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Species · Pennsylvania · BBS 2025 Release · 1966–2024

Mourning Warbler Population Trend in Pennsylvania

All statesForest birds

Mourning Warbler in Pennsylvania has edged down: down 14% on the route-weighted index since 1968.

-14%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 →
34Routes 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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Mourning Warbler Trends in PennsylvaniaNotable 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 Mourning Warbler in Pennsylvania. See the full index history below.

Mourning Warbler Population Forecast in Pennsylvania

If the recent trend holds, Mourning Warbler in Pennsylvania is projected to rise about 74% by 2029 — from 0.09 in 2024 to a central estimate of 0.16 (95% range 0.05–0.26). A 5-year backtest shows a typical error of ±107.9%, with 60% of held-out values landing inside the 95% band.

+74%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 →
0.16Projected 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 →
0.05–0.2695% 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 →
±107.9%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, Mourning Warbler in Pennsylvania is projected to rise about 74% by 2029 — from 0.09 in 2024 to a central estimate of 0.16 (95% range 0.05–0.26). A 5-year backtest shows a typical error of ±107.9%, with 60% 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 →
20250.150.050.26
20260.150.050.26
20270.150.050.26
20280.160.050.26
20290.160.050.26

Mourning Warbler Survey Routes in Pennsylvania

Routes recording Mourning Warbler in Pennsylvania.
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 →
Akeley419741966
Odin420241992
Arnot420182000
Susquehanna320211972
Ansonia220242002
Little Marsh220231999
Mawr Glen220211982
Marsh Hill220131990
Harmonsburg120131971
Ferris Crnrs120241970
Whig Hill120221966
Teepleville120061988
Sigel120092009
Lynch120021992
Ellenton120211998
N Pine Grove120071969
Pottersdale119941994
Betula120211976
Russell City120171968
Starlight 2120222022
Eldred120221987
Rasselas120132001
Roulette120161977
Logue120221996
Rosecrans119871979

Mourning Warbler Population Trend in Other States

connecticutillinoisindianamainemarylandmassachusettsmichiganminnesotanew-hampshirenew-yorknorth-dakotaohiovermontwest-virginiawisconsin

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