BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Bay-breasted Warbler

ParulidaeForest birdsSetophaga castanea

Bay-breasted Warbler has collapsed: down 87% on the route-weighted index since 1968.

-87%Since 1968TrendPercent 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 →
117RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
58Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the Bay-breasted Warbler

The Bay-breasted Warbler (Setophaga castanea) is a North American member of the Wood-Warblers (Parulidae). In this analysis it is grouped with the forest birds.

Size
4.5–5.5 in long (11–14 cm) — a small, active songbird (typical for the family)
Habitat
Woodlands and forest edges, including wooded suburbs and parks.
Diet
Insects and spiders gleaned from foliage and bark, with seeds and berries in season.
Range
Recorded on 117 Breeding Bird Survey routes across 8 states, most concentrated in the Atlantic Northern Forest.
Family
Parulidae · Forest birds

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

No notable trend signals for Bay-breasted Warbler. See the full index history below.

Bay-breasted Warbler Population Forecast

If the recent trend holds, Bay-breasted Warbler is projected to stay roughly flat through 2029, near 0.00 (95% range 0.00–0.02). A 5-year backtest shows a typical error of ±46.6%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.00Projected 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 →
0.00–0.0295% 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 →
±46.6%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, Bay-breasted Warbler is projected to stay roughly flat through 2029, near 0.00 (95% range 0.00–0.02). A 5-year backtest shows a typical error of ±46.6%, with 100% of held-out values landing inside the 95% band.19662029
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 →
20250.000.000.02
20260.000.000.02
20270.000.000.02
20280.000.000.02
20290.000.000.02

Where the Bay-breasted Warbler Is Detected

BBS routes recording Bay-breasted Warbler, sized by most recent count.

Bay-breasted Warbler Population Trend by State

Bay-breasted Warbler population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Maine-74%197157
Michigan+68%198716
Minnesota-56%197613
New Hampshire-82%196812
New York-13%197414
Pennsylvaniainsufficient datan/a1
Vermontinsufficient datan/a3
Wisconsininsufficient datan/a1

Bay-breasted Warbler Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Bay-breasted Warbler population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Boreal Hardwood Transition-14%197630
Atlantic Northern Forest-82%196885

Bay-breasted Warbler Conservation Status

Our route-weighted index shows it down about 87% since 1968.

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.