The State of Yellow-bellied Flycatchers
Regionally: Slightly declining
The mean (thick, dark line) annual estimate of Yellow-bellied Flycatcher abundance—calculated as the annual sum of estimated Yellow-bellied Flycatcher within the local area (a 4-hectare circle) surrounding all 791 Mountain Birdwatch sampling stations. The thinner, lighter lines represent less probable estimates of the annual abundance.
Yellow-bellied Flycatcher was not one of the original Mountain Birdwatch species monitored between 2000 and 2010, but so little is known about this species that we felt compelled to contribute to the scientific knowledge of the Moss Tyrant. Yellow-bellied Flycatcher populations in our region appear to have declined in recent years across the Mountain Birdwatch region (mean annual regional trend = -2.22%, 80% Bayesian credible interval = -3.26% to -1.17%). Declines are substantial in the Catskills of New York (mean annual regional trend = -9.49%) where this species has gone from uncommon (46 individuals detected in 2011) to just 9 individual birds detected in 2023.
Mean annual population trends and population change (with 80% Bayesian credible intervals [CRI]) for Yellow-bellied Flycatcher from 2010 through 2023. A red dot
indicates strong evidence for a negative trend. An orange dot 
indicates weak evidence for a negative trend. Strong evidence is suggested for a trend when the 80% CRI does not include zero.
| Region | Mean annual trend (%) | Trend 80% CRI | Probability of decrease | Probability of increase | Population change (%) 2010-2023 | Population change (80% CRI) |
|---|---|---|---|---|---|---|
| All regions | -2.22 | (-3.26, -1.17) | 0.99 | 0.01 | -25.27 | (-35.01, -14.23) |
| New York (Catskills) | -9.49 | (-12.83, -5.93) | >0.99 | <0.01 | -72.63 | (-83.21, -54.84) |
| New York (Adirondacks) |  -0.63 | (-2.13, 0.83) | 0.70 | 0.29 | -7.84 | (-24.38, 11.34) |
| Vermont | -2.64 | (-4.16, -1.10) | 0.99 | 0.01 | -29.35 | (-42.41, -13.39) |
| New Hampshire | -1.86 | (-3.08, -0.61) | 0.97 | 0.03 | -21.66 | (-33.46, -7.59) |
| Maine | -2.97 | (-4.51, -1.43) | 0.99 | 0.01 | -32.40 | (-45.14, -17.13) |
Globally: Increasing
The vast majority (>95%) of Yellow-bellied Flycatchers breed in Canada where this species is increasing in numbers, particularly in the northern and western part of their range. The discovery of new breeding populations recently in eastern Alaska also suggests a global population growing northward. Yellow-bellied Flycatchers are rarely detected during USGS Breeding Bird Surveys in the northeastern U.S., and eBird trends are only available for the nonbreeding season where they appear to be becoming more common. This nonbreeding season increase may be driven by the increasing number of Yellow-bellied Flycatchers coming from the northwestern portion of this species’ range.
