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Species · Pennsylvania · BBS 2025 Release · 1966–2024

Blue-headed Vireo Population Trend in Pennsylvania

All statesForest birds

Blue-headed Vireo in Pennsylvania has surged: up 63× on the route-weighted index since 1968.

63×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 →
100Routes 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-headed Vireo 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-headed Vireo has surged in Pennsylvania: up 63× on the route-weighted index since 1968.

Blue-headed Vireo Population Forecast in Pennsylvania

If the recent trend holds, Blue-headed Vireo in Pennsylvania is projected to rise about 51% by 2029 — from 1.8 in 2024 to a central estimate of 2.8 (95% range 2.1–3.5). A 5-year backtest shows a typical error of ±19.7%, with 80% of held-out values landing inside the 95% band.

+51%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 →
2.8Projected 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 →
2.1–3.595% 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 →
±19.7%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-headed Vireo in Pennsylvania is projected to rise about 51% by 2029 — from 1.8 in 2024 to a central estimate of 2.8 (95% range 2.1–3.5). A 5-year backtest shows a typical error of ±19.7%, 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 →
20252.61.93.3
20262.61.93.3
20272.72.03.4
20282.72.03.4
20292.82.13.5

Blue-headed Vireo Survey Routes in Pennsylvania

Routes recording Blue-headed Vireo 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 →
Mawr Glen1520241982
Roulette1220211972
Ansonia1220242002
N Pine Grove1120241970
Ridgway1120181988
Rasselas1120221981
Lynch1020241977
Marsh Hill1020241983
Odin920241973
Sproul Sf-B920242002
Eldred820221987
English Ctr819881987
Margaret820051992
Ellenton720241982
Rothrock Sf720191993
Broad Mtn.720241993
Sproul Sf-A720242002
Munson620241979
Ryde620051995
Russell City520241968
Arnot520241993
Pocono Summit520241975
Warrens Mill520241973
Mill Run520241987
Betula420221987

Blue-headed Vireo Population Trend in Other States

alabamaconnecticutgeorgiakentuckymainemarylandmassachusettsmichiganminnesotanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiorhode-islandsouth-carolinatennesseevermontvirginiawest-virginiawisconsin

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