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Species · Maryland · BBS 2025 Release · 1966–2024

Prothonotary Warbler Population Trend in Maryland

All statesForest birds

Prothonotary Warbler in Maryland has surged: up 129% on the route-weighted index since 1968.

+129%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 →
36Routes 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 Prothonotary 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 →

Prothonotary Warbler has surged in Maryland: up 129% on the route-weighted index since 1968.

Prothonotary Warbler Population Forecast in Maryland

If the recent trend holds, Prothonotary Warbler in Maryland is projected to rise about 15% by 2029 — from 0.62 in 2024 to a central estimate of 0.71 (95% range 0.37–1.0). A 5-year backtest shows a typical error of ±19.2%, with 80% 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 →
0.37–1.095% 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 →
±19.2%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, Prothonotary Warbler in Maryland is projected to rise about 15% by 2029 — from 0.62 in 2024 to a central estimate of 0.71 (95% range 0.37–1.0). A 5-year backtest shows a typical error of ±19.2%, 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 →
20250.690.351.0
20260.690.361.0
20270.700.361.0
20280.700.371.0
20290.710.371.0

Prothonotary Warbler Survey Routes in Maryland

Routes recording Prothonotary 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 →
Berlin720241980
Cokesbury520241972
Furnace Town520242015
Honga320241966
Sinepuxent319771973
Snow Hill319761966
Indiantown220141977
Earlton220192014
Piney Neck220171972
Harmony220171966
Davidsnville220231993
Island Creek220242001
Williamsport120242017
Olney120022002
Walnut120051999
Van Bibber120111967
Largo119751967
Cheltenham119661966
Broomes Isl119891966
Pt Republic119891986
La Plata120091966
Hughesville120232023
Pomonkey120241967
Pomfret120231966
Theodore119681968

Prothonotary Warbler Population Trend in Other States

alabamaarkansasdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamichiganminnesotamississippimissourinew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniasouth-carolinatennesseetexasvirginiawest-virginiawisconsin

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