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Species · Pennsylvania · BBS 2025 Release · 1966–2024

Common Grackle Population Trend in Pennsylvania

All statesGeneralists

Common Grackle in Pennsylvania has fallen sharply: 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 →
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 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 fallen sharply 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 41% by 2029 — from 27 in 2024 to a central estimate of 16 (95% range 0.00–38). A 5-year backtest shows a typical error of ±24.3%, with 100% of held-out values landing inside the 95% band.

-41%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 →
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 →
0.00–3895% 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 →
±24.3%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 41% by 2029 — from 27 in 2024 to a central estimate of 16 (95% range 0.00–38). A 5-year backtest shows a typical error of ±24.3%, with 100% 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 →
2025210.0043
2026200.0042
2027180.0041
2028170.0039
2029160.0038

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
Mt Gretna15820001966
Labott15019831966
Rector14319771966
Leola14120241998
Doylesburg13320232009
Gatchelville13219901972
Big Flat12619811966
Drehersville 212320242000
Ephrata12119881969
Carsonville12020231966
Drehersville11719991966
Ryde11220051968
Williamsburg11120241988
Brunnerville 210920242010
Schaefferstown 210520242002
West Grove10019961966
Slippery Rk9619941970
Peters Mt9619941972
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 2026-05-22.