Apparent widespread decline of the Boreal Chorus Frog (<em>Pseudacris maculata</em>) in eastern Ottawa

Abstract

The Boreal Chorus Frog (Pseudacris maculata) was once common in the eastern Ottawa area. To assess its current status, we conducted auditory surveys at 184 wetlands in 2011 and 2012. Boreal Chorus Frogs were heard at only five (2.7%) of the surveyed sites. These five sites were spatially aggregated, with only 0.5-7.5 km between any two sites. Sites occupied by Boreal Chorus Frogs in eastern Ottawa were surrounded by significantly greater agricultural cover (at 1.0-, 1.5-, and 2.0-km radii), less forest cover (1.0-and 2.0-km radii), and less wetland cover (1.5-and 2.0-km radii) than occupied sites in western Ottawa. Sites in eastern Ottawa that were apparently unoccupied were surrounded by significantly greater agricultural cover (only at the 2.0-km radius), similar forest cover (all radii), and less wetland cover (all radii) compared with occupied sites in western Ottawa. Boreal Chorus Frog populations are commonly subject to extirpation resulting from stochastic events. The reduced wetland cover in eastern Ottawa may be accompanied by reduced wetland connectivity, making recolonization of wetlands difficult or impossible. Our data do not show whether wetland connectivity has been reduced, but future research should address this important topic.

A 91% decline in a common anuran in an otherwise stable amphibian community inferred from 17 years of rapid road surveys

“…This is problematic, as historic declines may have occurred or be well underway before monitoring is readily justifiable (Harding et al., 1998), resulting in misguided assumptions relating to historical population sizes (Dayton et al., 1998). In countries such as Canada, where few amphibian populations have been monitored prior to 1990, many studies indicate that populations have not declined (Seburn & Gunson, 2012; Silva et al., 2003; Seburn, Gunson & Schueler, 2014; Smith et al., 2014). While these populations appear healthy, it is possible that declines have previously occurred and that we are monitoring a new baseline; this is known as ‘shifting baseline syndrome’ (Dayton et al., 1998).…”

Twenty‐nine years of population dynamics in a small‐bodied montane amphibian

“…Given the likelihood of significant changes in climate, potential for disease, reports of population declines (Seburn et al. ), and a limited understanding of demographic processes in chorus frogs, significant declines are plausible, and their security is not certain.…”

“…Furthermore, reduced genetic diversity relative to the chorus frog species complex (Moriarty-Lemmon et al 2007) suggests potential risk (e.g., inbreeding depression) if isolation of populations increases. Given the likelihood of significant changes in climate, potential for disease, reports of population declines (Seburn et al 2014), and a limited understanding of demographic processes in chorus frogs, significant declines are plausible, and their security is not certain.…”

Follow-up ecological studies for cryptic species discoveries: Decrypting the leopard frogs of the eastern U.S.

“…The recent split of trilling chorus frogs ( Pseudacris spp.) and identification of a new species [ 13 , 14 ], for example, prompted local status assessments based on the newly identified species limits and demonstrated sharp declines in one of the contained species [ 15 , 16 ]. Confirmation of cryptic diversity in cavefish [ 17 ] was followed by conservation status assessments that showed many lineages to be of conservation concern [ 18 ].…”