Scientists are now using new ultralight radio tags to track the movements of monarch butterflies in Santa Cruz, California. The project is a collaboration between the Xerces Society for Invertebrate Conservation, Point Blue Conservation Science, California State Parks, and Santa Cruz County Parks.
According to a news release from the Xerces Society, “Scientists are now tracking the movements of imperiled monarch butterflies in Santa Cruz with the help of new ultralight radio tags.” These tags weigh less than a tenth of a gram and were attached to individual monarchs at Natural Bridges State Beach, Lighthouse Field State Beach, and Moran Lake County Park. Additional tagging has also taken place further south on the Central Coast.
Senior conservation biologist Emma Pelton explained: “The tagged butterflies will help us understand when and where monarchs move among overwintering sites and the surrounding areas. These details will help us identify where to prioritize conservation of western monarch habitat, as well as provide the most accurate picture of their home range to date.”
Western monarch populations have experienced significant declines since the 1980s. The Xerces Society stated that “Protecting and restoring overwintering habitat is a crucial part of the species’ recovery plan.“
The ultralight tag developed by Cellular Tracking Technologies weighs just 0.06-0.07 grams—comparable to about two grains of rice.
David James, an entomologist at Washington State University who has led paper-tag tracking efforts for over a decade, described radio-tagging as a major advance: “Radio-tagging is a game changer not only for monarch migration studies but also for insect movement research. For the first time, we can follow large insects like monarchs and bumblebees over long (or short) distances.” He added that this technology could help answer questions about migratory routes that remain unresolved: “We suspect that the majority [of Idaho’s monarchs] head due south from Idaho, perhaps ending up in Mexico. Radio-tagging offers us the opportunity to solve this mystery! We will bring more details of this exciting new project and how you can be involved early next year!”
James noted that these radio tags work with most smartphones equipped with Bluetooth and location services: “The radio tag utilizes most smartphones with enabled Bluetooth and location services as passive receivers, allowing unprecedented spatial and temporal tracking in near-real time.”
Previous tagging efforts have shown that many monarchs from Washington migrate to California for overwintering. However, little is known about where Idaho’s population spends winter.
