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THE USE OF RIGHT OF WAYS BY PRIMARY BURROWING CRAYFISHES IN THE OUACHITA MOUNTAINS ECOREGION OF ARKANSAS BY CODY MARTIN RHODEN THESIS Submitted in partial fulfillment of the requirements for the degree of Master of Science in Natural Resources and Environmental Sciences in the Graduate College of the University of Illinois at Urbana-Champaign, 2016 Urbana, Illinois Master’s Committee: Adjunct Assistant Professor Christopher A. Taylor, Adviser Associate Professor Robert L. Schooley Adjunct Assistant Professor Michael Dreslik Assistant Professor William E. Peterman, The Ohio State University ABSTRACT Roadside ditches can harbor beneficial and detrimental attributes for animal persistence. I sought to determine if roadside ditches could be preferred by two narrowly endemic primary burrowing crayfish species, Fallicambarus harpi and Procambarus reimeri. To investigate this interaction, I collected habitat data, locality information, and tested computer generated habitat models for these two species in the Ouachita Mountains Ecoregion (OME) of western Arkansas in the spring of 2014 and 2015. My first objective was to determine the fine-scale habitat preferences of F. harpi and P. reimeri in relation to their occurrence in roadside ditches. My analysis revealed these species to be habitat specialists, preferring open habitat with a low- herbaceous, wet microhabitat; similar to habitat found in roadside ditches. My second objective was to determine the ability of habitat models to accurately predict the occurrence of these two crayfishes across the OME. To investigate this objective, I used the locality data gained in the first field season to construct species distribution models using the program Maxent. I then used the species distribution model as a guide to sample for both crayfish species across the OME. My analysis revealed that species distribution models, specifically Maxent, are a suitable tool for analyzing and discovering new populations of both F. harpi and P. reimeri. My concentrated search efforts resulted in a documented range expansion of both species in the OME. My third objective was to assess the conservation status of both F. harpi and P. reimeri. Using the locality data that I collected over the two years of study (2014 and 2015), I was able to determine F. harpi and P. reimeri are constrained geographically but relatively stable throughout their range. I discovered new populations of both species, moderately expanding the range of F. harpi (<100 km2) and P. reimeri by a larger distance (>1000 km2). I conclude that the microhabitat of roadside ditches can be beneficial to the persistence of these two narrowly endemic habitat specialists in the Ouachita Mountains Ecoregion in Arkansas. ii To my grandparents, Bill and Gloria Emrich, and my parents, Steve and Kara Rhoden, who gave me the gift of higher education iii ACKNOWLEDGEMENTS I would like to thank my advisor, Dr. Christopher Taylor for all of his guidance and support throughout my graduate studies. The knowledge and patience that he has shown me have been invaluable to my education and development as a biologist. I would also like to thank Dr. Bill Peterman for sharing his extensive knowledge in modeling and statistical analysis, without which my results would be much less informative. Also thanks to Drs. Mike Dreslik and Bob Schooley for assistance with the initial study design and statistical analysis. I am grateful for those who helped me in the field and with permitting, namely Brian Wagner, Josh Seagraves, Allison Fowler, Andrea Daniel, Benjamin Thesing, and Justin Stroman. Special thanks to Sarah Tomke and Dan Wylie for their relenting assistance in digging mudbugs in the ditches of Arkansas with me. Finally, I would like to thank my friends and family for their unwavering support and encouragement during my graduate research. iv TABLE OF CONTENTS CHAPTER 1: GENERAL INTRODUCTION ........................................................................... 1 CHAPTER 2: ROADSIDES AS PREFERRED HABITAT FOR TWO NARROWLY ENDEMIC CRAYFISHES ........................................................................................................ 12 CHAPTER 3: FIELD VALIDATION OF MAXENT MODELING OF TWO NARROWLY ENDEMIC CRAYFISHES ............................................................................... 40 CHAPTER 4: HABITAT ASSESSMENT AND RANGE UPDATES FOR TWO RARE ARKANSAS BURROWING CRAYFISHES: FALLICAMBARUS HARPI AND PROCAMBARUS REIMERI ...................................................................................................... 69 SUMMARY ................................................................................................................................. 85 APPENDIX A: CRAYFISH SAMPLING SUPPLEMENTARY MATERIAL .................... 87 APPENDIX B: CRAYFISH CAPTURE SUPPLEMENTARY MATERIAL ....................... 89 APPENDIX C: FALLICAMBARUS HARPI SAMPLING SUPPLEMENTARY MATERIAL................................................................................................................................. 94 APPENDIX D: PROCAMBARUS REIMERI SAMPLING SUPPLEMENTARY MATERIAL............................................................................................................................... 120 v CHAPTER 1: GENERAL INTRODUCTION The conservation of rare species is critical for the continuation of ecosystem function. Species considered rare can have a larger role in ecosystems than other more common species (e.g. keystone species; Power et al. 1996). Rare species contribute to ecosystem function by influencing pathways of energy and material flows (Hooper et al. 2005), resisting invasion (Lyons and Schwartz 2001), and delivering more unusual and important functions than their abundance would suggest (Mouillot et al. 2013). Conservation of rare species also adds to the biodiversity of an ecosystem, which in turn maintains the health of the ecosystem (Lyons et al. 2005). Unfortunately, the very nature of rare species (i.e., low abundance, narrow endemism) makes them difficult to study comprehensively. One such taxon in which rare species remain understudied are North American crayfishes (Taylor et al. 2007). Approximately two-thirds of the 500+ species of crayfish in the world occur in North America (Taylor et al. 2007). Within North America, the majority (99%) of species are assigned to the family Cambaridae (Taylor et al. 2007), which reaches its highest diversity in the southeastern United States. Increases in species diversity lead to an increase in ecosystem function across many taxa (see review by Hooper et al. 2005), and in particular, the diversity of crayfishes observed in North America results in species’ playing multiple roles in ecosystems. Throughout their range, crayfishes are vital to ecosystem function (Momot 1995). Crayfishes act as ecosystem engineers by consuming detritus (Usio and Townsend, 2002), creating terrestrial habitat (Carpenter, 1953; Horwitz and Knott, 1991; Kingsbury and Coppola, 2000; Seigel, 1986; Welch et al., 2008), modifying sediment layers (Harvey et al., 2011; Statzner et al., 2000), and breaking down leaf litter in streams (Creed and Reed, 2004; Schofield et al., 2001). Crayfishes serve as an important prey item for sport fish (Clady, 1974; Lewis et al., 1 1961), rare herpetofauna (Penn, 1950; Peterson at al., 1989; Smith et al., 1948), and many other aquatic and terrestrial animal species. Crayfishes can also act as predators (Parkyn et al., 2001; Taylor and Soucek, 2010) by preying upon aquatic and terrestrial invertebrates, fish, and other crayfishes. However, as the importance and number of roles crayfishes inhabit become clearer, so do the nature and breadth of the threats they face. Approximately one-third of the world’s crayfish species are threatened with extinction (Richman et al. 2015). In the United States and Canada, 48% of all crayfishes are considered imperiled (Taylor et al. 2007). In fact, crayfishes in the United States trail only freshwater mussels and snails in their level of imperilment (Wilcove and Master 2005). The specific threats facing native species of crayfishes include modification of species’ habitats or ranges, over-utilization, disease, and limited distributions (Taylor et al. 2007). Animals that are rare or possess a restricted range are more sensitive to these cumulative stresses than more common, widespread fauna. Intensifying these threats is the lack of natural history data for many crayfish species, particularly North American primary burrowing crayfishes (Moore et al. 2013). It is hypothesized all crayfishes have the ability to construct refugia and access ground or atmospheric water for oxygen extraction by burrowing into the soil or substrate (Berrill and Chenoworth 1982; Hobbs 1981). Based on differences in natural history, Hobbs (1981) described three classes of burrowing crayfishes: tertiary, secondary, and primary burrowers. Tertiary burrowers dig shallow burrows only to escape frost, lay and brood eggs, or avoid desiccation. Secondary burrowers spend much of their lives in their burrows, which normally have a connection to an open, permanent water body; however they do move out into open water occasionally. In contrast, primary burrowing crayfishes spend their complete life cycle 2 underground. As primary burrowers only leave their burrows to forage and locate a burrow of the opposite sex for mating (Hobbs 1981), their burrows are rarely tied to permanent open water. Rather, primary burrowers use subsurface groundwater for moisture and oxygenation.

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