Unit's name.

Meet the Researchers

Principal Investigators, Co-Investigators, Student Researchers

Principal Investigators


Dave Garshelis, Ph.D.

Bear Project Leader, Minnesota Department of Natural Resources; Adjunct Associate Professor, Department of Fisheries, Wildlife and Conservation Biology

Dave Garshelis' research during the past decade involves bears and sea otters, although his interests are not limited to these species. He is broadly interested in developing methods for monitoring population status (size, trends, limiting factors), implementing such monitoring programs, and utilizing results to develop management or conservation strategies. As a research biologist for the Minnesota Department of Natural Resources, Dave has been able to directly apply the population monitoring approaches for black bears that were developed through his research, and then utilize the results to effect appropriate management strategies.

Paul A. Iaizzo, PhD

Professor of Surgery, Integrative Biology and Physiology and the Carlson School of Managment, University of Minnesota, Associate Director, Institute of Engineering in Medicine; Distinguished University Teaching Professor; Medtronic Professor of Visible Heart Research; Director for Education; Lillehei Heart Institute, Director, Malignant Hyperthermia Muscle Biopsy Center

Paul Iaizzo's primary research focus is translational systems physiology, and his research group has developed a unique isolated working large mammalian heart model. The Visible Heart Laboratory is well known for its novel imaging techniques of cardiac anatomy and physiology, and is an ideal place to perform translational systems physiology research. Other research interests include cardiac pacing, skeletal muscle pathophysiology, thermoregulation, black bear hibernation, wound healing, and spine biomechanics. Paul has authored more than 260 original articles, edited 7 books, and holds multiple patents (both U.S. and European) related to cardiac anatomy, physiology, and devices.

Tim Laske, PhD

Vice President of Research and Business Development, Medtronic Cardiac Ablation Solutions; Adjunct Professor, Department of Surgery, University of Minnesota

Tim Laske currently has responsibilities in Research, Intellectual Property and Business Development for cardiac ablation products and systems at Medtronic. His previous roles during his 28 years at Medtronic included Vice President of Product Development for AF Solutions, Senior Director of Heart Valve Product Development, Senior Program Director for Transcatheter Heart Valves, Technology Director for Therapy Delivery in Cardiac Rhythm Disease Management, and technology management and design engineering positions in Tachyarrhythmia Lead Development. Prior to Medtronic, Tim worked as a Design Engineer at Ford Motor Company in Crash Safety and Advanced Vehicle Systems Engineering.

Andrew Tri, PhD CWB®, CWT®

Research Wildlife Biologist, Minnesota Department of Natural Resources, Adjunct Assistant Professor, Texas A & M University–Kingsville

Andrew Tri’s research emphasis has been on the ecology and management of game species in the US and Mexico (American black bear, upland game birds, and ungulates). He is interested in population dynamics, spatial ecology, and incorporating the quantitative methods into an adaptive management framework.

Mark Ditmer

Postdoctoral Researcher, Boise State University

Mark completed his Ph.D at the University of Minnesota in 2014 studying how American black bear movements, diet and physiology are influenced by habitat fragmentation in a largely agricultural region. His current research, for the Minnesota Zoo, is studying how moose movement and habitat selection are influenced by wolves. Additionally, he is continuing his previous research utilizing cardiac biologgers, inserted in bears subcutaneously in conjunction with GPS-collars, to better understand causes of stress in wildlife (e.g., road crossings, drones)


Student Researchers

Spencer Rettler M.S.

Spencer is a PhD student in Fish Wildlife and Conservation Biology. His research is focused on how American black bears (Ursus americanus) respond to short-term and long-term changes in natural food availability (i.e., fruits and nuts). Located in northcentral Minnesota, the bear population in the study area has been monitored by the Minnesota Department of Natural Resources (DNR) since the early 1980s. Because of this collaboration with the DNR, there is access to an exceptional database on this bear population. His Master's research demonstrated that natural food availability had substantially declined since the 1980s. For his PhD, he will explore the bears' response to this declining food. More specifically, seeking to answer these questions: Do bears use the landscape differently than they did in the 1980s? Do bears compensate for the lack of natural foods by consuming more human foods? How do different foraging techniques affect a bear's physiology? Through this research, he hopes improve our understanding of how trends in food availability impact a hunted bear population.


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