In 2019 and 2020, Maine Audubon partnered with the Kennebec Estuary Land Trust, the Seven Lakes Alliance, the Stanton Bird Club, and Midcoast Conservancy to test the efficacy of using remote acoustic recording devices, or song meters, to detect the presence of breeding birds at four different Demonstration Forests – in West Bath, Jefferson, Vienna, and Monmouth/Litchfield. The goal of this project was to evaluate whether we could use song meters to track changes in breeding bird presence in response to different forest management practices promoted by FFMB.
With the help of our partners, the song meters were set out in early May and rotated for two months among forest sites that represented important habitat features for birds and other wildlife – such as snags, small canopy gaps, riparian areas, standing and down woody material, mature older trees, and mixed-aged stands. We were interested in the overall species richness (number of species) associated with habitat features across each property, and also focused attention on 20 priority species of conservation interest.
Along with posting the song meters, we recruited a few hardy volunteers to identify birds on-site through point counts, and others to listen to the recordings to identify bird songs. We then analyzed the recordings using sophisticated software and compared lists of birds identified using the software with the point counts and volunteer listening. While each of the lists was slightly different, we ultimately concluded that using the software was the most efficient. It was difficult to recruit volunteers that were both confident in their auditory identification skills and willing to head out into the woods at 4:00 in the morning, and those volunteers that listened to recordings found it sometimes difficult to identify the songs without being able to see what habitat the bird was singing from.
In all, we identified 131 species across the four Demonstration Forests. In some cases we noted specific species associated with important FFMB habitat features. For example, girdling trees to become snags helped attract many woodpeckers and other cavity nesters at Hidden Valley Nature Center, and creating small canopy gaps at Sewall Woods attracted Chestnut-sided Warblers, Mourning Warblers, and Eastern Wood Peewees. An older pond-side forest stand that had not been recently harvested at Woodbury Nature Sanctuary, featuring hardwood and softwood stands, riparian habitat, and a significant number of snags, supported 54 different species, confirming that structurally complex forests support a rich bird life. Other less structurally complex survey points had fewer species – such as the 24-28 species found at each of the survey points in the single-story, intermediate-aged hardwood forest stands at Kelly Woods.
In 2024 and 2025 we set out song meters in three more sites, all in the Bethel area, to collect baseline data on bird presence before wildlife-friendly forest management was scheduled to occur, with the hope of comparing that information with new data collected 5-10+ years after harvesting. Fortunately, the software analyses have become much faster and more reliable, though definitely not foolproof (for anyone that has used Cornell’s Merlin audio identification tool, you know what we’re talking about!).
Altogether, the song meters recorded 72 different bird species from the three sites, 49 of which are likely breeding on location. Each species that was identified with confidence at sites were broken down into three categories: Breeders (and likely breeders), migrants/visitors, or possible migrant/visitors. Birds with multiple confident detections in both the early and late breeding season windows (late May/early June and late June) were almost certainly breeding on site and considered breeders. Species with multiple confident detections in one breeding season window were considered migrants or visitors to the site. Species that were detected maybe once or had a lower confidence of identification by song were listed as possible migrant/visitor.
In 2026, we set out nine song meters within different forest types and stands at the Rumford Community Forest to gather data on which bird species can be found there as a baseline before undertaking additional habitat enhancement forestry activities recommended by the New England Forestry Foundation and its Exemplary Forestry program (similar to Maine Audubon’s FFMB program). Some thinning, especially of young beech, has already occurred there and the song meter data should help inform how those forest practices are influencing bird species presence right now.
We hope to use results from each of these surveys to help us track changes in bird communities and priority species over time in response to forest management, and inform recommendations we provide to private woodland owners, foresters, and loggers through the FFMB program.
