Monarchs report their locations via… cell phone?
New technology allows butterflies to tagged with devices that report time and location
Who knew a Monarch butterfly could borrow a cell phone to check in with friendly people he met on his journey?
That is essentially what happens now that new technology has reduced the weight of a radio-pulse tag to less than half a gram. Those tags use Bluetooth technology to send information back to the researchers in the U.S. and Canada, including Jennifer Weber, Ph.D. '25, and Shawn Kurtzman from the Conservation Management Institute, to collect far more data than has ever been available about the paths and speed of Monarch butterflies as they migrate from a vast range in continent’s temperate areas to nature preserves in Mexico and Central America.
International calls are welcome, as some of the butterflies tagged in Virginia are now in Mexico.
Weber gave some of the Monarchs names and keeps up with their perilous migratory journeys. Sneezy, tagged here in the New River Valley in September, was detected in Mexico on Oct. 17. Addison and Sleepy, also part of the mountain cohort, checked in from Texas but now seem to be travelling outside of range of cell service. Two other recent visitors to Virginia Tech, Hahn and Sandman, are now in Alabama and South Carolina, respectively. Orion and Walker were in Georgia, dealing with tropical storm Isaias, before heading west again.
Thomas is the real traveller. Tagged in Fort A.P. Hill near Fredricksburg, he was last detected in Mississippi, then pinged again a thousand miles away in southern Mexico.
"We figured he would follow the Gulf Coast and make his way to the wintering grounds," Weber said. "Imagine our shock when he pinged yesterday at lunchtime all the way across the gulf. His latest ping put him a little bit east of a city named Coatzacoalcos, well south of the wintering grounds."
Weber said Thomas and a few other radio tagged monarchs were picked up by a swirling storm system and deposited on the Mexican coast.
To say Monarchs are checking in with cellphones is not hyperbole. The new tags emit a pulse detectable by Bluetooth-enabled smartphones, vehicles, and cellular towers which send a signal through a background function to the researchers to create a continuous, real-time map.
"It’s citizen science, but crowd-powered," Weber said.
No information about the device itself is sent — just the tag number and location. It also means a Monarch flying over wilderness could go days without being located, leaving Weber to wonder if the tag stopped working, fell off, or the butterfly perished.
Kurtzman said the estimated survival rate is 25 to 28 percent.
Following a flight path at hundreds of data points reveals micro-level behaviors, such as whether monarchs utilize highway corridors, how they react to major weather disruptions, and where they pause to feed on available nectar along their route.
Weber and Kurtzman outfitted 35 Monarchs with pulse tags and follow their path to winter quarters. The cost of the radio-pulse tags is still high enough that most butterflies are tagged with a small sticker on a wing that includes contact information for anyone who found it. This message-in-a-bottle strategy returns data from a tiny percentage of Monarchs.
The CMI researchers tagged Monarchs on federal land around military installations in three Virginia locations — the Radford Arsenal for a mountain population; Fort A.P. Hill for a Piedmont population; and Oceana Naval Air Station and Joint Base Langley-Eustis to identify a coastal population. Monarchs tagged on the Tech campus were included in the mountain cohort. By deploying tags across mountain, Piedmont, and coastal locations, researchers want to determine whether monarchs from different geographic regions in Virginia follow the same migration corridors to Mexico or take distinct paths, such as heading south into Florida.
A butterfly that flits around doesn’t seem to be moving rapidly in any specific direction, but just two hours after being tagged in September on the Virginia Tech campus, one Monarch was flying near the New River in Giles County, having crossed two ridgelines on its way west.
The research will be used by Project Monarch, a collaborative initiative, along with Monarch Joint Venture and the Xerces Society for Invertebrate Conservation, two nonprofits working to understand and preserve Monarchs, a threatened species. Researchers from dozens of universities and research groups are partnering with these agencies to reveal how these insects navigate around or through challenging areas throughout eastern North America.
“We're all kind of throwing our data in the same pot,” Weber said. “Hopefully, that data will be available for anyone who needs it so we can help these little guys.”
Learning more about the migratory routes will guide land management choices in the future. Whether it’s a large expanse of federal land or a yard owned by a butterfly aficionado, encouraging plants than benefit Monarchs is ecologically important. Milkweed, goldenrod, thistle, and wingstem are a few of the species Monarchs need.
“You can't just provision the caterpillars and do nothing for the adults, because milkweed doesn't last into the fall,” Weber said “Then we start relying on the wingstem, we rely on the thistle, we rely on the goldenrod. So having a wide variety of plants and plants that provision them at every portion of the year is super important.”