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Species · Pennsylvania · BBS 2025 Release · 1966–2024

Scarlet Tanager Population Trend in Pennsylvania

All statesGeneralists

Scarlet Tanager in Pennsylvania has risen sharply: up 65% on the route-weighted index since 1968.

+65%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 →
134Routes 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 Scarlet Tanager 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 →

Scarlet Tanager has risen sharply in Pennsylvania: up 65% on the route-weighted index since 1968.

Scarlet Tanager Population Forecast in Pennsylvania

If the recent trend holds, Scarlet Tanager in Pennsylvania is projected to rise about 29% by 2029 — from 6.9 in 2024 to a central estimate of 8.9 (95% range 6.3–11). A 5-year backtest shows a typical error of ±34.4%, with 40% of held-out values landing inside the 95% band.

+29%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 →
8.9Projected 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 →
6.3–1195% 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 →
±34.4%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, Scarlet Tanager in Pennsylvania is projected to rise about 29% by 2029 — from 6.9 in 2024 to a central estimate of 8.9 (95% range 6.3–11). A 5-year backtest shows a typical error of ±34.4%, with 40% 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 →
20258.76.111
20268.76.111
20278.86.211
20288.86.211
20298.96.311

Scarlet Tanager Survey Routes in Pennsylvania

Routes recording Scarlet Tanager 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.5120241993
Duboistown2020241987
Ryde1820051968
Mill Run1820241978
Sigel1720241981
Stoneybreak1720241992
Laurel Hill1620241978
Wild Creek1620241988
Rothrock Sf1620191992
St College1520241969
Broad Mtn.1520241993
Mawr Glen1420241966
Waller1420241971
Munson1420241979
Sproul Sf-B1420242002
Greentown1320241969
Canadensis1320241969
Ramsey1220231968
Odin1120241973
Warrens Mill1120241971
Roulette1020211970
Rosecrans1020241969
Rector1019771966
Martinsburg1020241970
Williamsburg1020241988

Scarlet Tanager Population Trend in Other States

alabamaarkansasconnecticutdelawaregeorgiaillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomarhode-islandsouth-carolinatennesseevermontvirginiawest-virginiawisconsin

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