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Species · Maryland · BBS 2025 Release · 1966–2024

Black-and-white Warbler Population Trend in Maryland

All statesForest birds

Black-and-white Warbler in Maryland has held roughly steady: up 3% on the route-weighted index since 1968.

+3%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 →
59Routes 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 →
58YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Black-and-white 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 Black-and-white Warbler in Maryland. See the full index history below.

Black-and-white Warbler Population Forecast in Maryland

If the recent trend holds, Black-and-white Warbler in Maryland is projected to fall about 23% by 2029 — from 0.88 in 2024 to a central estimate of 0.68 (95% range 0.32–1.0). A 5-year backtest shows a typical error of ±26.4%, with 80% of held-out values landing inside the 95% band.

-23%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 →
0.68Projected 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 →
0.32–1.095% 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 →
±26.4%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, Black-and-white Warbler in Maryland is projected to fall about 23% by 2029 — from 0.88 in 2024 to a central estimate of 0.68 (95% range 0.32–1.0). A 5-year backtest shows a typical error of ±26.4%, with 80% 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 →
20250.670.321.0
20260.670.321.0
20270.670.321.0
20280.670.321.0
20290.680.321.0

Black-and-white Warbler Survey Routes in Maryland

Routes recording Black-and-white 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 →
Finzel1720241995
Matthews1020151966
Furnace Town620232015
Jennings520241996
Berlin420241980
Largo219771967
Hughesville220241967
Pomonkey220241966
Pomfret220241966
Floyd120211966
Mt Nebo119911969
Vindex120211966
Oldtown120241971
Potomac Park120231975
Bald Friar119931993
Smithsburg120131977
Wolfsville120191986
Olney120241987
Warfieldsbrg120141966
Bachman Mill120241982
Eklo120181977
Randallstown120001990
Walnut120062006
Van Bibber120021983
Jones119681968

Black-and-white Warbler Population Trend in Other States

alabamaarkansascaliforniaconnecticutdelawaregeorgiaillinoisindianakansaskentuckylouisianamainemassachusettsmichiganminnesotamississippimissourinebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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