Many recognize Monarch butterflies on garden flowers in spring as they arrive, or in late summer, on their way south to Mexico or beyond. Our region is on the western edge of eastern monarch migration, while a western migration is along America’s west coast. Interest in Monarchs and their wellbeing can be a marker of the concern for the environment of pollinators and other wildlife.
We plant what the seed catalogs call “pollinator plants,” many of which are native to our region, to attract butterflies. We look for the first Monarch caterpillars on milkweed and butterfly weed that we plant to ensure they have food and shelter and use as few pesticides as possible in the garden.
Year to year, with variable spring weather and variable growing conditions for the plants that attract Monarchs, it is hard to be sure if Monarchs are doing well by the number we see in our own gardens.
The non-profit Monarch Joint Venture is a national partnership of agencies and programs to conserve Monarch butterfly migration. They have just released a review of research from June 2019 to August 2020, found on their website at www.monarchjointventure.org. See their report for a more informative review of the studies.
Among their recent findings that may lead to more research:
- From tagged Monarchs in southeastern Arizona that migrated to Mexico and California, it appears that there is some connectedness between eastern and western Monarch migration pathways.
- Climate change may “limit reproductive capacity of breeding monarchs” and may be a “driver of habitat loss in the Mexican overwintering grounds.”
- New invertebrate Monarch predators have been documented in Midwestern grasslands.
- In the wild, “only 1.4% of Monarch eggs survive to the 5th instar stage,” just before chrysalis.
- A higher density of urban and midwestern conservation grasslands have milkweeds for habitat than previously thought.
- Captive Monarchs, reared in captivity and released into the wild, seem not able to complete the migration.
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Monarch butterflies are celebrities here. A neighborhood near where I lived in college is Monarch Grove because so many monarch butterflies swarm the naturalized blue gum and red gum trees. However, the swarming is very unnatural. Eucalypti are not native here. Monarch butterflies who swarm them are ignoring native plant species that rely on them for pollination.