In recent years, growing public awareness of the monarch’s plight has led to a surge in captive rearing. But scientists and conservation groups have warned against such practices, arguing that insects housed in dense conditions would be more susceptible to diseases that they could then spread to their wild peers. Regardless, “this study shows that captive releases are unlikely to help wild monarchs,” says Karen Oberhauser from the University of Wisconsin-Madison. “It won’t make that much difference if they can’t migrate and become a normal part of the population.”

    That’s not to say that all captive-reared monarchs are incompetent migrators. Last year, around 700 commercially bred individuals were tagged and released at a San Antonio festival; five of these were later found at overwintering sites in Mexico. “But there’s a population-level difference,” says Kronforst. “Some individuals might be able to respond correctly, but most do not.”

    The team also admits that they studied insects from just one commercial breeder. Though they suspect that other captive-reared individuals would behave similarly, they can’t say that for sure. “That’s an important caveat,” says Anurag Agrawal from Cornell University. “Nonetheless, they’re bringing scientific data to the table on a hot-button point in monarch conservation.”

posted 148 days ago