MEXICO CITY (AP) – The number of monarch butterflies that showed up at their winter resting grounds decreased about 53 per cent this year, Mexican officials said on Friday. Some activists called the decline “heartbreaking”, but the Mexico head of the World Wildlife Fund said the reduction “is not alarming”.
WWF Mexico Director Jorge Rickards said the previous year’s large numbers were “atypical” and the monarchs had returned to their average population levels of recent years. The government commission for natural protected areas said the butterflies’ population was “stable”, even though they covered only 2.8 hectares this year. That was down from 6.05 hectares the previous year.
Because the monarchs cluster so densely in pine and fir trees, it is easier to count them by area rather than by individuals. “During the most recent wintering season the norm has been for the butterflies to cover an average of about three hectares,” Rickards said.