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Species · Pennsylvania · BBS 2026 Release · 1966–2025

Common Grackle Population Trend in Pennsylvania

All statesGeneralists

Common Grackle in Pennsylvania has collapsed: down 75% on the route-weighted index since 1968.

-75%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 →
136Routes 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 Common Grackle 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 declinecomputed 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 →

Common Grackle has collapsed in Pennsylvania: down 75% on the route-weighted index since 1968.

Common Grackle Population Forecast in Pennsylvania

If the recent trend holds, Common Grackle in Pennsylvania is projected to fall about 44% by 2030 — from 26 in 2025 to a central estimate of 15 (95% range 0.00–37). A 5-year backtest shows a typical error of ±22.1%, with 100% of held-out values landing inside the 95% band.

-44%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 →
15Projected 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 →
0.00–3795% 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 →
±22.1%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, Common Grackle in Pennsylvania is projected to fall about 44% by 2030 — from 26 in 2025 to a central estimate of 15 (95% range 0.00–37). A 5-year backtest shows a typical error of ±22.1%, with 100% 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 →
2026200.0042
2027190.0041
2028170.0040
2029160.0038
2030150.0037

Common Grackle Survey Routes in Pennsylvania

Routes recording Common Grackle 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 →
Akron40419971989
Scheafferstn30120011966
Sporting Hil22919771977
Aspers19119891968
Brunnerville18820091969
Pottstown18319871966
Leola15920251998
Mt Gretna15820001966
Schaefferstown 215620252002
Labott15019831966
Rector14319771966
Doylesburg13320232009
Gatchelville13219901972
Big Flat12619811966
Ephrata12119881969
Carsonville12020231966
Williamsburg11720251988
Drehersville11719991966
Ryde11220051968
Drehersville 210420252000
West Grove10019961966
Slippery Rk9619941970
Peters Mt9619941972
Ramsey9320251968
Mt Gretna 28720222001

Common Grackle Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawest-virginiawisconsinwyoming

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