Climate Change

Climate change is a primary threat to biodiversity, but for many species, we still lack information required to assess their relative vulnerability to changes. Climate change vulnerability assessment (CCVA) is a widely used technique to rank relative vulnerability to climate change based on species characteristics, such as their distributions, habitat associations, environmental tolerances, and life-history traits. However, for species that we expect are vulnerable to climate change yet are understudied, like many amphibians, we often lack information required to construct CCVAs using existing methods. We used the CCVA framework to construct trait-based models based on life history theory, using empirical evidence of traits and distributions that reflected sensitivity of amphibians to environmental perturbation. We performed CCVAs for amphibians in 7 states in the north-central USA, focusing on 31 aquatic-breeding species listed as species of greatest conservation need by at last 1 state. Because detailed information on habitat requirements is unavailable for most amphibian species, we used species distributions and information on traits expected to influence vulnerability to a drying climate (e.g., clutch size and habitat breadth). We scored species vulnerability based on changes projected for mid-century (2040?2069) from 2 climate models representing “least-dry” and “most-dry” scenarios for the region. Species characteristics useful for discriminating vulnerability in our models included small range size, small clutch size, inflexible diel activity patterns, and smaller habitat breadth. When projected climate scenarios included a mix of drier and wetter conditions in the future, the exposure of a species to drying conditions was most important to relative rankings. When the scenario was universally drier, species characteristics were more important to relative rankings. Using information typically available even for understudied species and a range of climate projections, our results highlight the potential of using life history traits as indicators of relative climate vulnerability. The commonalities we identified provide a framework that can be used to assess other understudied species threatened by climate change.

This data release contains information collected during surveys for chorus fogs (Pseudacris maculata), wood frogs (Lithobates sylvaticus) and tiger salamanders (Ambystoma mavortium) conducted in Rocky Mountain National Park (1986 – 2022) by the U.S. Geological Survey. Survey methods included visual encounter and aural surveys, and dip netting. Data collected between 1986 and 1994 focused on named water bodies in Rocky Mountain National Park. Data collected between 1995 and 1999 are from focal monitoring sites as well as sporadic surveys of other wetlands. Data collected between 2000-2002 represent repeated surveys conducted between 1986 and 1994 (e.g., park-wide surveys of named water bodies) and additional surveys of unnamed waterbodies. Data collected after 2002 were collected under an occupancy framework. Sites were identified within pre-defined catchments using the National Wetlands Inventory Database to locate potential amphibian breeding habitat (e.g., ponds, ephemeral wetlands). If appropriate sites were encountered in the field and were not indicated on National Wetland Inventory databases (https://www.fws.gov/program/national-wetlands-inventory/metadata), they were added as incidental sites. Waterbodies were visited and surveyed at least two times during the amphibian active season (May and mid-August). Water bodies were surveyed for all life stages of amphibians.

For species with complex life histories, climate change can have contrasting effects for different life stages within locally adapted populations and may result in responses counter to general climate change predictions. Using data from two, 14-year demographic studies for a North American montane amphibian, Cascades frog (Rana cascadae), we quantified how aspects of current climate influenced annual survival of larvae and adult stages and modeled the stochastic population growth rate (?s) of each population for current (1980-2006) and future periods (2080s). Climate drivers of survival for the populations were similar for larvae (i.e. decreases in precipitation lead to pond drying and mortality), but diverged for terrestrial stages where decreases in winter length and summer precipitation had opposite effects. By the 2080s, we predict one population will be in sharp decline (?s = 0.90),while the other population will remain nearly stable (?s = 0.99) in the absence of other stressors, such as mortality due to disease. Our case study demonstrates a result counter to many climate envelope predictions in that stage-specific responses to local climate and hydrology result in a higher extinction risk for the more northern population.