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Species · Pennsylvania · BBS 2026 Release · 1966–2025

Northern Rough-winged Swallow Population Trend in Pennsylvania

All statesAerial insectivores

Northern Rough-winged Swallow in Pennsylvania has surged: up 86% on the route-weighted index since 1968.

+86%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 →
122Routes 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 Northern Rough-winged Swallow 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 →

Northern Rough-winged Swallow has surged in Pennsylvania: up 86% on the route-weighted index since 1968.

Northern Rough-winged Swallow Population Forecast in Pennsylvania

If the recent trend holds, Northern Rough-winged Swallow in Pennsylvania is projected to stay roughly flat through 2030, near 1.1 (95% range 0.69–1.6). A 5-year backtest shows a typical error of ±15.1%, with 100% of held-out values landing inside the 95% band.

-1%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 →
1.1Projected 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 →
0.69–1.695% 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 →
±15.1%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, Northern Rough-winged Swallow in Pennsylvania is projected to stay roughly flat through 2030, near 1.1 (95% range 0.69–1.6). A 5-year backtest shows a typical error of ±15.1%, 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 →
20261.10.661.6
20271.10.671.6
20281.10.681.6
20291.10.681.6
20301.10.691.6

Northern Rough-winged Swallow Survey Routes in Pennsylvania

Routes recording Northern Rough-winged Swallow 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 →
Mount Joy2720251979
Betula820221989
Portersville819881988
Elizabethvil820241997
Mifflintown720251966
New Ringgold720241966
Russell City620071969
Pocono Summit620251994
Poyntelle620251973
Doubling Gap619761966
Brick Tavern620251994
Kaylor520221968
Rector519661966
Hometown520251966
Drehersville519991967
Doylesburg520232013
Eldred420082005
Marsh Hill420071985
Duvall420171977
Shelocta420241972
Carsonville420231966
West Grove419961970
Schaefferstown 2420252002
Berwick420251992
Starlight319791971

Northern Rough-winged Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonrhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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