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Species · Pennsylvania · BBS 2026 Release · 1966–2025

Purple Martin Population Trend in Pennsylvania

All statesAerial insectivores

Purple Martin in Pennsylvania has declined: down 40% on the route-weighted index since 1968.

-40%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 →
107Routes 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 →
59YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Purple Martin 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 Purple Martin in Pennsylvania. See the full index history below.

Purple Martin Population Forecast in Pennsylvania

If the recent trend holds, Purple Martin in Pennsylvania is projected to fall about 82% by 2030 — from 2.5 in 2025 to a central estimate of 0.45 (95% range 0.00–1.9). A 5-year backtest shows a typical error of ±84.4%, with 40% of held-out values landing inside the 95% band.

-82%Change by 2030TrendPercent 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 →
0.45Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1.995% 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 →
±84.4%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, Purple Martin in Pennsylvania is projected to fall about 82% by 2030 — from 2.5 in 2025 to a central estimate of 0.45 (95% range 0.00–1.9). A 5-year backtest shows a typical error of ±84.4%, with 40% of held-out values landing inside the 95% band.19662030
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 →
20260.560.002.0
20270.530.002.0
20280.510.001.9
20290.480.001.9
20300.450.001.9

Purple Martin Survey Routes in Pennsylvania

Routes recording Purple Martin 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 →
Brunnerville 24120252010
Peters Mt2719761972
Leola2320251998
Sugar Grove2020252001
Teepleville1720251967
Garrett1620251966
Williamsburg1520252013
Schaefferstown 21420252008
Brunnerville1320091969
Bendersville1320241990
Mifflintown1220241967
Mt Gretna1119701966
Rector1019771970
Doubling Gap1019771966
Landisburg920252003
Harmonsburg820241966
Ravensburg819781974
Shelocta819741968
Martinsburg820251970
Clear Spring820251967
Millville720251969
Bald Eagle720252018
Mount Joy720251989
Akeley619761966
N Pine Grove620251971

Purple Martin Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonrhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.