BirdAnalyst
Species · Pennsylvania · BBS 2026 Release · 1966–2025

Least Flycatcher Population Trend in Pennsylvania

All statesAerial insectivores

Least Flycatcher in Pennsylvania has declined: down 38% on the route-weighted index since 1968.

-38%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 →
111Routes 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 Least Flycatcher 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 →

No notable trend signals for Least Flycatcher in Pennsylvania. See the full index history below.

Least Flycatcher Population Forecast in Pennsylvania

If the recent trend holds, Least Flycatcher in Pennsylvania is projected to stay roughly flat through 2030, near 1.2 (95% range 0.12–2.3). A 5-year backtest shows a typical error of ±60.6%, with 100% of held-out values landing inside the 95% band.

-2%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 →
1.2Projected 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 →
0.12–2.395% 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 →
±60.6%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, Least Flycatcher in Pennsylvania is projected to stay roughly flat through 2030, near 1.2 (95% range 0.12–2.3). A 5-year backtest shows a typical error of ±60.6%, 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 →
20261.30.222.4
20271.30.202.3
20281.20.172.3
20291.20.142.3
20301.20.122.3

Least Flycatcher Survey Routes in Pennsylvania

Routes recording Least Flycatcher 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 →
Poyntelle1120251973
Ralston919661966
Starlight819991970
English Ctr719891966
Mawr Glen720251982
Ltl Pine Cr720251990
Logue620251976
Odin520251973
Eldred520221974
Arnot520251969
West Grove519921969
Sugar Grove520251980
Ansonia520252002
Akeley419791966
Cherry Sprs420251974
Austinville420251966
Marsh Hill420251983
Canadensis420251971
Susquehanna420251971
Roulette 2420252022
Sproul Sf-A420252002
Sproul Sf-B420242002
Betula320221974
Ridgway320181970
Roulette320211970

Least Flycatcher Population Trend in Other States

alaskaarkansascaliforniacoloradoconnecticutgeorgiaidahoillinoisindianaiowakentuckymainemarylandmassachusettsmichiganminnesotamissourimontananebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooregonrhode-islandsouth-carolinasouth-dakotatennesseeutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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