A project of

Yellow-bellied Flycatcher

The Moss Tyrant

This elusive denizen of muskeg and boggy boreal forests spends a few short months in our region before retiring to its winter home in Central America. Its reclusive nature and breeding preference for thick, damp forests makes it difficult to study. As a consequence, we still know very little about the life-history habitats of the Yellow-bellied Flycatcher. Anyone like mosquitoes, biting flies, soggy feet and looking for a new side project?

The State of Yellow-bellied Flycatchers

Northeastern United States: Gradually declining

Yellow-bellied Flycatcher was not one of the original Mountain Birdwatch species (2000-2010), but so little is known about this species that we felt compelled to contribute to the scientific knowledge of the Moss Tyrant. Similar to Bicknell’s Thrush, Yellow-bellied Flycatcher populations in our region appear to be gradually declining (mean annual regional trend = -2.45%, 95% Bayesian credible interval = -3.75% to -1.10%). Strikingly similar to Bicknell’s Thrush, these declines are greatest in the Catskills of New York where this species has gone from uncommon (24 individuals detected in 2011) to almost absent (2 individual birds detected in 2019). The North American Breeding Bird survey reports an annual decline of approximately 4% for Yellow-bellied Flycatchers in Vermont and New Hampshire, and overall declining trends (-0.8% per year) for the Atlantic Northern Forest (the northeastern U.S. plus Southeast Canada).

The mean (thick, dark orange line) annual estimate of the Yellow-bellied Flycatcher local population size within the area immediately surrounding ~750 Mountain Birdwatch sampling stations. The vertical orange bars present the 95% Bayesian credible interval (a measure of uncertainty) surrounding those mean annual estimates.

Mean annual population trends (below) for Yellow-bellied Flycatcher from 2011 through 2019. A red dot indicates strong evidence for a negative trend. An orange dot indicates a likely negative trend. A trend of -2%, for example, indicates that the number of Yellow-bellied Flycatchers in our study area has declined by an average of 2% each year from 2011 through 2019.
RegionMean annual trend95% credible interval
All regions combined -2.45(-3.75, -1.10)
New York (Adirondacks) -0.39(-2.48, 1.76)
Vermont -4.13(-6.72, -1.44)
New Hampshire -1.20(-2.89, 0.57)
Maine -3.13(-5.87, -0.83)

Note: trends for the Catskills, where relatively few Yellow-bellied Flycatchers are detected, are not shown.

Globally: Increasing

The vast majority (>95%) of Yellow-bellied Flycatchers breed in Canada where this species is increasing in numbers. The discovery of new breeding populations recently in eastern Alaska also suggests a global population growing northward.

Yellow-bellied Flycatcher numbers have increased across Canada and the U.S. according to the North American Breeding Bird Survey. Figure provided by the USGS Breeding Bird Survey.

Opportunities for Conservation

Scientists have not identified any specific management and conservation actions to benefit the health of Yellow-bellied Flycatcher populations. As is true of most species, the most important general threat to Yellow-bellied Flycatcher is probably habitat loss and climate change. Recent climate modeling predicts that Yellow-bellied Flycatchers will be absent from the lower 48 U.S. states by ~2080, and that 73% of its current breeding range will become unoccupied as this species moves northward. More scientific research into the natural history of Yellow-bellied Flycatcher would help us better understand the habitat features required for survival and reproduction.

State of Mountain Birds