Environmental Suitability and Thermal Tolerance of Blanchard's Cricket Frog (Acris blanchardi)

Date of Award

8-15-2026

Degree Name

M.S. in Biology

Department

Department of Biology

Advisor/Chair

Maggie Hantak

Abstract

Amphibian populations have experienced substantial global declines in recent decades. Various factors of decline have been investigated such as habitat loss, disease prevalence, and pesticide use, but climate change has become a relevant variable in the past several decades. Blanchard’s cricket frog (Acris blanchardi), a small, semi-aquatic, member of the family Hylidae, was once abundant throughout the United States, ranging from as far south as Texas and Northern Mexico and extending north to Michigan and Ontario, Canada. Blanchard’s cricket frog (Acris blanchardi) has been in decline throughout the northern extent of their range since the late 1970s. Despite past efforts investigating various possible drivers of the decline, there are still no clear drivers of the species current distribution. To address this shortcoming, we used ecological niche modelling (ENM) to assess historical, current, and future environmental suitability for A. blanchardi. Maximum entropy (MaxEnt) modeling with species occurrence data and bioclimatic variables sourced from WorldClim revealed declines throughout the northern distribution of A. blanchardi around the start of the first reported declines (1977). Future projections showed a decrease in the overall suitability in the southern United States, and an increase in suitability in the Northern states. Variables highly correlated with A. blanchardi suitability were the warmest temperature of the warmest month, elevation, and precipitation seasonality. This research expands our understanding of A. blanchardi distribution and the variables influencing their suitability, allowing us to better conserve this species as the environment changes. The onset of global climate change has increased the variability and frequency of extreme temperatures. These changes in temperature may be difficult for amphibians to cope with due to ectothermic constraints. Blanchard’s cricket frog (Acris blanchardi) has been in decline throughout the northern extent of their range since the late 1970s. Various studies have investigated the cause of this decline, but few have examined the effects of climate change. Little is known about the thermal capacity of A. blanchardi and whether plasticity exists in these traits. In this study, we collected data on the critical thermal maximum (CTmax) and minimum (CTmin), of A. blanchardi across seasons and across ontogeny to determine whether acclimation or life history plays a role in thermal tolerance. Our study was conducted from early spring to late fall of 2025 in southwest Ohio. We found that thermal tolerance changes throughout the year, with CTmin increasing throughout the season, and CTmax increasing from spring to summer, and then decreasing in the fall. Additionally, we found that tadpoles tolerate more extreme temperatures than juveniles and adults. This study serves as a basis for the thermal biology of A. blanchardi and presents implications for amphibians in the face of climate change.

Keywords

Biology, Climate Change, Museum Studies, Organismal Biology, Wildlife Conservation, Wildlife Management

Rights Statement

Copyright 2026, author

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