Confirmation bias perpetuates century-old ecological misconception: Evidence against 'Secretive' behavior of Eastern Spadefoots

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Despite a 1944 publication questioning the misconception that Eastern Spadefoots (Scaphiopus holbrookii) and other Scaphiopodidae are 'secretive' outside of rain-induced migration and breeding aggregations, confirmation bias has perpetuated this fallacy. As a result, S. holbrookii is one of the least studied frogs in the United States. Amassing a large postmetamorphic dataset, we examined the misconception that S. holbrookii are secretive outside of breeding aggregates or optimal environmental conditions. Using eyeshine spotlighting, we conducted transect, mark-recapture, and haphazard spotlighting surveys in Virginia and Rhode Island forests. Although no breeding events or migration occurred during this study, we detected thousands of postmetamorphic S. holbrookii in Virginia and dozens in Rhode Island, the majority of which were subadults-a demographic category severely overlooked in the literature. These results are in direct contradiction with historical surveys of our sites. Spotlighting was an efficient method of detecting S. holbrookii eyeshine in forests, which were easily differentiated from arthropod eyeshine. Minimal effort was needed to detect the presence of S. holbrookii in Virginia and Rhode Island, even though both states have different climates and S. holbrookii densities. We also discovered a previously undetected population in Rhode Island. Scaphiopus holbrookii of all postmetamorphic size classes emerged regularly from burrows, even with no precipitation. We discuss how confirmation bias and lack of appropriate field methods for nonbreeding life history stages has fueled the misconception that S. holbrookii are difficult to find outside of optimal weather conditions, which has hindered progress studying the ecology and conservation of this species.

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Journal of Herpetology