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Rodent indent not self-evident: a case of mistaken identity of the ‘Chicago Rat Hole’
Journal article   Open access   Peer reviewed

Rodent indent not self-evident: a case of mistaken identity of the ‘Chicago Rat Hole’

Michael C. Granatosky, Gabby Guilhon, Noah D. Chernik, Stratos J. Kantonis, Christine J. Lee and Edwin Dickinson
Biology letters (2005), v 21(10), p20250343
Oct 2025
PMID: 41089057
url
https://doi.org/10.1098/rsbl.2025.0343View
Published, Version of Record (VoR) Open

Abstract

Animal Behaviour
The ‘Chicago Rat Hole’ is a remarkable full body impression ostensibly created by a brown rat (Rattus norvegicus) crossing fresh concrete in Chicago’s Roscoe Village that became a viral sensation. While the public attributed the mark to a brown rat, no formal analysis had been conducted to confirm its identity. Using clear anatomical landmarks, we compared measurements from the ‘Chicago Rat Hole’ to eight sympatric rodent species using univariate and multivariate analyses. Univariate tests showed no significant differences in snout-to-tail length, head width, tail-base width or third digit length between the imprint and members of the genus Sciurus (i.e. tree squirrels). Discriminant function analysis indicated a 98.67% likelihood that the ‘Chicago Rat Hole’ was a squirrel, with classifications split between the eastern grey squirrel (50.67%) and the fox squirrel (48.00%). Given local population densities, an eastern grey squirrel likely represents the most parsimonious species-level match. This investigation underscores the challenges of attributing a trace to the tracemaker. While we acknowledge the playful spirit of this investigation, our broader aim is to highlight that scientific inquiry begins with curiosity and observation: qualities that are not exclusive to professional scientists, but accessible to anyone with an interest in understanding the natural world.

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Collaboration types
Domestic collaboration
International collaboration
Web of Science research areas
Biology
Ecology
Evolutionary Biology
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