“Only a freak ornithologist would think of leaving the trails for more than a few feet. The discouragingly dense tangles in which Bicknell’s Thrushes dwell have kept their habits long wrapped in mystery.” – Dr. George Wallace, 1939
In June 1992, on the fog-shrouded ridgeline of Vermont’s highest peak, VCE cofounder and Director Emeritus Chris Rimmer captured, banded, and released a small songbird. Over three decades later and nearly 11,000 birds banded, our data are helping to shed light on population changes, demographics, and avian health.
© Alden Wicker
Threatened by human-related development and climate change, montane conifer forests of the Northeast are like islands in the sky, with distinct assemblages of plant and bird species. The weather up there can be harsh. The blackflies can be horrendous. The habitat—thickets of fir and spruce—is virtually impenetrable and often dripping with moisture. Our biologists and bird banders have been snowed on in June.
Michael Hallworth plays callback to tempt a Blackpoll Warbler into a mist net. © Alden Wicker
And still, we go back, year after year, to Vermont’s highest peak, looking for information on what threatens montane birds, and what we can do to protect them.
Our scientists, with the help of student interns and volunteers, have operated mist nets along the ridgeline of Mt. Mansfield each summer since 1992. They rise before the sun at 3:30 AM to ready for the dawn chorus. They set out harmless and invisible mist nets hung between poles along trails, and may play birdsong from a speaker to tempt birds into the nets.
Anna Peel takes a bird out of a mist net. © Michael Sargent
Checking the nets regularly, our trained bird banders carefully take each captured bird to our bird-banding station, where they place a tiny aluminum bracelet with a unique set of nine digits, like an avian social security number, on each bird’s right leg, plus colored bands for identification. The birds are measured, weighed, and for some individuals, tiny droplet of blood and a single feather may be taken for chemical analysis. With all the data stored safely with the scientists, the bird is released back to the wild.
© Alden Wicker
Every year, we band nearly 1,000 birds to help us understand changes in the breeding bird community with weather, climate, forest changes, and more thanks to the Forest Ecosystem Monitoring Cooperative. Our findings have been applied throughout the Northeast in the management of state and national forests, alpine ski areas, timberlands, and ridgeline development projects.
Mount Mansfield Timeline
1992: Chris Rimmer banded his first Bicknell’s Thrush and began to study population density on the ridgeline with partners at Manomet Conservation Sciences.
1994: First Blackpoll Warbler banded. VCE established study areas on other mountains.
1995: First Swainson’s Thrush banded, migration banding started. VCE expanded from one study plot on the summit to having plots in Ranch Brook Valley and on the ski area, as well as a second Ridgeline plot south of the original plot, with the help of an expanded crew of field technicians. First radio transmitters were attached to Bicknell’s Thrush.
1996: VCE expanded the species it was banding to track more demographics, including Yellow-rumped Warbler, American Robin, Slate-colored Junco, Purple Finch, and White-throated Sparrow.
1997: Migration banding ended. Demographic work began on Stratton Mountain. VCE scientists observed for the first time multiple male feeders at nests on Stratton and Mansfield.
2000: Hearing from atmospheric scientists that high levels of mercury precipitates onto mountains, VCE scientists began sampling songbirds for mercury to challenge the common scientific understanding that—while aquatic birds suffer from mercury poisoning—it was not a problem for terrestrial birds.
2009: McFarland deployed the first light-level geolocator was deployed on Bicknell’s Thrush.
2012: Began full community capture-recapture banding.
2013: First deployment of light-level geolocators units on Blackpoll Warbler, with Bill DeLuca.
2016: First deployment of autonomous recording units (ARUs) for spring phenology monitoring.
2021: First GPS units on Bicknell’s Thrush.
2023: Desiree Narango took over as principal investigator. First nanotags on Bicknell’s Thrush, Swainson’s Thrush and White-throated Sparrow. First season collecting data on insect prey availability.
2025: First season putting barometric pressure tags on Blackpoll Warblers and Bicknell’s Thrush.
