BirdAnalyst
Species · Pennsylvania · BBS 2025 Release · 1966–2024

Eastern Bluebird Population Trend in Pennsylvania

All statesForest birds

Eastern Bluebird in Pennsylvania has surged: up 263% on the route-weighted index since 1968.

+263%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 →
135Routes 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 Eastern Bluebird 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 →

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 →

Eastern Bluebird has surged in Pennsylvania: up 263% on the route-weighted index since 1968.

Eastern Bluebird Population Forecast in Pennsylvania

If the recent trend holds, Eastern Bluebird in Pennsylvania is projected to rise about 11% by 2029 — from 4.6 in 2024 to a central estimate of 5.1 (95% range 3.8–6.4). A 5-year backtest shows a typical error of ±21.2%, with 80% of held-out values landing inside the 95% band.

+11%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 →
5.1Projected 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 →
3.8–6.495% 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 →
±21.2%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, Eastern Bluebird in Pennsylvania is projected to rise about 11% by 2029 — from 4.6 in 2024 to a central estimate of 5.1 (95% range 3.8–6.4). A 5-year backtest shows a typical error of ±21.2%, 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 →
20254.93.66.2
20264.93.66.2
20275.03.76.3
20285.13.86.4
20295.13.86.4

Eastern Bluebird Survey Routes in Pennsylvania

Routes recording Eastern Bluebird 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 →
Ryde2320051970
Middletown1520241984
Williamsburg1420241988
Naginey1420241970
Jefferson1420241966
Brick Tavern1420241990
Espyville1320241989
Clover1220241981
Needmore1219911966
Wyalusing1220241985
Harmonsburg1120231966
Doe Run1120241975
Berwick1120241985
Jeannette1020231981
Mount Joy1020241990
Hop Bottom920241968
Greentown920241969
Drehersville 2920242000
Doylesburg820232009
Stoneybreak820241992
Jacobus820241987
Waller720241977
Millville720241970
Bald Eagle720241978
Clear Spring720241985

Eastern Bluebird Population Trend in Other States

alabamaarizonaarkansascoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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