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Squirrel Swarms: 1968 Mystery Solved by Weather
18 Oct
Summary
- An estimated 20 million squirrels migrated in 1968.
- A study linked squirrel movements to acorn crop failures.
- Unusual weather patterns in 1967 preceded the migration.
In the autumn of 1968, an extraordinary event unfolded as an estimated 20 million eastern grey squirrels embarked on a massive migration across parts of the northeastern United States. This dramatic movement, which saw squirrels crossing highways and even attempting to swim across bodies of water, has long been a subject of scientific curiosity.
Recent investigations, including a study published in Forest Ecology and Management, have shed light on the underlying causes. Researchers analyzed acorn production in North Carolina between 1962 and 1973, correlating it with weather data. They discovered a complex relationship where warmer spring and summer conditions appeared to reduce acorn yields in several oak species.
Specifically, the summer of 1967 experienced record low temperatures across the northeastern United States. This unusual weather, occurring after a potentially bountiful acorn harvest in a previous year, likely led to a significant shortfall in food availability for the squirrel population. Such a drastic reduction in their primary food source would have prompted increased competition and driven large numbers of squirrels to seek sustenance elsewhere, explaining the widespread irruption.
