Conservation of Kirtland’s Snake – A Wet Prairie Species Specialist

Over the past century, human-induced pressures have increasingly threatened wildlife by contributing to population declines and extirpations. Between 16 percent and 33 percent of vertebrate species are threatened with extinction, with the proportion growing annually. Such declines have been triggered by anthropogenic stressors such as habitat loss, overharvesting and climate change. Kirtland’s snake (Clonophis kirtlandii; Figure 1) is a fossorial species inhabiting wet prairies, wet meadows, prairie fens and associated wetlands (Figure 2) throughout its range; its range is primarily restricted to Illinois, Indiana and Ohio with scattered populations in six additional states (Figure 3).

Due to the drainage and conversion of wetland habitats to support agriculture and urban developments, pristine Kirtland’s snake habitats are scarce across its range. Most of the specific habitat information for Kirtland’s snakes comes from urban settings such as parks, vacant lots and drainage ditches. A central feature of Kirtland’s snake habitat is abundant crayfish and small mammal burrows, where the snakes seek shelter throughout the year. When above ground, they often take refuge under cover objects or in tufts of grass.

Once thought to be a common species in the prairie peninsula of the midwestern USA, Kirtland’s snake is now listed as an imperiled species in eight of the nine states in which it occupies. Range-wide population declines have seemingly occurred due to habitat destruction and development pressures. In 2017, the U.S. Fish and Wildlife Service (USFWS) provided a 12-month evaluation of Kirtland’s snake for a proposed listing under the Endangered Species Act. The USFWS report addressed numerous stressors, including habitat loss and degradation, road mortality, management practices such as mowing or controlled burns, snake fungal disease, and climate change. Ultimately, the conclusion was made that the data currently available did not indicate stressors would result in population- or species-level impacts. Protection was denied to Kirtland’s snake due to signs of resiliency, citing the persistence of populations at seemingly high densities in degraded habitats across a large range. However, reliable estimates of Kirtland’s snake vital rates and other population-level variables are non-existent. Less than 50 percent of historical sites were found to support extant populations, with the status of Kirtland’s snake at most sites remaining unknown.

Prairie and wetland loss over the past century in Illinois has raised concerns over the status of the cryptic Kirtland’s snake. Within the state, the Kirtland’s snake primarily inhabits wet prairies but can also be found along the margins of streams, ponds, bogs and lakes. Populations have also been observed in several marginal habitats with high water tables such as drainage ditches, wooded areas, suburban lots and at the periphery of large lake impoundments. The soil in these areas tends to be mostly clay and littered with crayfish and small mammal burrows, which Kirtland’s snakes use as refugia. Statewide surveys for Kirtland’s snakes in Illinois in the 1990s resulted in the detection of only two populations from 33 sites, where evidence suggested 19 of the sites supported them. Further, 90 percent of Illinois’ wetland habitat has been drained, 99 percent of woodland savanna habitat has been lost, and less than 0.1 of native prairies remain in the state; therefore, extirpation due to habitat loss poses a significant threat. The substantial habitat loss warranted a state listing as a threatened species in Illinois, yet the true status of Kirtland’s snake remains uncertain.

Over the past five years, researchers at the Illinois Natural History Survey (Michael Dreslik, Andrew Kuhns, Tyler Stewart and Christopher Phillips) and National Great Rivers Research and Education Center (John Crawford) have been conducting studies for the conservation and management of Kirtland’s snakes in Illinois. During the course of our work, we have discovered a handful of previously unknown populations and generated a predictive map that identifies sites that have a high probability of harboring Kirtland’s snakes. Further, we found that under ideal weather conditions (moderate temperatures, low humidity and high cloud cover in May and June) only a few surveys are needed at a site to determine if Kirtland’s snakes are present. Based on this information, we have created a Microsoft Excel-based spreadsheet tool that researchers and land managers can use to determine if a particular day is appropriate to search for Kirtland’s snakes, which dramatically reduces wasted time and effort.

Nearly 60 percent of the Earth’s terrestrial habitat is under moderate to intense human pressure; thus, the ranges of many species have become restricted or fragmented due to anthropogenic disturbance. In many cases, local extirpations have coincided with habitat destruction and population isolation. As a result, historical records of species occurrences no longer correspond with contemporary distributions. Conservation decisions rely heavily on our ability to identify where populations are distributed on the landscape. Uncertainty about the true distribution of a species inhibits our ability to identify conservation needs. Furthermore, doubt over the occupancy of a habitat patch impairs our ability to provide meaningful and timely conservation actions. By employing our research findings and methodologies range‐wide, Kirtland’s snake distributions can be thoroughly assessed through targeted presence‐absence surveys. Repeated surveys over many years should determine how Kirtland’s snake populations are changing and inform future conservation decisions. In the wake of widespread population declines and extirpations, it is vital to establish wildlife monitoring programs to confirm population extent and identify critical habitats for conservation.

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Dr. John Crawford is a Terrestrial Wildlife Ecologist with the National Great Rivers Research and Education Center. A primary goal of his research is to conduct projects that answer important contemporary questions related to the conservation and management of lower vertebrates. He prefers to conduct research that bridges disciplines and combines current thinking and needs in multiple areas to approach and answer these questions. His primary research interests have been and continue to be on the effects of habitat alteration, habitat degradation, and global climate change on amphibian and reptile populations. He earned his B.S from the University of Illinois (Urbana-Champaign), his M.S. from Illinois State University, and his Ph.D. from the University of Missouri (Columbia).