I'm back. For a little bit longer, at least.
The plight of the monarch butterfly, whose population has been steadily dwindling, is something I've been following on this blog for awhile. Two weeks ago, an international organization designated the iconic insect as being endangered:
One of the most popular and recognizable insects is at risk of extinction, according to a global organization focused on conservation and sustainability.
The International Union for Conservation of Nature has added the migratory monarch butterfly to its Red List of Threatened Species as endangered, the group said in a release Thursday.
"It is difficult to watch monarch butterflies and their extraordinary migration teeter on the edge of collapse, but there are signs of hope," said Anna Walker, a species survival officer for invertebrate pollinators at the New Mexico BioPark Society who works in partnership with the IUCN Species Survival Commission.
The monarch is the only butterfly known to make a two-way migration like birds, according to the US Forest Service. Every winter, monarchs that live in the eastern part of North America migrate to the Sierra Madre mountains in Mexico, and those in the west migrate to the coastal regions of California, according to the federal agency. Those migrations have been a spectator event in the past.
There are a couple of important things to note here:
- First, this designation from the IUCN does not make the monarch a legally endangered and protected species in the United States. Only the US Fish and Wildlife Service has the power to declare the monarch endangered under the Endangered Species Act. This is an action the FWS considered about a year and a half ago; they deferred for the time being.
- Second, this designation only applies to the subspecies which migrates annually between Mexico and the United States and Canada. The monarch butterfly species as a whole is widely distributed across the Americas and is not at risk.
The IUCN estimates the native population of monarch butterflies has shrunk by between 22% and 72% over the past decade, and the western population has declined by 99.9% between the 1980s and 2021 -- putting it at the greatest risk of extinction.
Destruction of habitat and rising temperatures fueled by the climate crisis are increasingly threatening the species, the IUCN said.
When they are caterpillars, monarchs feed exclusively on the leaves of milkweed, according to the National Wildlife Federation.
But droughts have limited the growth of milkweed, and increased temperatures have triggered earlier migrations, the IUCN said. There has also been an increase in the use of glyphosate herbicide -- particularly on corn and soybean crops -- that has caused a severe milkweed decline in the United States.
For what it's worth, the amount forest area occupied by the migratory monarch during its winter hibernation in Mexico - a proxy for its overall population - has been holding relatively steady in the 2-3 hectare range in five of the past six winters. Hopefully this suggests that the population decline that the IUCN cited in its decision to add the insect to its Red List has at least stabilized.
In any case, the IUCN's designation should be a wake-up call: the monarch migration is truly an amazing natural wonder; we would fail both the butterflies and ourselves if we allowed it to end under our watch.
If you want to help, consider creating a monarch waystation that provides both milkweed host plants for caterpillars as well as nectar plants for adults.