New publication: South Dakota Conservation Digest article

This spring I was asked to write an article about my efforts in mapping amphibians and reptiles across South Dakota. Since 2012, I have collected voucher specimens and photographs of amphibians and reptiles that I encountered at research study sites, during camping trips, driving down county roads, and pretty much every other time I was outdoors when it wasn’t winter. These records represent a significant increase (>60%) in the number of verifiable records from the state and provide much needed voucher material for current and future studies. While I continue to collect voucher specimens from the state, citizen scientists are also contributing to what is known about distributions of species in the state. In 2017, I launched a new website, Amphibians and Reptiles of South Dakota (, and have encouraged citizen scientists to submit their own observations of amphibians and reptiles they encounter while outdoors. In 2017, over 900 records were added to, all of which help to better map species distributions in the state. Hopefully even more records are submitted to the website in 2018.

Davis DR. 2018. Mapping amphibians and reptiles in South Dakota. South Dakota Conservation Digest 85:34–37. [PDF]


Funding awarded to survey for endangered Lined Snakes in South Dakota

Today I received notice that I was awarded a Wildlife Diversity Small Grant from South Dakota Game, Fish and Parks to survey for the state-endangered Lined Snake (Tropidoclonion lineatum)Within South Dakota, the Lined Snake was thought to occur only in habitats along the Big Sioux River watershed, until I collected a specimen was collected near the James River in Hutchinson County in October 2017. This recently collected snake represents the most northwestern occurrence for this species, provides evidence that populations of Lined Snakes may exist outside of the Big Sioux River watershed, and suggests that the distribution of Lined Snakes in South Dakota may be greater than expected. To better understand the distribution and occurrence of Lined Snakes in southeastern South Dakota, I proposed to conduct a series of targeted surveys for Lined Snakes along the lower James River valley.

Grant Title: Surveys for the state-endangered Lined Snake (Tropidoclonion lineatum) along the lower James River Valley

Lined Snake distribution map from

New publication: Eastern Hog-nosed Snake distribution note

DRD3404.jpegI recently discovered a preserved Eastern Hog-nosed Snake (Heterodon platirhinos) from Brule County, South Dakota (pictured) that represents an important distributional record in the state. Heterodon platirhinos was historically known from southeastern South Dakota in Union and Clay counties. This specimen, from Chamberlain, is roughly 300 km up the Missouri River from previously known localities in Clay County, South Dakota. This historic specimen, combined with recent observations of H. platirhinos from western South Dakota (see suggest this species may be present in additional localities across the state and further surveys for this state-threatened species should be a conservation priority.

Davis DR. 2018. Geographic distribution: USA, South Dakota, Brule Co.: Heterodon platirhinos (Eastern Hog-nosed Snake). Herpetological Review 49:76. [PDF]


New publication: C. E. Miller Ranch checklist

We report the occurrence of 50 species of amphibians and reptiles recently collected on C. E. Miller Ranch and the Sierra Vieja in the Chihuahuan Desert of Texas, USA and describe their perceived distribution and abundance across various habitat associations of the region. Our recent surveys follow intense, historic sampling of amphibians and reptiles from this region in 1948. Of the 50 species detected in recent surveys, six were not collected in 1948 and an additional three species documented in 1948 have yet to be detected in a 14-year period of recent surveys. Combining data from both historic and recent surveys, a total of 53 species of amphibians and reptiles are known from the ranch (11 amphibians, 42 reptiles). Land stewardship and conservation practices have likely contributed to the persistence of the majority of these species through time. Additionally, we discuss the status of amphibians and reptiles not collected during recent surveys and comment on potential species that have not yet been detected.

Davis DR, LaDuc TJ. 2018. Amphibians and reptiles of C. E. Miller Ranch and the Sierra Vieja Range, Chihuahuan Desert, Texas, USA. ZooKeys 735:97–130[PDF] [Corrigenda]


Specimens deposited at Biodiversity Collections

I recently deposited approximately 3600 amphibian and reptile specimens (DRD Field Series) and 3000 tissue samples at the Biodiversity Collections, University of Texas at Austin. These specimens are primarily collected from South Dakota and northeastern Nebraska, but also represent recent collecting trips to Michigan, Wisconsin, and Iowa. Further, this collection includes former South Dakota State University, W. H. Over Museum of Natural History, University of Sioux Falls, Augustana University, and Wayne State College specimens. Travis LaDuc, Curator of Herpetology at the Biodiversity Collections, recently traveled up to Vermillion to pick up these specimens from me at the University of South Dakota. Two days of driving later, they have all arrived safely in Austin, Texas. Specimens will be cataloged over the coming months and soon be available for researchers to loan out for studies.


New publication: Lake Oahe, South Dakota distributional records

Apalone_spinifera_DRD-4106South Dakota amphibian and reptile distributional records are lacking, especially in the north-central counties in the state. To date, there have been few surveys of amphibians and reptiles from along Lake Oahe, a large reservoir on the Missouri River that was created in 1958 following construction of Oahe Dam. We conducted fieldwork on Lake Oahe in South Dakota in June 2017 and collected 13 new county records of six species of amphibians and reptiles: Woodhouse’s Toad (Anaxyrus woodhousii), Boreal Chorus Frog (Pseudacris maculata), Smooth Softshell (Apalone mutica), Spiny Softshell (Apalone spinifera), Painted Turtle (Chrysemys picta), and Plains Gartersnake (Thamnophis radix)Prior to these records, no vouchered specimens existed from these areas for these species and only anecdotal evidence or unverifiable reports of species occurrence existed. These vouchered specimens are important as they provide the first verifiable records of species occurrence in an area that is under-surveyed and depauperate of records.

Austin SD, Kerby JL, Davis DR. 2017. Distributional records of amphibians and reptiles from Lake Oahe, South Dakota, USA. Herpetological Review 48:817–820. [PDF]


New publication: urbanization and stress in threatened salamanders

Jollyville Plateau Salamander. Photo by Nathan Bendik.

Urbanization has the potential to induce major changes in freshwater systems. Expected increases in human populations will likely amplify these changes and lead to the overall degradation of habitat quality within these systems. Such habitat alterations may function as stressors that can affect glucocorticoid stress hormones in freshwater vertebrates. Examining changes in physiological stress may provide early warning indicators of environmental threats and provide insights into the sub-lethal effects of habitat degradation. The threatened, obligate aquatic, Jollyville Plateau salamander (Eurycea tonkawae) is found in urbanized and rural catchments within central Texas and has experienced population declines in heavily urbanized areas. We tested the prediction that salamanders from urbanized sites would have different levels of baseline corticosterone (CORT) and muted or no stress responsiveness (to an external stressor, agitation) compared to salamanders from rural sites. We collected water-borne hormones to measure baseline CORT release rates (n = 3 years) and stress responsiveness (n = 2 years) in salamanders inhabiting urbanized and rural sites. We also measured “background” CORT from stream water alone at each visit. For the first two years we found that baseline CORT was higher in urbanized sites but not in the third year. Across years and populations, salamanders showed stress responsiveness, suggesting that, even if physiological stress is higher in urbanized areas, it has not resulted in the impairment of the hypothalamic–pituitary–interrenal axis. Background CORT was higher in urban than in rural streams and was positively correlated with mean baseline CORT of salamanders across populations and years. Our results contribute to the goal of finding early warning indicators of environmental threats by demonstrating a relationship between urbanization and the physiological status of E. tonkawae, using a rapid, non-invasive measure of stress.

Gabor CR, Davis DR, Kim DS, Zabierek KC, Bendik NF. 2018. Urbanization is associated with elevated corticosterone in Jollyville Plateau Salamanders. Ecological Indicators 85:229–235. [PDF]


Mud Turtle Research: 2017

I’ve recently returned to South Dakota from my annual trip out to the Chihuahuan Desert of west Texas where I have been collaborating on multiple research projects involving the Yellow Mud Turtle (Kinosternon flavescens). I have been marking and studying turtles in both ephemeral and permanent cattle ponds at this study site for 11 years. In addition to taking morphometric measurements of individuals, we have tracked movement, used iButtons to measure temperatures (as a proxy for when turtles are moving to and from these ponds), and monitored an undescribed shell disease. This trip (6 days of mark-recapture) resulted in over 200 unique turtles collected, with numerous young (1–2 year-old), unmarked individuals.



JMIH 2017: Austin, TX

JMIH2017_logo_smallI recently returned from the Joint Meeting of Ichthyologists and Herpetologists (JMIH) in Austin, TX where I presented both an oral and a poster presentation. My oral presentation, “Physiological Stress and Pathogen Infection in Larval Salamanders from Agricultural Wetlands”, was on one of my dissertation chapters and my poster presentation, “Morphological Variation between two widely distributed populations of Plethodon albagula (Caudata: Plethodontidae)”, was a continuation of work that I began as an undergraduate at the University of Texas at Austin. To my surprise, the poster presentation won the Victor Hutchinson Award (Morphology and Physiology) from the Society for the Study of Amphibians and Reptiles! I had a great time visiting with current and future colleagues. Many thanks to the local hosts and organizing societies for a successful, fun, and engaging meeting.



New publications: two snake natural history notes

Two natural history notes were published in the June 2017 issue of Herpetological Review. One note reports a new prey item and a new maximum prey/predator mass ratio for the Chihuahuan Nightsnake (Hypsiglena jani) and is co-authored with Travis J. LaDuc. Previously, the maximum prey/predator mass ratio known for Hypsiglena was 0.54 reported by Lacey et al. (1996), but our observation increases the maximum to 0.58. The two prey items that were consumed by this individual were two Little Striped Whiptails (Aspidoscelis inornata). Additionally, this observation adds to the list of prey species known to be consumed by Hypsiglena as only two other species of Aspidoscelis have been reported in the diet of Hypsiglena

Davis DR, LaDuc TJ. 2017. Hypsiglena jani (Chihuahuan Nightsnake). Diet and Prey Size. Herpetological Review 48:450–451. [PDF]

The second is a report of predation of a juvenile North American Racer (Coluber constrictor) by a theridiid spider from Vermillion, South Dakota. One of my co-authors, Mark Dahlhoff, photographed and observed this incident over several days. While the exact circumstances leading to the snake’s entrapment in the spider web are unclear, it may be that the juvenile snake was attempting to either capture and consume the spider or other insects in the web. While spiders are known as prey items of Coluber constrictor, this is the first report of spider predation on this species of snake and may suggest bidirectional predator-prey interactions between these two species.

Davis DR, Farkas JK, Kerby JL, Dahlhoff MW. 2017. Coluber constrictor (North American Racer). Predation. Herpetological Review 48:446–447. [PDF]