Buzz
In the autumn of 1968, residents of the eastern United States witnessed a natural phenomenon like no other: grey squirrels, in vast numbers, migrating from the forests, traversing mountains, rivers, and highways.
Newspapers reported sightings of squirrels swimming across bodies of water, many succumbing to the currents. In some areas, conservation officers noted collecting roadkill at a staggering rate of one squirrel per mile, with countless more perishing from hunger.
But where were these squirrels headed? And what was the cause of this strange migration?
The reason behind this squirrel migration was surprisingly simple: They ran out of food. After a year of abundant acorns and chestnuts in 1967, the squirrel population surged. But when the following season yielded fewer nuts, the squirrels had no choice but to venture in search of richer forests.
The most thorough account of the migration comes from Vagn Flyger, a wildlife biologist and emerging squirrel expert working as a game officer in Maryland. In his paper titled "The 1968 Squirrel 'Migration' in the Eastern United States" [PDF], Flyger recounts being contacted by a colleague who drove from Maine to Maryland on September 13, noticing an unusually high number of squirrels dead on the road. Within a week, Flyger also heard from the Smithsonian’s Center for Short-Lived Phenomena (yes, it was a real institution, though short-lived, operating from 1968 to 1975), which had been tracking reports from North Carolina.
Other regions saw similar phenomena. The New York State Conservation Department collected 122 squirrel specimens from highways near Albany and received reports of many drowning in the Hudson River. A September 28 article in the Journal News of White Plains was ominously titled "Squirrels Invading Lower Hudson Valley." On October 6, The Tennessean published a piece where the state’s fish and game commissioner Bob Burch marveled at the “almost unbelievable number of squirrels,” and announced the bag limit would be raised “from six to twelve bushytails per day” to “help hunters keep this valuable resource from going to waste.”
North Carolina seemed to be ground zero. The Asheville Citizen Tribune, in a September 17 article titled "Starvation, Cars, Killing Squirrels by the Thousands" covered a wildlife resources commission meeting where managers from across the state shared grim accounts. One reported squirrels “pouring” out of the Smoky Mountains, swimming across Fontana and Cheoah Lakes. Another mentioned counting 40 dead squirrels on a 20-mile stretch of road near Asheville. The story, titled "Squirrels Starving in Smokies’ Area," even made it into The New York Times on September 22.
In his investigative paper (published by the Natural Resources Institute), Flyger described traveling to North Carolina and, with a small team from the University of Georgia, setting up a makeshift “laboratory” in a motel room in Boone to examine specimens shot by game wardens and collected from highways.
The autopsies revealed no abnormalities. There were no signs suggesting the squirrels were traveling toward a specific destination—like north or west. However, Flyger discovered through discussions with others and his own observations that 1967 had seen an abundance of acorns, leading to a population boom of baby squirrels in 1968. By fall, as the first litter of the year began to leave the nest, food sources were too scarce to sustain them.
Flyger’s theory is still valid today, according to John Koprowski, a leading squirrel expert and professor at the University of Arizona’s School of Natural Resources and the Environment.
“A good chestnut year provides a tremendous amount of food, but when the year is poor, that food supply disappears. You can imagine animals having to move around—especially at a time when roads were fewer, and forests were more continuous,” Koprowski explained to mental_floss.
Koprowski clarifies that this was not a true migration but rather an emigration—“a one-way movement from a location.”
“It’s likely a last-resort strategy,” Koprowski suggests. “It really does seem to be a reaction to local conditions.”
It turns out that 1968 wasn’t the first instance of grey squirrels migrating by the thousands due to scarce resources. After reading Flyger’s paper as an undergraduate at Ohio State, Koprowski further explored the phenomenon and discovered evidence of similar—and even larger—squirrel emigrations in the 19th century.
For example, in Texas in 1857, a harsh mid-spring cold snap devastated crops and vegetation across the state, including newly budding nut trees, sparking a squirrel exodus. One account details a young man named Henry Garrison Askew, traveling by horse and carriage near Dallas, who described how the horses were startled by a disturbance in the tall prairie grass. He and his family watched in awe as thousands of squirrels crossed the road—some even running over the horses and through the carriage—in a line that reportedly took half an hour to pass.
In his 1846 book Viviparous Quadrupeds of North America, John Bachman writes about squirrel emigrations from that era, where squirrels would “gather in different districts of the far Northwest, and, in irregular groups, instinctively head eastward. Mountains, cleared fields, narrow bays of lakes, or vast rivers were no match for them. Onward they came, consuming everything in their path, destroying the corn and wheat fields of farmers … ”
Koprowski notes that these historical accounts, filled with adjectives like marvelous and incredible, don’t give a clear idea of numbers. “They were often rich with descriptive language, but not as quantitative as we would expect today.”
Koprowski suggests that given the landscape of the time, it’s likely the numbers involved could have reached into the hundreds of thousands or even millions. “It’s difficult for us to fully grasp the abundance of food and the density of squirrels back then,” he says.
Could such large-scale squirrel emigrations happen again? Unlikely, says Koprowski. “First of all, we’ve altered the forests significantly with fragmentation,” he explains. “There simply isn’t as much suitable habitat for squirrels or the nut-bearing trees they’ve historically relied on.”
But it's fun to imagine. “It’s such a unique phenomenon,” he adds. “You think to yourself, ‘Wow, that's pretty amazing.’”
