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Species · Pennsylvania · BBS 2025 Release · 1966–2024

Blue-gray Gnatcatcher Population Trend in Pennsylvania

All statesForest birds

Blue-gray Gnatcatcher in Pennsylvania has surged: up 204% on the route-weighted index since 1968.

+204%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 →
124Routes 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 Blue-gray Gnatcatcher 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 →

Blue-gray Gnatcatcher has surged in Pennsylvania: up 204% on the route-weighted index since 1968.

Blue-gray Gnatcatcher Population Forecast in Pennsylvania

If the recent trend holds, Blue-gray Gnatcatcher in Pennsylvania is projected to rise about 21% by 2029 — from 1.3 in 2024 to a central estimate of 1.6 (95% range 0.87–2.3). A 5-year backtest shows a typical error of ±39.1%, with 80% of held-out values landing inside the 95% band.

+21%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 →
1.6Projected 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 →
0.87–2.395% 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 →
±39.1%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, Blue-gray Gnatcatcher in Pennsylvania is projected to rise about 21% by 2029 — from 1.3 in 2024 to a central estimate of 1.6 (95% range 0.87–2.3). A 5-year backtest shows a typical error of ±39.1%, 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 →
20251.50.812.2
20261.50.832.2
20271.50.842.2
20281.50.852.2
20291.60.872.3

Blue-gray Gnatcatcher Survey Routes in Pennsylvania

Routes recording Blue-gray Gnatcatcher 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 →
Tussey Mtn.1120241993
Canadensis1020241985
Ryde1020051978
Mt Gretna 2720172014
Stoneybreak720241992
South Mtn720231986
Sardis519741970
Geeseytown520241987
Peru Mills520241966
New Ringgold520241974
N Washington420241967
Eldred420151987
Pine Gr Mill420241971
Mifflintown420231989
Doe Run420231971
Berwick420241985
Bald Eagle320241977
Scheafferstn320011999
Landisburg320241978
Chatham320242000
Wild Creek320241988
Broad Mtn.320241993
Espyville220171994
Ferris Crnrs220241975
Whig Hill220241970

Blue-gray Gnatcatcher Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinaohiooklahomaoregonrhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawest-virginiawisconsinwyoming

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