HomeAboutThe InvadersMembershipMeetings/MinutesNewsContact

Invasive Species Working Group Board

Contact us at TWS.ISWG@gmail.com


Jennifer Ketterlin

Jenny Ketterlin is an invasive species biologist with a federal agency where she is responsible for coordinating regional invasive species management activities in California, Nevada, and part of Oregon. Prior to this position, she worked on invasive species issues in Florida for over 17 years with the National Park Service, University of Florida, the Miami-Dade County Environmentally Endangered Lands Program, and the Florida Fish and Wildlife Conservation Commission. Her experience is in wildlife and habitat management with a wide variety of species and ecosystems, especially nonnative plants and animals. Some significant projects she has been a part of include restoration of Brazilian pepper-infested tree islands in the Everglades to native trees and shrubs, control and assessment of Argentine black and white tegus in south and central Florida and the development and implementation of the 2013 and 2016 Python ChallengesTM. Jenny serves with TWS in her personal capacity, not as a representative of her agency. 

Chair Elect

Jane Anderson

Caesar Kleberg Wildlife Research Institute

Dr. Jane Anderson is an Assistant Professor of Research in the Caesar Kleberg Wildlife Research Institute at Texas A&M University – Kingsville. She has previously held positions in the public, private, and non-profit environmental sectors, and she is particularly interested in coupled human-natural systems. Jane’s research is focused on the ecology and management of charismatic invasive species. She previously spent six years studying non-native monkey populations in Florida, with a focus on the invasive rhesus macaque population in central Florida. Currently she is leading a study funded by the USDA National Wildlife Research Center of the ecology and management of invasive rose-ringed parakeets on the island of Kaua’i.

Past Chair

Steve Johnson

University of Florida

Dr. Steve A. Johnson is an Associate Professor of Wildlife Ecology at the University of Florida in Gainesville. He holds a Ph.D. from the University of Florida and B.S. and M.S. degrees from the University of Central Florida. Dr. Johnson’s area of expertise is natural history and conservation of amphibians and reptiles. Prior to his employment at UF, he worked as a Research Wildlife Biologist for the US Geological Survey’s Amphibian Research and Monitoring Initiative. He, his students and his collaborators conduct research on invasive species—their studies have focused on Cuban treefrogs, cane toads, coqui frogs, rhesus macaques, tegu lizards, and others. Dr. Johnson’s outreach program emphasizes invasive species education and he has authored numerous “fact sheets” on invasive vertebrates in Florida (see some examples here). He incorporates case studies of invasive animals into his courses at UF and he teaches a course specifically on invasion ecology of amphibians and reptiles that has a global focus. In 2018 he received the Paul Moler Herpetological Conservation Award from the Florida Chapter of TWS for his career-long commitment to conservation of amphibians and reptiles. He has been a member of TWS for over 15 years. Steve is a native Floridian, enjoys being outdoors, and is a beer snob.


Tessie Offner

Tessie Offner has had 10 years experience working with invasive wildlife and plants in Florida, including six years as part of the Invasive Species Program for Florida Fish and Wildlife. She obtained her masters in Wildlife Ecology and Conservation from the University of Florida where her primary research was focused on Argentine black and white tegus.

At-Large Board Members

Rob Gosnell, CWB®

Wildlife Services

Mr. Rob Gosnell is the State Director for Wildlife Services (WS), New Mexico, where he assumed the duties on 1 Oct 2019. He previously served as the State Director for Guam & the Western Pacific Theatre, a program in USDA, Animal Plant and Health Inspection Service. In this position, Goose was responsible for overall planning, coordinating, and direction of WS operational programs in his area of operations. This includes oversight of work on Guam, the CNMI, and Diego Garcia and soon to be Japan and Okinawa with a budget of $ 6± million dollars. Before assuming the role of State Director, Goose was the State Director for the Louisiana Department of Wildlife & Fisheries (LDWF) where his directorate included, Large Carnivore, Farm Bill/NRCS Coordination, Private Lands, Hunter & Aquatic Education, Upland Game Birds, Turkey, and Research Programs. Prior to service for the State of Louisiana, he was Complex Biologist for the Southwest Louisiana National Wildlife Refuge Complex system, US Fish and Wildlife Service (USFWS). As the Complex Biologist, Goose was instrumental in authoring the Habitat Management Plans for each refuge, Research, Pesticide/Herbicide oversight for the SE United States, and moist soil management for migratory waterfowl and other species of concern. Goose also was the Operations Chief of the Wildlife Branch at Ft Stewart, Ga. for the Army. His biologists (14) and technicians (29) covered a 284,000 acre installation dealing with fish and game management, habitat recovery, TES management, Outreach and Education and the mission of military training on the landscape.

Goose is a lifelong wildlife biologist and outdoor enthusiast. He hails from coastal southwest Louisiana. After a six year stint in the early 70’s as a USAF PJ “pararescueman” he was honorably discharged and pursued his career in wildlife. Goose earned a BS in Wildlife Conservation and Management from Southwest Missouri State University and a Masters in Wildlife Sciences from Texas A & M University. Goose has recently been awarded a Certificate of Public Leadership from the Brookings Institute in Washington DC.

Susan Jewell, CWB®

Susan (Su) is a wildlife biologist for a Federal agency where she is an invasive species biologist. Previously, she spent 12 years working in the Everglades, first for the National Audubon Society on wading birds, then in Everglades National Park on alligators, wading birds, and fisheries; and also in A.R.M. Loxahatchee National Wildlife Refuge as the senior biologist. She subsequently spent 11 years in working on endangered species for a Federal agency. She is also an accomplished author of books and articles on environmental subjects. Su serves with TWS in her personal capacity, not as a representative of her agency.

MJ Mazurek

Mary Jo (MJ) Mazurek is a wildlife biologist currently employed as the Brown Treesnake (BTS) Program Coordinator for the Pacific Islands Fish and Wildlife Office in Honolulu, Hawaii.  Previously MJ worked for five years in Guam on BTS management for USGS and the Department of the Navy and for two years in Hawaii developing invasive vertebrate eradication plans for Island Conservation.  Prior to her time in the Pacific, MJ worked for a variety of federal agencies and private firms in northern California on wildlife management projects related to wildlife habitat selections in managed forests for Spotted Owls, Marbled Murrelets, bats, amphibians, and small mammals. MJ received a B.S. in Biology at the University of Central Florida and a M.S. in Natural Resources Management from Humboldt State University.    

Pete Caldwell

Pete Caldwell is a Biosecurity Consultant and Project Manager for a leading environmental planning and design firm in New Zealand. Previously he has worked for the New Zealand Department of Conservation; the Invasive Species Branch of Department of Primary Industries, Parks, Water and Environment in Tasmania, Australia, among others. A lot of his work with invasive species has focused on plants, but his passion is management of invasive animals, especially mammals. Pete has expertise with management of mustelids, pigs, and rabbits. He recently helped design and implement a program focused on eradicating invasive wallabies at the invasion front in New Zealand’s South Island.

Ben Wishnek, AWB®

Ben Wishnek is currently an invasive species project manager in southern Alaska.  He has a BS in Wildlife from Humboldt State University and a MS in Environmental Sciences from Oregon State University.  He served on the board of the TWS Wildlife and Habitat Restoration Working Group from 2012-2018 and was on the scholarship committee for the Idaho Chapter of The Wildlife Society since 2018-2020. Much of his professional experience has centered around wetlands and riparian areas with invasive species, primarily plants, being a focus area.  He looks forward to the opportunity to bring his perspectives to the Working Group.

Kodiak Hengstebeck

Kodiak Hengstebeck is a PhD student in the School of Natural Resources and Environment at the University of Florida, where he works in the Florida invasion ecology lab. His research interests lie within the fields of invasion ecology and evolutionary ecology, with particular focus on reptiles and amphibians. Currently, his research centers around the evolutionary and ecological impacts of snake invasions, focusing specifically on adaptive morphological changes and zoogeochemical impacts of invasive Burmese pythons. He also obtained his M.S. from the University of Florida, during which he researched Burmese pythons in southwestern Florida and their interactions with gopher tortoises and gopher tortoise burrows. When he’s not working, Kodiak enjoys kayaking, scuba diving, or taking his dog, Gus, hiking on some of the many trails around Gainesville.