Study: Number of monarch butterflies in California declined by 86 percent in one year | SFGate.com

‘The population of western monarchs in California was already low before the most recent count, having declined by an estimated 97 percent since the 1980s. The species will likely go extinct in the next few decades if nothing is done to save them, a 2017 study by Washington State University researchers found.

Source: Study: Number of monarch butterflies in California declined by 86 percent in one year | SFGate.com