin the return trip at the end of summer. The butterflies are imperiled by loss of habitat and increased use of herbicides and pesticides for agriculture, as well as climate change.