The monarch butterfly may not be endangered, but their migration is
SAVANNAH, Ga. (WSAV) — The University of Georgia (UGA) said that their new research may have answered the biggest question plaguing butterfly researchers.
UGA said that a big question when discussing the monarch butterfly is, why are the wintering populations declining while breeding populations are stable ?
The study published by the Proceedings of the National Academy of Sciences suggested that monarchs are dying off during their fall migration south to Mexico, UGA said.
"The monarchs are increasingly failing to reach their winter destinations," said Andy Davis, lead author of the study and an assistant research scientist in UGA's Odum School of Ecology . "Either they're losing their ability to migrate or they're losing their will to migrate."
What's leading to the monarch migration decline?
Migrating monarchs don't fly at night and spend their evenings in bunches on trees or shrubs, known as roosts. UGA said that researchers found that roost sizes have declined by as much as 80%, with these losses increasing from north to south along the migration route.
The researchers found that the timing of the migration hasn't changed and, if anything, the route has become greener and warmer over time since greener, warmer locations should have led to larger roost populations.
"How do you say that the monarch butterfly is going extinct in the winter while they're perfectly healthy in the summer?" said William Snyder , co-author of the study and a professor of entomology in UGA's College of Agricultural and Environmental Sciences . "This paper fills in that gap by saying the problem is that fall migration."
Instead, they said that researchers documented steady, dramatic declines in roost sizes over the migration route that were largely due to two main culprits.
The first is the increasing prevalence of a debilitating monarch parasite, which has increased tenfold since the early 2000s, they said. This increase corresponds with increased plantings of nonnative milkweeds– the only plant on which monarchs can lay their eggs and their caterpillars can feed —throughout the flyway.
The second possible driver is the release of captive-reared butterflies by well-meaning people who are hoping to help the monarchs, UGA said.
"All of the evidence we have shows that when monarchs are reared in a captive environment, either indoors or outdoors, they're not as good at migrating," Davis said.
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How can people help 'save the monarchs'?
UGA said that while it's typically well-intended, many of the things people do to try to help, such as planting nonnative milkweeds or raising monarchs for release in captivity, may actually be harming the monarch population by interfering with their ability to migrate long distances.
"One of the best things people can do to ensure that the monarchs are as robust and healthy as possible is basically just leave the caterpillars alone in your backyard," Davis said. "Resist the temptation to bring them inside and protect them because it seems like Mother Nature does a better job at creating really healthy, robust migrators than we do."
Published in PNAS, the study was co-authored by Jordan Croy , a postdoctoral associate in UGA's College of Agricultural and Environmental Sciences .
