Dr. Levi Heffelfinger

Director of the North Texas Research Program and an Assistant Professor at the Caesar Kleberg Wildlife Research Institute at Texas A&M University-Kingsville

​Dr. Levi Heffelfinger's M.S. degree from University of Nevada, Reno involved evaluating the spatial ecology and modeling demographics of mule deer amid arid environmental constraints on the Mojave National Preserve in southern California. Levi received a Ph.D. with the Caesar Kleberg Wildlife Research Institute at Texas A&M University-Kingsville and also served as the Boone & Crockett Fellow in Ungulate Research. His doctoral research focused on modeling the influence of spatio-temporal fluctuations in forage on mule deer movement and population performance and experimentally evaluating the influence of early life nutrition on ontogeny and reproductive output in white-tailed deer. His current research focuses on spatial and nutritional ecology to connect population metrics to landscape variability. Much of his work involves large mammal conservation issues throughout arid regions including the southwestern United States and the southern Great Plains. Levi enjoys camping, hiking, wildlife photography, fishing, and hunting.

Bailey Kleeberg

Research Associate & Admin Coordinator
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Bailey Kleeberg was born and raised in western Colorado where she grew up hunting, fishing, and hiking the Rockies. She received her bachelor's degree in Wildlife & Fisheries Sciences from Pennsylvania State University in 2020. She received her master's degree in 2024 from Oklahoma State University. Her master's research involved investigating population genetics and space use of black bear in a semi-arid system. She previously worked with black bear, white-tailed deer, waterfowl, raptors, cold-water fisheries, and conducted stream restoration in the Chesapeake Bay region. Bailey's research interests include population genetics, movement ecology, and spatial ecology. In her free time Bailey enjoys flyfishing, reading, and playing fetch with her cat, Finnley.

Current Students

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Calvin Ellis

PhD Student

Population Dynamics & Spatial Ecology of Mule Deer
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Calvin is pursuing his Ph.D. under Drs. Levi Heffelfinger and Michael Cherry at the Caesar Kleberg Wildlife Research Institute with Texas A&M University - Kingsville. Calvin received his masters degree from CKWRI in December 2023 and his bachelors degree from the University of Georgia in December 2020. His primary research interests include population ecology, movement ecology, nutritional ecology, and predator-prey dynamics. For his Ph.D. research, Calvin is evaluating the population performance and spatial ecology of mule deer in western Oklahoma. Additionally, he is comparing abundance estimation methods to identify the best methodology for mule deer in the southern Great Plains. Calvin is from Hoschton, Georgia and spends his free time enjoying the outdoors, barbequing, photographing wildlife, and mentoring new hunters.

Ashlyn Halseth-Ellis

PhD Student

CWD Epidemiology
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Ashlyn Halseth-Ellis is a current Ph.D. student studying transmission dynamics and diagnostics of Chronic Wasting Disease in a multi-host system. Specifically, her research focuses on developing an agent-based model to simulate the spread of CWD among white-tailed deer, mule deer, and elk from two CWD-positive regions—the Texas Panhandle and Trans-Pecos. Before coming to CKWRI, she obtained her MSc from Ohio State University in 2024 where she studied sarcoptic mange infestations among radio collared coyotes in Chicago, Illinois. Outside of research, Ashlyn is passionate about wildlife education and outreach as she worked as the social media specialist with the non-profit organization, Georgia Wildlife Federation, served as an ambassador for National Wildlife Federation's Artemis program, and has designed numerous educational materials for various organizations.

Miranda Hopper

PhD Student

Interactions Between Native & Exotic Ungulates
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Miranda is pursuing her PhD at the Caesar Kleberg Wildlife Research Institute with Texas A&M University – Kingsville. Miranda received her masters from CKWRI in July 2024 and her bachelors from the University of Georgia in May 2021. Her research interests include movement ecology, thermal ecology, and population ecology, especially in the context of environmental change. Under the direction of Dr. Levi Heffelfinger and Dr. Michael Cherry, Miranda’s PhD work will focus on wildlife community dynamics, and specifically competition among native and exotic ungulates, in the Texas Hill Country. Miranda is originally from Covington, Georgia, and in her free time, she enjoys reading, playing piano, baking, and playing with her dog, Maggie.

Katie Pennartz

PhD Student

Current and Future Distributions of Wildlife Throughout the Southwest

Katie is a native Texan who obtained her bachelor's in Plant Science from the University of Texas and her Master's in Range and Wildlife Science from Texas A&M University Kingsville. Her thesis research focused on shrub encroachment in South Texas and ecological niche modeling. The majority of her work experience was gained as a botanist with the Assessment, Inventory, and Monitoring program run by the Bureau of Land Management and the National Ecological Observation Network. Through these positions Katie got the chance to explore the Southwest and fell in love with high desert ecosystems. She is excited to be returning to TAMU-K as a PhD student with research focused on the distribution of mammal and herptile communities in National Parks located on the Colorado Plateau. This research will be necessary for predicting species responses under changing conditions and aligns with her interests in community ecology and distribution modeling. In her free time Katie enjoys reading fantasy books, trail running, and building legos with her nieces and nephews.

Celine Rickels

MS Student

Pronghorn Population Dynamics
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Celine was born and raised in Iowa where she developed a passion for the outdoors through horse riding, camping, riding ATVs, and hunting. This love of nature led her to pursue a Bachelor of Science degree in Animal Ecology at Iowa State University. After graduating, she traveled to various states to work as a wildlife technician for universities and state agencies. She gained the incredible opportunity to work with a variety of animals including moose, elk, pronghorn, bighorn sheep, mule deer, grizzly bears, mountain lions, wolves, and greater sage-grouse. In January 2024, Celine joined Caesar Kleberg Wildlife Research Institute as a master’s student where her research focuses on pronghorn population dynamics in the Southern Great Plains of Oklahoma.

Austin Ibarra

MS Student

Cervid Species Interactions and Reproductive Ecology
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Austin is a current M.S student from Steamboat Springs, Colorado. His youth was spent hiking, snowmobiling, and camping in the mountains of Northwest Colorado where he developed his passion for wildlife and the outdoors. He received his bachelor's degree in Natural Resources Management from Texas Tech University in 2024. During his undergrad he had the opportunity to work in Texas, Colorado, New Mexico and Oklahoma. This work covered a range of species including mule deer, pronghorn, white-tailed deer, and white-winged dove. Austin’s masters work focuses on species interactions of elk, mule deer, and white-tailed deer in the Texas panhandle.