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Mark Fallon, Director

Mark came to Briar Bush in January 2003 and became Director in 2020. He holds a BA in Zoology and French from Connecticut College. From the coasts and mountains of New England to the Rockies of Wyoming to the Delaware River, Mark has spent his professional life teaching, coaching and interpreting in the outdoors. Mark leads our talented team in all aspects of operations and projects. For 18 years as Senior Naturalist, Mark answered the public's questions about nature, taught programs, worked with volunteers, and developed a thorough knowledge of native and invasive exotics plants and horticulture. He has managed such projects as the Nature Playscape, Members' Grove and Pond restoration. Originally from Massachusetts, Mark now lives with his family in Mt. Airy, Philadelphia.

Estelle Allen, Program and Guest Services Coordinator


Estelle Allen joined the Briar Bush team in October 2022 as the Program and Guest Services Coordinator. Estelle spent 35 years at a major telecommunications company holding positions focusing on customer service and project coordination. Following retirement, she worked with the Abington Township Community Police Division providing support to the Police Athletic League, and later accepted a Customer Service position with AARP. She is committed to providing service to others, most importantly her church, The Abington Youth Aid Panel, and Montgomery County Senior Services.

Estelle lives in Glenside PA where she and her husband raised their 2 children. She cherishes the time she has with their 2 grandchildren. She enjoys family, bowling, traveling, planning, and hosting group activities for family and friends.

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Sarah Busby, Part-Time Educator

Sarah is a recent graduate of Drexel University and is excited to have joined the Briar Bush team this March! She earned her BS in Biology with a concentration in Ecology, Evolution, and Genomics in June 2023. Her previous work at the Academy of Natural Sciences and Willistown Conservation Trust focused on watershed ecology and water quality monitoring within the Delaware Watershed. From macroinvertebrates to megafauna, she is endlessly fascinated with the beauty and complexity of nature and desires to foster this fascination in others. She is looking forward to bringing this passion to her role as an educator at Briar Bush. Originally from the South Shore of Massachusetts, she now lives in West Philadelphia, where she can typically be found hosting board game nights, convincing her city friends to go on more hikes, and juggling too many crafting hobbies.

Melissa Eldridge, Program and Summer Camp Director

Melissa holds a B.S. in Recreation Management and minors in Biology and Environmental Studies from Lock Haven University. Before joining the full-time staff in 2014, Melissa had worked at Briar Bush for two summers as a Camp Counselor. Now as the Program and Summer Camp Director, she is responsible for developing and updating programs for children, families, adults, and groups, as well as directing the Summer Camp program. In 2016, she received the Daisy S. Klinedinst Memorial Award for her continued dedication in environmental education from the Pennsylvania Association of Environmental Educators. Melissa considers herself a naturally curious person and a life-long learner who enjoys spending time in nature hiking, camping, kayaking, and exploring. She resides in Blue Bell with her husband, Scott.

Katie Fisk, Animal Curator and Educator

Katie has been with Briar Bush since 2009. She received her BS in wildlife biology from Colorado State University and an MS degree in Environmental Education and Interpretation from the University of Wisconsin Stevens Point. Her background consists of work with both people and animals through organizations such as the US Fish & Wildlife Service, Tampa's Lowry Park Zoo, Busch Gardens Tampa Bay, and various bird research groups. At Briar Bush, Katie loves the variety of teaching audiences of all ages and caring for the animal ambassador collection along with an amazing group of dedicated volunteers.  When not working, you might find her hiking, kayaking, or working in her native garden.

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Karen Foster, Development and Event Coordinator

Karen joined the Briar Bush team in the fall of 2016 as an Environmental Educator and enjoys working with its dedicated and knowledgeable staff. She brought with her a B.S. in Ecology and a variety of experiences in outdoor education, after-school and summer camp programming, curriculum development, and environmental research. Karen began her career as an Environmental Educator at Churchville Nature Center followed by time in New Mexico as part of the USDA’s environmental research program. Since then, Karen has worked with the Fairmount Park Commission, the Schuylkill Center for Environmental Education, and Philly U. as part of an environmental research and education project. Karen's current position at Briar Bush includes fundraising, special event planning, community outreach, marketing and communications. Karen lives in Abington Township with her family and loves being a part of her local nature center. 

Ehren Gross, Senior Naturalist

An experienced educator, Ehren has been in the field of Environmental Education since 2002. Before Briar Bush, he worked in various National Parks as a Park Ranger giving talks, leading guided hikes and developing Enviro Education programs for the public. He is most comfortable in front of an audience performing live animal shows or in-classroom demonstrations. Ehren has his Bachelor's degree in Environmental Science from West Virginia Wesleyan College and a Masters in Environmental Education from Arcadia University. In his free time he loves reading nature stories, astronomy, and bush crafting. Ehren lives in Abington with his wife, daughters, chickens and colony of bees.

Heidi Malizia, Environmental Educator

Heidi holds a degree in Elementary Education with a concentration in environmental science from Penn State University. Before Briar Bush, Heidi taught 3rd grade, where she loved teaching but missed the outdoors.  After an internship at Shaver’s Creek Environmental Center, she was hired as the Outreach Coordinator at Great Valley Nature Center. While there, she developed the Head Start into Nature Program, chaired the annual auction, taught summer camp and outdoor school programs, facilitated team-building exercises, ran teacher workshops, and led adventure trips. Heidi began her journey at Briar Bush in 2009 as a part-time weekend educator. Today, she can be found leading the Magic Mornings and Nature Pioneer preschool programs on the property. She also coordinates and creates the programs for all the Montgomery County Head Start and Pre-K Counts programs and leads adventure summer camps. Heidi is the staff liaison for the Feather Our Nest Auction and Gala development team. In her spare time, Heidi loves being outdoors kayaking, hiking, and going on adventures with her husband, three daughters, and dog.

Kyrstin Schwarz, Part-Time Educator

Kyrstin has a Bachelor’s Degree in Conservation and Wildlife Management with a minor in Education. While in college and since graduating, Kyrstin has worked as a tutor, a pet groomer, a camp counselor, and a substitute teacher. Kyrstin has also worked with different animals from cats to cows to giraffes. She loves spending time outside with family and friends, camping, traveling the world, and wildlife photography. When she’s not outside, Kyrstin spends her time reading, painting, and playing games. She grew up in New Jersey and moved to Pennsylvania in 2017. Kyrstin now lives in Doylestown with her fiance, Jeff, and her calico cat, Cheyenne.

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