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Species · Maryland · BBS 2025 Release · 1966–2024

Blue-winged Warbler Population Trend in Maryland

All statesForest birds

Blue-winged Warbler in Maryland has declined: down 35% on the route-weighted index since 1971.

-35%Since 1971TrendPercent 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 →
21Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
49YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Blue-winged Warbler Trends in MarylandNotable 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 Blue-winged Warbler in Maryland. See the full index history below.

Blue-winged Warbler Population Forecast in Maryland

If the recent trend holds, Blue-winged Warbler in Maryland is projected to stay roughly flat through 2029, near 0.04 (95% range 0.00–0.11). A 5-year backtest shows a typical error of ±29.5%, 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 →
0.04Projected 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 →
0.00–0.1195% 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 →
±29.5%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, Blue-winged Warbler in Maryland is projected to stay roughly flat through 2029, near 0.04 (95% range 0.00–0.11). A 5-year backtest shows a typical error of ±29.5%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20250.040.000.11
20260.040.000.11
20270.040.000.11
20280.040.000.11
20290.040.000.11

Blue-winged Warbler Survey Routes in Maryland

Routes recording Blue-winged Warbler in Maryland.
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 →
Vindex119781978
Oldtown120191995
Potomac Park120221973
Williamsport120052002
Smithsburg120111975
Wolfsville120131970
Olney120241981
Pleasant Val119871977
Bachman Mill120071989
Eklo120161995
Randallstown120051977
Beltsville119751975
Madonna120142013
Earlton120142014
Pomfret119951989
Theodore119881975
Northeast119971968
Elkton119961996
Jennings119951995
Green Ridge120241995
Ijamsville120051994

Blue-winged Warbler Population Trend in Other States

alabamaarkansasconnecticutdelawaregeorgiaillinoisindianaiowakentuckymassachusettsmichiganminnesotamississippimissourinew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandtennesseevermontvirginiawest-virginiawisconsin

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