Demographic consequences of climate change and land cover help explain a history of extirpations and range contraction in a declining snake species

Abstract

Developing conservation strategies for threatened species increasingly requires understanding vulnerabilities to climate change, in terms of both demographic sensitivities to climatic and other environmental factors, and exposure to variability in those factors over time and space. We conducted a range-wide, spatially explicit climate change vulnerability assessment for Eastern Massasauga (Sistrurus catenatus), a declining endemic species in a region showing strong environmental change. Using active season and winter adult survival estimates derived from 17 data sets throughout the species' range, we identified demographic sensitivities to winter drought, maximum precipitation during the summer, and the proportion of the surrounding landscape dominated by agricultural and urban land cover. Each of these factors was negatively associated with active season adult survival rates in binomial generalized linear models. We then used these relationships to back-cast adult survival with dynamic climate variables from 1950 to 2008 using spatially explicit demographic models. Demographic models for 189 population locations predicted known extant and extirpated populations well (AUC = 0.75), and models based on climate and land cover variables were superior to models incorporating either of those effects independently. These results suggest that increasing frequencies and severities of extreme events, including drought and flooding, have been important drivers of the long-term spatiotemporal variation in a demographic rate. We provide evidence that this variation reflects nonadaptive sensitivity to climatic stressors, which are contributing to long-term demographic decline and range contraction for a species of high-conservation concern. Range-wide demographic modeling facilitated an understanding of spatial shifts in climatic suitability and exposure, allowing the identification of important climate refugia for a dispersal-limited species. Climate change vulnerability assessment provides a framework for linking demographic and distributional dynamics to environmental change, and can thereby provide unique information for conservation planning and management.

Delaying conservation actions matters for species vulnerable to climate change

“…Our approach builds on the demographic models of Pomara et al. (), who found that historic range‐wide declines in EMR were associated with demographic sensitivities to both winter drought and summer flooding.…”

“…Previous research highlights the importance of environmental drivers of EMR adult active season survival rates including winter minimum temperature, summer cumulative precipitation, anthropogenic land cover, and winter drought (Pomara et al., ). Winter (November‐March) minimum temperature (mean temperature of the coldest month) and summer (June‐August) maximum precipitation (cumulative precipitation of the wettest month) were summarized annually from 1950 to 2010 at a spatial resolution of 0.5° from the Climate Research Unit (CRU) Time‐Series (TS) v.3.22 dataset (Harris, Jones, Osborn, & Lister, ).…”

“…We parameterized a population‐level range‐wide demographic model for EMR where fecundity and survival estimates were combined to parameterize a females‐only, age‐based with 11 classes, stochastic population model across the geographical distribution of EMR (Table , Faust, Szymanski, & Redmer, ; Pomara et al., ). Survival rates varied by population ( n pop = 226) annually from 1965 to 2100.…”

Synergistic effects of climate and land cover: grassland birds are more vulnerable to climate change

“…As an example, Pomara et al (2014) found that accurately predicting climate change vulnerability and population persistence for Eastern Massasauga (Sistrurus catenatus) rattlesnakes, a threatened wetland-dependent species, relied on quantifying the interaction of extreme events (e.g., drought) and habitat loss resulting from residential encroachment. How species respond to climate change across a heterogeneous landscape consisting of varying amounts of habitat is a critical aspect of accurately assessing climate change vulnerability for any given species.…”

Evaluation of the Consistency of MODIS Land Cover Product (MCD12Q1) Based on Chinese 30 m GlobeLand30 Datasets: A Case Study in Anhui Province, China

“…[1][2][3][4][5][6]. Nevertheless, it has always been a difficult problem to derive such a parameter, especially at national, continental and even global scales, since the emergence of remote sensing.…”