Habitat suitability and connectivity modeling reveal priority areas for Indiana bat (Myotis sodalis) conservation in a complex habitat mosaic

Ashleigh B Cable,Mark A Davis,Tara C Hohoff,Steven J Taylor,Jill L Deppe,Joy M O’Keefe

doi:10.1007/s10980-020-01125-2

Abstract

ContextConservation for the Indiana bat (Myotis sodalis), a federally endangered species in the United States of America, is typically focused on local maternity sites; however, the species is a regional migrant, interacting with the environment at multiple spatial scales. Hierarchical levels of management may be necessary, but we have limited knowledge of landscape-level ecology, distribution, and connectivity of suitable areas in complex landscapes.ObjectivesWe sought to (1) identify factors influencing M. sodalis maternity colony distribution in a mosaic landscape, (2) map suitable maternity habitat, and (3) quantify connectivity importance of patches to direct conservation action.MethodsUsing 3 decades of occurrence data, we tested a priori, hypothesis-driven habitat suitability models. We mapped suitable areas and quantified connectivity importance of habitat patches with probabilistic habitat availability metrics.ResultsFactors improving landscape-scale suitability included limited agriculture, more forest cover, forest edge, proximity to medium-sized water bodies, lower elevations, and limited urban development. Areas closer to hibernacula and rivers were suitable. Binary maps showed that 30% of the study area was suitable for M. sodalis and 29% was important for connectivity. Most suitable patches were important for intra-patch connectivity and far fewer contributed to inter-patch connectivity.ConclusionsWhile simple models may be effective for small, homogenous landscapes, complex models are needed to explain habitat suitability in large, mixed landscapes. Suitability modeling identified factors that made sites attractive as maternity areas. Connectivity analysis improved our understanding of important areas for bats and prioritized areas to target for restoration.

Highlights

Bats are critical components of functioning ecosystems and, in the United States of America (USA), are at risk from many factors
While simple models may be effective for small, homogenous landscapes, complex models are needed to explain habitat suitability in large, mixed landscapes
Connectivity analysis improved our understanding of important areas for bats and prioritized areas to target for restoration

Summary

Introduction

Bats are critical components of functioning ecosystems and, in the United States of America (USA), are at risk from many factors. Bats migrating to summer maternity areas are likely to encounter fragmented habitat (Carter et al 2002; USFWS 2007), increased wind energy development (Arnett and Baerwald 2013; Roscioni et al 2013), decreased prey availability via agricultural pesticide application (IDNR 2017 and Sanchez-Bayo and Wyckhuys 2019), and exposure to environmental contaminants (O’Shea and Clark 2002), all of which may impact survival. The Indiana bat (Myotis sodalis) is an insectivorous species listed as ‘‘Endangered’’ under the USA Endangered Species Act (ESA) and ‘‘Near Threatened’’ on the International Union for Conservation of Nature’s Red List of Threatened Species. Females form large maternity colonies, Landscape Ecol (2021) 36:119–137 usually under the bark of dead trees, and remain in the area, rearing young until migrating back to hibernacula in the fall (Guthrie 1933). Myotis sodalis are philopatric and return to maternity areas (Gumbert et al 2002), suggesting that maintaining suitable maternity habitat enhances fitness (USFWS 2007)

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