The USA-NPN's National Coordinating Office (NCO) guides the development of the Network, facilitates communication between scientists, land managers, policy-makers, and the public who are interested in assessing the effects of global change on natural ecological systems. Staff members are employees of The University of Arizona.

Theresa Crimmins staff photo

Theresa Crimmins 
(520) 621-8523
Short CV

Theresa Crimmins is the Director for the USA National Phenology Network and has been a part of the organization since 2007. Hailing from Ohio and Michigan, she received a B.S. and M.A at Western Michigan University and a Ph.D. from the University of Arizona. In her role with the Network, Theresa supports an amazing team of individuals and works enthusiastically to support the growth and use of phenology data and resources curated by the USA-NPN, involvement in Nature’s Notebook, and a broader appreciation of phenology among scientists and non-scientists alike.

Theresa is also an Associate Professor in the School of Natural Resources and the Environment at the University of Arizona and has published over 70 peer-reviewed articles and book chapters in journals including Nature, Geophysical Research Letters, Global Change Biology, and Journal of Ecology. Her writing has  appeared in Scientific American, The Hill, and the Arizona Daily Star, and she has appeared in the PBS productions SciGirls and American Spring Live as well as on NPR and The Weather Channel. In 2022, she was recognized by the University of Arizona as a Woman of Impact.

Staff photo of Nathan Acosta, NPN Web Developer

Nathan Acosta
Web Developer

Nathan Acosta works on development, enhancement, and maintenance of the USA-NPN's web platforms. His duties mostly involve working on USA-NPN's websites making sure they function smoothly and are able to meet researcher's and observer's needs. He works closely with the rest of the team to make sure all aspects of the IT infrastructure work as intended and efficiently as possible.

Nathan graduated from The University of Arizona and got a B.S. in Computer Science with an Informatics minor and an Undergraduate Certificate in Cyber Security. He grew up in Arizona's neighboring state of Sonora, Mexico and he is passionate about researching and preserving the immense biodiversity of the Sonoran Desert. When he's away from the keyboard he likes to learn new cooking recipes, play the piano, and spend time with his family and dogs.

Samantha Brewer, Volunteer Engagement Coordinator, staff photo

Samantha Brewer
Volunteer Engagement Coordinator

Samantha Brewer communicates with new and existing Nature’s Notebook observers and organizations through engaging activities, newsletters, campaigns, and training materials. She coordinates with Local Phenology Leaders to strengthen their programs and assist in volunteer recruitment and retention strategies. She also works to identify communities that are underrepresented in the scientific field and offers guidance for them to develop their own Local Phenology Programs that fit the needs of their organizations and produce quality data. Samantha leads the Local Phenology Leader Certification Course, and supports the Local Phenology Leader Community of Practice.

Samantha earned her Bachelor’s and Master’s degrees in biology at Northern Arizona University. She has worked across the state of Arizona studying avian ecology, with her Master’s thesis focusing on Gray Hawk population changes along the San Pedro River. She also has a background in Education - teaching biology and ecology at both the college level and K-12 settings. Prior to working for the USA-NPN, she worked as an Educator and Certified Local Phenology Leader for the Reid Park Zoo in Tucson. In her free time, she loves cross-stitching, gaming, and running along The Loop trail. 

Ellen Denny, Monitoring Design and Data Coordinator, staff photo

Ellen Denny
Monitoring Design & Data Coordinator
Short CV

Ellen Denny coordinates the development of the USA-NPN protocols for the collection of standardized ground-based plant and animal phenology observations across the nation.  She also serves as a scientific data manager for the National Phenology Database, and as a global liason, helping to advise developing national phenology networks around the world, and working towards global integration of phenology data.
Ellen has a B.S. in Aquatic Biology from Brown University, and an M.F.S. (Forest Science) from the Yale School of the Environment (formerly Yale School of Forestry & Environmental Studies). Her professional interests began in marine invertebrate ecology, shifted to ecological restoration, and eventually landed in terrestrial ecosystem ecology. She spent a decade working as a field ecologist and data manager in the forests of New England before coming to the USA-NPN in 2008. Ellen lives in Kittery, Maine, and participates remotely in the Tucson-based National Coordinating Office.

Erin Posthumus, Outreach Coordinator, staff photo

Erin Posthumus
Partnerships & Projects Manager
(520) 314-7883
Short CV

Erin Posthumus manages USA-NPN projects that inform decisions and advance science. She serves as the USA-NPN lead for key partnerships including USFS, USFWS, NPS, and Audubon; coordinates activities to support the creation of new data products; and implements and oversees data collection campaigns at local to national scales. Erin oversees communications and works to establish new partnerships for the USA-NPN.

Erin received a B.A. in Environmental Biology from the University of Colorado at Boulder and a M.S. from the University of Arizona's School of Natural Resources and the Environment. With a background in wildlife conservation and management, she spent several years working as a wildlife field technician in locations across the country before serving in the Peace Corps in Vanuatu from 2007-09. Erin has been with the USA-NPN since 2010. Erin enjoys hiking, baking, and tending her small urban farm.

Jeff Switzer, Systems Analyst, staff photo

Jeff Switzer
Systems Analyst
(520) 621-1636

Jeff Switzer will be using his programming skills to enhance and debug all aspects of the USA-NPN's IT infrastructure. His duties range from solving problems with the mobile apps to creating features for the website to optimizing the database. He assists the USA-NPN team in making processes and functionalities more efficient and more adept to handling observer’s needs.  

Jeff graduated from the University of Wyoming with B.S. degrees in computer science and mathematics. As a graduate student, he researched resource-bounded dimension and joined a startup where he developed an electronic medical records system. He then spent two years teaching in Africa before joining the NPN team. When he's not coding you can find him camping, mountain biking, making music, and drinking tea.


Ram Dheeraj photo

Ram Dheeraj Kamarajugadda
Web Analyst Assistant

Ram Dheeraj is a graduate student at the University of Arizona majoring in Data Science. He is originally from Hyderabad, India, working with USA-NPN as a Web Analyst Assistant. He assists the USA-NPN team to enhance its Google Analytics platform. He usually likes to play chess and cricket in his free time.

Kai Enright staff photo

Kai Enright
Student Data & Analysis Assistant

Kai Enright is originally from Shakopee Minnesota, and moved to Tucson in 2018. He is currently a student at the University of Arizona majoring in Biology with an emphasis in organismal biology. Kai is digitizing and analyzing a long-term dataset on saguaro phenology from the Tucson basin. His hobbies include rock climbing and skateboarding. 

NPN Student Ava Lasater staff photo

Ava Lasater

Ava Lasater is an undergraduate student at the University of Arizona majoring in Bioinformatics and is in the Honors College. Ava is from Golden, Colorado, and is interested in climate change and how changes in the environment and ecology affect human health.

She is looking forward to getting involved on campus over the course of the year, specifically with volunteering and clubs in addition to research.

Mano Tainatongo staff photo

Mano Tainatongo
Student Administrative Assistant

Mano Tainatongo is an undergraduate student at the University of Arizona majoring in Natural Resources. Mano is from Tucson, Arizona and is working as student administrative assistant for the USA-NPN. Outside of school Mano enjoys hiking and camping all across Arizona.

McKinsey Tighe staff photo

McKinsey Tighe
Student Outreach Assistant

Hello! My name is McKinsey, and I'm a sophomore at the University of Arizona studying Natural Resources with an emphasis in Conservation Biology in hopes of becoming a Wildlife Biologist. I've been using Nature's Notebook for my studies since I began at UofA, and I'm ecstatic to be working with USA-NPN to help share their awesome projects!

Christian Willoughby

Christian Willoughby
SkillBridge Intern

I’m originally from Goldsboro, North Carolina and moved to Tucson in May of 2019. I’m currently waiting for my application to the U of A to be approved but hope to study Ecology and Environmental Biology in the fall, I enjoy hiking and learning about animals as well as their ecosystems. I also enjoy learning about plants and at one point and time grew various types of cactus. 


Jeremy Clark photo

Jeremy Clark
Embedded Entrepreneur for USA-NPN

Jeremy Clark is helping USA-NPN to develop a multiyear strategy to ensure that it thrives well into the future. Jeremy is a strategy advisor and business builder with experience at many successful research and innovation-centric companies including Xerox PARC and Comcast. He earned an MBA from the University of Chicago, and his functional experience covers technology research and innovation, strategy development, business model transformation, and product development.

Jeremy has recently been working to apply this experience to the sustainable development challenge for business. He took a career break in 2022 to study for an MSc in Sustainable Development from the University of Surrey in England, which definitely changed his frame of reference for what should be considered good growth! He enjoys hiking, biking, and any interactions with dogs, and he is increasingly fascinated by phenology and its amazing potential for informing climate change response.


Kerissa Fuccillo Battle

Kerissa Fuccillo Battle, PhD

Kerissa is a research ecologist and strategic advisor whose work is focused on catalyzing community science research and building capacity for organizations in the field of science and education. She has worked as a collaborator with the USA-NPN since 2010 and manages the New York Phenology Project. She is currently working with the USA-NPN team as a multi-agency strategic project manager for the Northeast Climate Adaptation Center funded project titled “Thermal Calendars for a Changing Climate.”  She lives in the Catskill Mountains of New York and loves to grow things. 


Gail Bishop, Gulf Coast Phenology Trail Coordinator, staff photo

Gail Bishop
Gulf Coast Phenology Trail Coordinator

Gail Bishop has called Ocean Springs home since 1986 although she has also lived in Florida, Alabama, and Kentucky. She retired from the National Park Service as a superintendent but spent much of her career in interpretation and education. She has volunteered for Habitat Stewards, Audubon, the NPS, and for the Gulf Coast Phenology Trail. She loves the northern Gulf Coast and appreciates the work that volunteers do to protect the natural resources.

Questions about the Trail, or about how to become a Trail partner? Contact Gail at

Jane Breckinridge staff photo

Jane Breckinridge
Oklahoma State Coordinator for Time to Restore: Connecting People, Plants, and Pollinators

Jane Breckinridge is the director of the Euchee Butterfly Farm located in Leonard, Oklahoma. She is also the co-director of the Tribal Alliance for Pollinators, which unites traditional ecological knowledge with cutting edge technical resources to create an innovative model for conservation and restoration of tribal lands. Jane leads the Oklahoma efforts for Time to Restore. 

David Gwin photo

David Gwin
Texas State Coordinator for Time to Restore: Connecting People, Plants, and Pollinators

David Gwin is the Texas State Coordinator for USA-NPN’s Time to Restore.  In this capacity, he works with stakeholders across the Lone Star State to identify, setup and monitor sites that generate better information about nectar availability and fruit production to ultimately help inform those working on pollinator restoration to know what to plant and when to harvest seed. 

David earned his Bachelor of Arts and Master of Science degrees from Oklahoma State University in Stillwater, Oklahoma.  After completing his formal education, he spent over three decades in professional public service with six Texas communities in developing, administering, and refining their local economies.  Since leaving municipal service, David has wholly devoted himself to his lifelong passion, which is better understanding, actively appreciating, and enthusiastically conserving our diverse natural resources.  He was certified as a Texas Master Naturalist in 2005 and has been an active participant in that statewide volunteer service effort in four different ecoregions of the state.  In his free time, David loves hiking, camping, and almost anything else that keeps him out in the wilder parts of Texas. 

Gina Lloyd staff photo

Gina Lloyd
Louisiana State Coordinator for Time to Restore: Connecting People, Plants, and Pollinators

Gina Lloyd has been working with citizen science programs in both a volunteer and professional capacity for over three years. She has trained volunteers for FrogWatch USA data collection walks since 2019 and regularly leads these walks with a large local network of citizen science volunteers and academics. Since beginning work at the Jean Lafitte Barataria Preserve, she has also helped develop volunteer training workshops and led data collection hikes for the Nature’s Notebook program. As the Louisiana State Coordinator for Time to Restore, Gina is working to establish several new Nature’s Notebook monitoring sites across the state in partnership with communities interested in tracking phenological changes.

Erin Zylstra photo

Erin Zylstra
Quantitative Ecologist

Erin Zylstra is a quantitative ecologist with Tucson Audubon Society, where she works with academic and federal partners to evaluate the effects of climate, land use change, and other factors on wildlife and plant populations. Erin is based in Tucson, Arizona and is currently working with the USA-NPN team on data analysis for the Time To Restore project.


Rachel Goland staff photo

Rachel Goland

Rachel Goland is excited to collaborate with USA-NPN and the US Forest Service on the Shifting Seasons project to better understand and support Forest Service needs for phenological information. Rachel received her B.S. in Environmental Science from Cornell University in 2020. She now lives in New York’s Adirondack Park where she works as a land manager for New York State. Outside of work, she enjoys exploring the wilderness on foot or by boat, foraging for fungi, and reading books of all genres. 

Georgia Murray staff photo

Georgia Murray

Georgia Murray is a Staff Scientist with the Appalachian Mountain Club. Previously she has conducted biogeochemical research for the Marine Biological Laboratory’s Ecosystem Center at Toolik, Alaska a Long-term Ecological Research site and worked at the University of Washington maintaining a long-term small watershed monitoring site within Olympic National Park. Georgia currently oversees Appalachian Mountain Club’s ambient air pollution program in cooperation with the U.S. Forest Service including mountain-based monitoring of cloud, rain, and stream water chemistry in Wilderness areas in the White Mountain National Forest. She also leads AMC’s plant phenology monitoring work using Nature’s Notebook, which incorporates community science, and conducts mountain climate research. Back in 2010, Georgia suggested "Nature's Notebook" as the name for the USA-NPN's data collection program - thank you, Georgia!