Tiny Trackers Follow Monarch Butterflies on Their Long Migration
The U.S. Fish and Wildlife Service is fitting monarchs with lightweight Bluetooth trackers to follow their fall migration south to overwintering habitat.
Monarch butterfly migration is fully under way this fall, and scientists are following it in a new way. On October 20, the U.S. Fish and Wildlife Service described how it is fitting monarch butterflies with lightweight Bluetooth trackers as they migrate south toward overwintering habitat. The work is part of Project Monarch, a collaboration involving more than 20 partner organisations in the United States, Canada, Mexico and Cuba.
One tagged monarch, named Mona, began migration in northwestern Minnesota and flew in a direct line to the Missouri River in central South Dakota, then shifted south, with a last detection in the Big Bend area of southwestern Texas. Another monarch, nicknamed Chew, left northeastern Utah on September 2 and was detected on October 11 in Santa Catarina, Nuevo Leon, Mexico. That was the first radio-tracked evidence of a monarch from west of the Rocky Mountains joining eastern monarchs on the journey to Mexico.
How monarch butterfly migration tracking works in practice
Monarch butterfly migration tracking works through a network of receivers and phones. The BluMorpho tag, built by Cellular Tracking Technologies in Cape May, weighs about 60 milligrams, light enough for a butterfly to carry without stopping it from flying. When a tagged butterfly passes near a receiver station or a phone running the Project Monarch app, the signal is logged, giving researchers a point on the map and a time.
The eastern monarch population has dropped by more than 80 percent since the mid-1990s, and the western population by about 95 percent, according to figures cited in reporting on the project. Habitat loss, insecticide exposure and climate change are among the pressures facing monarchs. Tracking helps scientists understand which habitats matter most along the route, from milkweed-rich breeding grounds in the north to nectar-rich stopover sites in Texas and the oyamel fir forests in Mexico where colonies settle.
Source: U.S. Fish and Wildlife Service
