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.
South 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]
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]
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.
I 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.
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]
A new publication documenting the historic distributional records of amphibians and reptiles in South Dakota was published in the June 2017 issue of Herpetological Review. This publication is a series of 100 county records from South Dakota collected over the past several decades from 18 different natural history collections. Many of these specimens were part of the former South Dakota State University collection that is currently housed at the University of South Dakota (and will soon be transferred to the Biodiversity Collections at the University of Texas at Austin). Included in these records is the only specimen of a Mudpuppy from South Dakota, a species historically reported in lists of the amphibians of South Dakota (Over 1923; Over 1943), but until now, no specimens were known to exist. These records highlight the continued importance of natural history collections, and especially, collections housed at regional or small universities. These South Dakota records have been added to the Amphibians and Reptiles of South Dakota website and help fill gaps in the distributions of species across the state.
Davis DR, Farkas JK, Johannsen RE, Maltaverne GA. 2017. Historic amphibian and reptile county records from South Dakota, USA. Herpetological Review, 48:394–406. [PDF]
The Philippines possess a remarkable species diversity of amphibians and reptiles, much of which is endemic to this Southeast Asia island nation. Lizard diversity in the family Gekkonidae is no exception, with more than 80% of the country’s gecko species endemic to the archipelago, including the entire genus of False Geckos (Pseudogekko). This small radiation of diminutive, slender, arboreal forest species has been the focus of several recent phylogenetic and systematic studies that have highlighted the prevalence of undocumented species concentrated in several geographical regions within the archipelago. Newly available genetic data have led to the revision of two species complexes in the genus Pseudogekko, one of which is the focus of this study. We describe a new member of the Pseudogekko brevipes complex, which represents the first population from this species group discovered in the Luzon Faunal Region. Because of the species’ secretive nature, rarity, or restricted geographic range, it has gone undetected despite recent biodiversity surveys targeting the central and northern portions of the Bicol Peninsula. We evaluate both morphological and genetic data to support the recognition of the new species. All three members of the P. brevipes complex have allopatric distributions situated within three of the archipelago’s distinct faunal regions. The recognition of the new species increases the total number of taxa in the genus Pseudogekko to nine species.
Siler CD, Davis DR, Watters JL, Freitas ES, Griffith OW, Binaday JWB*, Lobos AHT*, Amarga AKS, Brown RM. 2017. The first record of the Pseudogekko brevipes Complex from the northern Philippines, with description of a new species from Luzon Island. Herpetologica, 73:162–175. [PDF]
I was recently awarded a Wildlife Diversity Small Grant from South Dakota Game, Fish and Parks to promote and develop additional resources for the newly launched website www.sdherps.org. These funds were awarded to me and partners at HerpMapper, Inc. to promote the use of this website, increase public awareness of this resource, and encourage user-submitted observations of amphibians and reptiles from across the state. An additional goal will be to travel to the University of Nebraska State Museum (UNSM) in Lincoln, NE to examine and verify species identifications of voucher specimens that were formerly part of the University of South Dakota Herpetological Collection. The collection at UNSM represents the largest collection of amphibians and reptiles from South Dakota and represents a large portion of the data used to map species distributions (see www.sdherps.org/about). I am particularly interested in examining similar species pairs (i.e., Plains Leopard Frog vs. Northern Leopard Frog, Plains Gartersnake vs. Common Gartersnake) and rare species (i.e., Common Watersnake, Dekay’s Brownsnake).
Grant Title: Creating online resources to engage South Dakota citizens in amphibians and reptile identification and conservation
A natural history note describing a new prey item of Snapping Turtles (Chelydra serpentina) was published in the March 2017 issue of Herpetological Review. My co-author, Doug Backlund, photographed an adult male Northern Shoveler (Anas clypeata) being attacked by an adult Snapping Turtle on Farm Island, Hughes County, South Dakota. This observation adds to the list of waterfowl that have been reported as prey of Snapping Turtles and provides an account of predation events that are infrequently observed. Descriptions of the natural history of species such as this are critical and add to our understand of species.
Davis DR, Backlund DC. 2017. Chelydra serpentina (Snapping Turtle). Diet. Herpetological Review, 48:174–175. [PDF]