To save the "alarmingly low" population of monarch butterflies in North America, a University of Guelph professor and ecologist says Canada, the U.S., and Mexico need to co-operate on a wide-scale conservation plan. 

Ryan Norris and his colleagues have studied monarch butterflies in North America and developed a conservation strategy outlined in a paper recently published in the journal Current Biology.

"In the last 15 years, [monarch butterfly populations have] been at alarmingly low numbers," N…