Monarch butterflies migrating through Minn. despite population decline

A monarch butterfly in California
In this 2010 file photo, a monarch butterfly sits in a flower in Los Angeles. The Monarch is famous for its southward migration and northward return in summer in the Americas which spans the life of three to four generations of the butterfly.
GABRIEL BOUYS/AFP/Getty Images

Monarch butterflies are in their migration through Minnesota right now, but reports of declining numbers worry conservation experts.

From MPR News earlier this summer:

Scientists blame extreme weather in the southern states for a massive die-off of the Monarch this year. Its absence may also be sending messages about the environment's health. Suburban sprawl, mowing and farm chemicals have reduced the population of milkweed, the only plant where Monarchs place eggs.

A generation of Monarchs may have been lost, says Elizabeth Howard, director and founder of the Monarch research group Journey North.

Karen Oberhauser, professor of conservation biology at the University of Minnesota, joins The Daily Circuit to discuss how this year's migration is offering clues to explain the declining population.