Monarch butterfly numbers drop to new lows

Few monarchs in eastern Canada this year

The number of monarch butterflies now on their migration to Mexico appear to to be at record lows. A monarch feeds on silky red milkweed, in a monarch way station as part of Monarch Watch, a continental effort to create backyard habitats for the butterflies along their migratory routes. (Steve Smedley/The Pantagraph/Associated Press)

Monarch butterflies appear headed for a perhaps unprecedented population crash, according to scientists and monarch watchers who have been keeping tabs on the species in their main summer home in Eastern and Central North America.

There had been hope that on their journey north from their overwintering zone in Mexico, the insects’ numbers would build through the generations, but there’s no indication that happened.

Only a small number of monarchs did make it to Canada this summer to propagate the generation that has now begun its southern migration to Mexico, and early indications are that the past year’s record lows will be followed by even lower numbers this fall.

Elizabeth Howard, the director and founder of Journey North, a citizen-scientist effort that tracks the migrations of monarchs and other species, says one indicator for the robustness of the monarchs is the number of roosts they form in late August and September, something Journey North monitors throughout the migration periods.