New Position: Associate Research Scientist at UTRGV

Last week I started in a new position as an Associate Research Scientist at the University of Texas Rio Grande Valley. Here, I am working to better understand factors associated with the distribution of the state-threatened Black-spotted Newt (Notophthalmus meridionalis), sirens, and Rio Grande Cooters (Pseudemys gorzugi) in south Texas. I’m excited to get settled into this position and help increase our understanding of these unique species in the Rio Grande Valley.

When not doing fieldwork, I will be based out of the newly acquired Port Isabel Research Station in Port Isabel, TX.

As part of this position, please note my updated contact information:

Address: 100 Marine Lab Drive, South Padre Island, TX 78597
Email: drew.davis (at)


Mud Turtle Research: 2018

I recently returned to Washington, DC 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). Working with these turtles continuously leaves us asking more questions about their ecology than we are able to answer. We trapped a total of 201 unique Yellow Mud Turtles at five permanent earthen tanks and a few more ephemeral sites that hold water for only a few days after rains. The newest earthen tank, #2, produced no turtles (compared to only a single turtle trapped last year), but numerous turtles were found in all other permanent sites. By the end of our trapping efforts, we were recapturing a high percentage (75–80%) of turtles trapped the preceding days. However, a large rain event (1.3″) at 96 Tank likely resulted in a low recapture percentage (25%), likely due to numerous turtles not seen in over a decade (despite annual trapping efforts at this site) moving to the site from terrestrial burrows.

96 Tank after heavy rains (notice the high turbidity)

Kimball Draw

Adult female Yellow Mud Turtle (Kinosternon flavescens) with an advanced stage of shell disease


New publication: 54 new county records for South Dakota

A new publication documenting 54 new distributional records of 17 species of amphibians and reptiles in South Dakota, all collected during 2017, was published in the June 2018 issue of Herpetological Review. Included are numerous records of Boreal Chorus Frogs (n=8) and Painted Turtles (n=8). Also included are six new records of Northern Leopard Frogs, a species for which there is now vouchered material from every county in the state. These specimens are verifiable records of species presence and serve as vouchered material from a historically under-sampled state. All 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. 2018. New county records of amphibians and reptiles from South Dakota, USA from 2017. Herpetological Review 49:288–295. [PDF]


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]


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: 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]


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]


New publication: historic distributional records for South Dakota

A new publication documenting the historic distributional records of amphibians and reptiles in South Dakota was published in the June 2017 issue of Herpetological ReviewThis 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]


New publication: new species of Pseudogekko from the Bicol Peninsula, Philippines

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]


Funding awarded by SD Game, Fish and Parks to support website

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 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 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