Has the Eastern Red-backed Salamander (Plethodon cinereus) Declined in Ontario?

Abstract

Amphibians are known to be declining around the world. Although often only reported for frogs, declines among salamanders are also known to be occurring. In Ontario, for example, citizen science monitoring indicates the Eastern Red-backed Salamander (Plethodon cinereus) has not been found in the last 20 years in many areas where it was historically known to occur. To test whether this decline is real or the result of lack of recent observations, we conducted targeted surveys in 25 grid squares with no recent records of the species and confirmed the presence of the Eastern Red-backed Salamander in 84% of these squares. It made up 90% (183 of 202) of all six species of salamanders encountered and was also the first salamander species detected in 90% of the squares. The median number of cover objects needed to detect a species was 34 (range 1–145) for Eastern Red-backed Salamanders, 129.5 (range 34–204) for Blue-spotted Salamanders (Ambystoma laterale), and 154 (range 6–187) for Spotted Salamanders (Ambystoma maculatum), and these detection rates differed significantly (H = 9.46, P < 0.01). Our study suggests that Eastern Red-backed Salamanders have not declined. We caution researchers using citizen science data that a lack of sightings of a “cryptic species” does not mean a species has declined.