Each year from late July through September, monarch descend in huge numbers on the flowers in the Habitat Garden. These individual monarchs, which weigh about as much as a paperclip, fly from Maine to Mexico, around 2,500 miles to spend the winter in monarch preserves. While at the garden, volunteers carefully place uniquely numbered tags on the hindwing of monarchs. The date the butterfly was tagged and its sex are recorded on datasheets that are sent to Monarch Watch. In Mexico, volunteers recover tagged monarchs and report the tag numbers to Monarch Watch.  In 2020, a monarch tagged at Valentine Farm was recovered in Mexico!

In 2022, 338 monarchs were tagged.