Lab Members

Doctoral Students

Hannes Schraft

I received a BSc in Biology at the University of Puerto Rico where I was involved in research on the performance of trilled bird songs. Since then my interests have shifted slightly to the behavior and sensory ecology of reptiles. My dissertation will investigate the resolution and sensitivity of rattlesnake pit organs, and the extent to which rattlesnakes can use leaked thermal information from their prey to make foraging decisions. Specifically, I want to determine whether rattlesnakes make decisions regarding striking prey or ambush site selection based on their prey’s thermal signatures.   Email:

Whitford, Malachi

Malachi Whitford

Broadly, I am interested in how the behaviors of both predator and prey influence the outcome of predatory interactions. My current research uses in situ  facilitated interactions between rattlesnakes and kangaroo rats, coupled with high-speed videography techniques, to discern whether behaviors expressed during an interaction and/or the morphology of the participants predict the eventual outcome of the interaction.Email:

Grace Freymiller

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I am interested in the mechanistic and functional underpinnings of the often-complex behaviors expressed during predator-prey interactions (e.g. evasion maneuvers, antipredator displays). My research focuses on the evasion maneuvers of free-ranging kangaroo rats (Dipodomys spp.) when escaping rattlesnakes (Crotalus spp.), a sit-and-wait ambush predator. I am currently exploring how their evasion performance is altered by various ecological and morphological factors, including a multi-species comparison of jump performance. Additionally, I hope to elucidate the specific biomechanical advantages that a bipedal morphology provides these unique rodents during escape maneuvers. Email:

Dylan Maag

I received my B.S. in Fisheries and Wildlife with a focus on Conservation Biology from the University of Nebraska-Lincoln and my M.S. in Biology at Missouri State University.  During my Master’s, my research was focused on the spatial ecology and habitat selection of the pygmy rattlesnake, Sistrurus miliarius.  Currently, my research interests are in the ecological and evolutionary aspects of predator/prey systems revolving around snakes, both as predators and prey.  However, I still hold interests in in other areas of herpetology including, spatial ecology, foraging ecology, and the evolution of sensing organs.  Email:

Masters Students

Kelly Robinson

I received my B.S. in Environmental Science with a focus in Biology from the University of Iowa. I have general interests in behavior, predator-prey interactions and conservation of herpetofauna. My current research is being conducted on the variation in venom resistance among California ground squirrels (Otospermophilus beecheyi) and woodrats (Neotoma spp.). I will be exploring the variation and potential constraints of their resistance levels to two species of local rattlesnakes; red diamond rattlesnake (Crotalus ruber) and southern Pacific rattlesnake (C. helleri).


Roman Nava

My main interests are animal behavior and conservation, and here I am interested in how species change their behaviors as a result of natural and anthropogenic fragmentation, and seeing if there is any convergence (or difference!) in how species respond to fragmentation across fragments created by urbanization or islandization . I look at morphological changes coupled with personality assays, combining two sets of data to draw insights from. My current project tests these ideas on a handful of squamates at a few sites around San Diego County and Coronado Sur of Baja California, Mexico. As urbanization rapidly increases, it is important to know if species are responding to fragmentation caused by humans in a similar way to fragmentation caused by natural forces over thousands of years. 

Jordyn Mulder

I received my B.S. in Wildlife Biology with an emphasis in management and conservation at Humboldt State University in 2013. Since then, I have pursued my passion for herpetofauna.  My main topics of interest are animal behavior, conservation, and human and wildlife interaction. My current research is in San Diego studying local lizard populations and using skeletochronology to determine morphological changes over time due to isolation and climate change. Email:


Craig Fischer

I have long been interested in myriad aspects of ecology, using my bachelor's in Biological Sciences from Marquette University and bio tech positions in public lands to ask pointed questions about effects of climate change, habitat alteration, and recreation on ecology of public lands. Four years working in the Colorado Desert have given me ample opportunity to develop questions regarding the ecology of this remarkable region. My research focuses on how natural and anthropogenic landscape factors may affect genetic diversity of flat-tailed horned lizards (Phrynosoma mcalli) within an off-road focused recreation environment. Email:


Nathaniel Redetzke

I am working as a wildlife officer at Camp Pendleton while obtaining my MS degree in the Clark lab.  Part of my duties involve translocating venomous snakes that show up near houses or active training operations. For my thesis work, I am studying how individual variation in snake temperament mediates their response to translocation. This involves using a series of behavioral assays to characterize snake temperatment, and then using radio telemetry to also quantify the spatial ecology of translocated and non-translocated snakes. Email: 

Nathan Smith


I'm a lifelong Herpetologist. I graduated Cal State San Marcos in Fall of 2015 with a BS in Biology and Ecology concentration. I've been seriously pursuing and recording reptiles and amphibians in the San Diego region since 2007 with over 2,000 records in the database. I am currently a field tech with USGS at the Western Ecological Research Station, San Diego working on projects focused on endangered and threatened species. I am trying to expand my depth of knowledge about the species present in San Diego beyond the herptofauna which I have dedicated most of my time to studying. Scorpions are one of my other primary interests. Email:

Clark Lab Alumni

Matthew Barbour, MS 2012, Investigating the function of California ground squirrel (Otospermophilus beecheyi) displays towards northern Pacific rattlesnakes (Crotalus oreganus)  

Frank Santana, MS 2013, Mountain yellow legged frog (Rana muscosa) conservation: multiple approaches

Shannon Hoss, PhD 2013, Maternal attendance of young in cottonmouths (Agkistrodon piscivorus): Adaptive value and hormonal mechanisms.s

Laura Kabes, MS 2014, The use of chemical cues by granite night lizards (Xantusia henshawi) to evaluate potential predation risk

Bree Putman, PhD 2015, The function and ontogeny of antipredator responses: the influence of snakes on ground squirrel behavior and physiology 

Tara Luckau, MS 2015, Comparative conservation genetics of two sympatric lizard species across multiple landscapes in San Diego County

JP Montagne, MS 2015, The effect of personality on movement and survival following translocation of California ground squirrels (Otospermophilus beecheyi)

Kelly Lion, MS 2016, A comparative study of genetic patterns in two closely related and sympatric Peromyscus species

Stephen Rice, PhD 2017, Conservation genetic assessment of the Island Night Lizard, Xantusia riversiana, under contemporary and future environmental conditions

Last Updated:  March 2019