The viral ‘Chicago Rat Hole’ captivated the internet in 2024, but a new scientific analysis published in Biology Letters now confirms with 98.67% certainty that this iconic imprint was the work of a squirrel, not its namesake, offering a fascinating deep dive into urban ecology and trace fossil analysis.
Few urban curiosities have sparked as much internet fervor and community engagement as the famed “Chicago Rat Hole.” This animal-shaped imprint in a Roscoe Village sidewalk became an overnight sensation, drawing pilgrims, leaving offerings, and even hosting weddings. But as with many urban legends, its true origin remained shrouded in mystery until now. A groundbreaking study has scientifically debunked the popular belief, revealing the sidewalk’s true artist was almost certainly a squirrel.
From Local Oddity to Global Phenomenon: The Rat Hole’s Viral Journey
The “rat hole” is believed to have existed for two to three decades, a quiet fixture in the Roscoe Village neighborhood. Its rise to global fame began abruptly on January 6, 2024, when Chicago artist and comedian Winslow Dumaine posted a photo of the imprint on X, proclaiming his pilgrimage to the site. His tweet resonated, transforming the humble sidewalk mark into an internet sensation, affectionately dubbed “Splatatouille” by some during a public naming contest.
Almost overnight, the site became a hotspot, attracting curious tourists and devoted fans who left offerings ranging from coins to shots of Malört. The fervor reached a peak with reports of couples getting engaged and even married beside the quirky landmark. This outpouring of public affection also brought challenges; complaints from neighbors about the constant traffic led to attempts by some to fill the impression with plaster. Ultimately, in April 2024, city workers removed the slab of sidewalk for preservation, transporting it to the City Hall-County Building. A plaque commemorating the “rat hole” still marks its original location.
The Scientific Inquiry: Unpacking the Evidence
The lingering question—what animal truly made the imprint—sparked the curiosity of Dr. Michael Granatosky, an assistant professor of ecology and evolutionary biology at the University of Tennessee, Knoxville. Driven by the opportunity to engage the public with nature, Granatosky and his colleagues from the New York Institute of Technology College of Osteopathic Medicine and the University of Calgary undertook the first scientific analysis of the imprint. Their findings, published in the journal Biology Letters, were decisive.
Since the original sidewalk slab had been removed, the researchers meticulously studied online photographs of the “rat hole,” using coins left by visitors as scale bars to accurately measure various features of the impression. These measurements were then compared against museum specimens of animals commonly found in the Chicago area, including:
- Brown rat
- House mouse
- Eastern grey squirrel
- Eastern chipmunk
- Muskrat
- White-footed mouse
- Fox squirrel
- Southern flying squirrel
The initial analysis quickly eliminated many possibilities. The presence of clear outlines for arms, legs, and a tail immediately ruled out birds, snakes, frogs, and turtles. Further examination of claw outlines narrowed the field to mammals. However, the creature’s long forelimbs, distinct third digits, and hind paws proved too large for a typical rat, mouse, or chipmunk. Instead, these measurements fell squarely within the ranges for Eastern grey squirrels, fox squirrels, and muskrats.
Why a Squirrel? The Key Factors
The research team presented several compelling arguments favoring the squirrel hypothesis:
- Arboreal Anatomy: Squirrels possess longer digits, adapted for climbing, which aligns with the elongated imprints observed.
- Nocturnal vs. Diurnal Activity: Cement is typically wet during the day. Squirrels are diurnal (active during the day), while rats are nocturnal. This timing strongly favors a squirrel encounter with fresh concrete.
- Lack of Tracks: The absence of paw prints leading to or from the impression suggests the animal either misjudged a leap or fell from a branch into the wet cement. Squirrels are known for such aerial maneuvers.
- Tail Impression: While the imprint’s tail appeared rat-like, the fine, bushy hair of a squirrel’s tail is unlikely to leave a deep, well-defined impression, thus explaining the seemingly slender tail mark.
Considering the abundance of Eastern grey squirrels in Chicago, the study concluded a 98.67% likelihood that a squirrel was responsible, with a 50.67% chance it was specifically an Eastern grey squirrel.
The Impact: Renaming, Lore, and Urban Ecology
The researchers propose rechristening the landmark the “Windy City Sidewalk Squirrel,” a name they argue is more fitting for its scientific origins. However, this change is unlikely to stick with the public or the city. Ryan Gage, director of public affairs for the Chicago Department of Streets and Sanitation, stated, “With great respect to the scientific community, the Rat Hole is part of Chicago lore now… We aren’t so sure people will be swayed by the study to refer to it as anything else.”
Winslow Dumaine, the comedian who sparked its viral fame, readily accepts the scientific findings. Yet, he believes the “Rat Hole” moniker holds a deeper resonance. As he explained, “Marilyn Monroe wasn’t her real name, but Norma Jean still captured the heart of the world… The rodent responsible for the Chicago Rat Hole does not need to be a rat to accomplish the very same.” He suggests the name evoked a kinship with the “discarded,” allowing people to celebrate a reviled creature, much like themselves amidst a challenging world.
This study highlights the importance of urban ecology—the intricate interactions between animals, plants, and humans within city environments. As Dr. Seth Magle, senior director of the Urban Wildlife Institute at Chicago’s Lincoln Park Zoo, pointed out, such research “captures the public’s imagination” and draws attention to the nature thriving in plain sight. It also serves as a cautionary tale for paleontology, demonstrating the complexities of interpreting trace fossils even in near-perfect modern scenarios, as noted by lead author Granatosky.
The Enduring Appeal of Urban Trace Fossils
The “Chicago Rat Hole,” now definitively identified as a “Windy City Sidewalk Squirrel” imprint, remains a powerful symbol of urban wildlife and human fascination. Its story is a testament to how accidental marks in concrete can spark cultural movements and inspire scientific inquiry. The original slab, now removed and safely stored by the Chicago Department of Streets and Sanitation, awaits a permanent home where it can continue to be observed and appreciated by the public, perhaps now with a deeper understanding of its true, squirrel-shaped legacy.
Whether you call it the “Rat Hole” or the “Windy City Sidewalk Squirrel,” its impact on the public consciousness and its contribution to our understanding of urban ecology are undeniable. It serves as a playful yet profound reminder of the vibrant, often hidden, life that thrives in our cities.
