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Species · Maryland · BBS 2025 Release · 1966–2024

Yellow Warbler Population Trend in Maryland

All statesForest birds

Yellow Warbler in Maryland has surged: up 99% on the route-weighted index since 1968.

+99%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 →
68Routes 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 Yellow 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 →

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 Warbler has surged in Maryland: up 99% on the route-weighted index since 1968.

Yellow Warbler Population Forecast in Maryland

If the recent trend holds, Yellow Warbler in Maryland is projected to rise about 26% by 2029 — from 1.7 in 2024 to a central estimate of 2.1 (95% range 1.0–3.3). A 5-year backtest shows a typical error of ±71.2%, with 80% of held-out values landing inside the 95% band.

+26%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 →
2.1Projected 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 →
1.0–3.395% 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 →
±71.2%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 Warbler in Maryland is projected to rise about 26% by 2029 — from 1.7 in 2024 to a central estimate of 2.1 (95% range 1.0–3.3). A 5-year backtest shows a typical error of ±71.2%, 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 →
20252.10.973.2
20262.10.983.2
20272.10.993.2
20282.11.03.3
20292.11.03.3

Yellow Warbler Survey Routes in Maryland

Routes recording Yellow 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 →
Jennings1820241995
Finzel1420241995
Steyer820241996
Potomac Park620241970
Pomfret420061974
Earlton420242014
Smithsburg320141975
Emmitsburg320241969
Pleasant Val320241969
Eklo320181970
Randallstown320131972
Walnut320242024
La Plata320092009
Grove Neck319961992
Green Ridge320241995
Bald Friar319961992
Floyd220241966
Vindex220241966
Bachman Mill220241966
Upper Xrds220071966
Beltsville220021966
Northeast220061969
Golden Hill220051971
Fair Hill219961992
Accident 2220242018

Yellow Warbler Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckymainemassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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