BirdAnalyst
Species · BCR 4 · BBS 2025 Release · 1966–2024

Yellow-bellied Flycatcher In BCR 4

All regionsBCR 4Aerial insectivores

Yellow-bellied Flycatcher in BCR 4 has surged: up 18× on the route-weighted index since 1996.

18×Since 1996TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
14Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
28YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Yellow-bellied Flycatcher has surged in BCR 4: up 18× on the route-weighted index since 1996.

Yellow-bellied Flycatcher In BCR 4 Population Forecast

If the recent trend holds, Yellow-bellied Flycatcher in BCR 4 is projected to fall about 15% by 2029 — from 0.83 in 2024 to a central estimate of 0.71 (95% range 0.48–0.93). A 5-year backtest shows a typical error of ±38.4%, with 20% of held-out values landing inside the 95% band.

-15%Change by 2029TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
0.71Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.48–0.9395% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±38.4%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
If the recent trend holds, Yellow-bellied Flycatcher in BCR 4 is projected to fall about 15% by 2029 — from 0.83 in 2024 to a central estimate of 0.71 (95% range 0.48–0.93). A 5-year backtest shows a typical error of ±38.4%, with 20% of held-out values landing inside the 95% band.19942029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20250.620.400.85
20260.640.420.87
20270.670.440.89
20280.690.460.91
20290.710.480.93

Routes In BCR 4

Routes recording Yellow-bellied Flycatcher in BCR 4.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
Mt. FairplayALASKA172024
ChickenALASKA72024
EagleALASKA42024
Chatanika RALASKA42023
Birch LakeALASKA22019
MonahanALASKA22010
Kanuti CanynALASKA22024
LivengoodALASKA12021
SlanaALASKA12017
Tower BluffsALASKA12022
NorthwayALASKA12019
SourdoughALASKA11995
Kanuti LakeALASKA12013
Nabesna RoadALASKA12014

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.