In the forest, life is often heard before it’s seen. Hikers and hunters are familiar with the creature chorus: cicada trills and tree frog chirps, wood thrush rhythms and whip-poor-will chants. This unique blend of animal noises is what scientists call the forest soundscape. And listening carefully to the soundscape is sometimes the best way to determine whether a forest is healthy.
Deep inside the forest-wetlands of northern Wisconsin, Angela Waupochick is listening.
A Ph.D. student in forest and wildlife ecology, Waupochick is among a growing number of scientists using a simple technique called bioacoustic monitoring to record forest soundscapes. The equipment they employ is relatively inexpensive and unobtrusive, but it can capture the sound signatures of all animals that are present — even the most elusive ones.
“Bioacoustic monitoring can show us even minute details about wildlife that might be harder to see, for example, nocturnal birds or bats, without having to disturb the animals,” says Zuzana Burivalova, an assistant professor in the Department of Forest and Wildlife Ecology and the Nelson Institute for Environmental Studies. She’s also one of Waupochick’s dissertation advisors.
With bioacoustic monitoring, researchers place small recorders in the forest. They then use computer software to parse out the captured sound signatures of different species. This information can reveal a lot about the biodiversity and overall health of the forest ecosystem. For instance, knowing which species are present — and at what times — can help land managers determine the most effective ways to protect their natural resources.
Waupochick is using bioacoustic monitoring in a forest-wetland research project in the Menominee and Stockbridge-Munsee Tribal Lands near Keshena, in northern Wisconsin. Her goal is to find the best conservation strategies for these black ash–dominated ecosystems because they are widespread in the area and a culturally significant tribal land resource.
“The Menominee word for wetland or swamp is maskīk (pronounced ma-skeek), which is also our word for medicine,” explains Ben Grignon, a traditional arts teacher at the Menominee Indian High School and member of the Menominee Language and Culture Commission. “When we understand the Menominee worldview through our language, we gain a deeper understanding and appreciation of our traditional ecological knowledge.”
Waupochick is concerned that, even though these areas are ecologically and culturally important, they are not a priority for management.
“The forested wetlands that have survived through [past] disregard for these systems will now be even more reduced by the emerald ash borer,” she says. “Since tribes have a significant amount of land holdings and forested wetlands, we need to acknowledge the importance of wetlands, and I am hoping, through this research, we are able to implement some degree of successful mitigation. Perhaps we can maintain some of the functionality for habitat, for the integrity of tribal forests. I am building my base to manage these systems in the long-term.”
By recording the forest soundscape, Waupochick is analyzing which species are present. She plans to combine this information with tree physiology data to evaluate existing management practices and provide conservation recommendations to address future disturbances. To complete this work, she has partnered with two indigenous communities in northeastern Wisconsin and researchers from the United States Forest Service.
At the start of 2020, Waupochick was planning to launch her first field season in late spring. Then came the global COVID-19 pandemic. Due to travel restrictions, the team of assistants she had assembled could no longer help her install and maintain her experiment.
“I had no choice but to recruit my 16-year-old son to help tackle the fieldwork,” Waupochick says.
Waupochick’s son, Saswaen, never planned to spend his summer plodding through wetlands with recorders, 12-volt batteries, solar panels, and tree sap flow meters strapped to his back. But mother and son made a wonderful team. Saswaen came to truly enjoy participating in the research, and he learned a lot.
“Mostly, I like being out in the woods,” he says, “I wouldn’t want to work at a restaurant or store now that I am being paid to be outside. Both of my parents work in forestry, so I knew they plan how the forest is cut, and they worry about plants that are not supposed to be here and insects that kill trees. Now I think I can identify all of the trees in the forest by bark, not leaf, and know where to expect certain trees to be growing.”
Waupochick also recruited students in a trade class at the Menominee Indian High School to help build heat sensors for measuring characteristics of tree physiology. The sensors will detect sap flux density, which will help her understand the movement of water through the trees, a process known as transpiration. Then she’ll be able to compare relationships between a forest’s water budget and the presence of biodiversity at various sites that are exposed to different management techniques.
For example, Waupochick’s study aims to assess whether selective cutting — a management practice used to mitigate the devastation that would be caused by an emerald ash borer invasion — is the most effective way to protect forested wetlands. Waupochick’s study can also help determine whether changes in biodiversity are tied to alterations in the forest’s water budget that stem from climate change.