BirdAnalyst
Species · Pennsylvania · BBS 2025 Release · 1966–2024

Least Flycatcher Population Trend in Pennsylvania

All statesAerial insectivores

Least Flycatcher in Pennsylvania has declined: down 41% on the route-weighted index since 1968.

-41%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 →
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 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 rise about 15% by 2029 — from 1.1 in 2024 to a central estimate of 1.2 (95% range 0.15–2.3). A 5-year backtest shows a typical error of ±74.9%, with 100% of held-out values landing inside the 95% band.

+15%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 →
1.2Projected 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 →
0.15–2.395% 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 →
±74.9%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 rise about 15% by 2029 — from 1.1 in 2024 to a central estimate of 1.2 (95% range 0.15–2.3). A 5-year backtest shows a typical error of ±74.9%, with 100% 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 →
20251.30.242.4
20261.30.222.4
20271.30.202.4
20281.30.172.3
20291.20.152.3

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 →
Poyntelle1120241973
Ralston919661966
Starlight819991970
English Ctr719891966
Ltl Pine Cr720241990
Mawr Glen620241982
Roulette 2620242022
Eldred520221974
Arnot520241969
West Grove519921969
Broad Mtn.520241994
Akeley419791966
Odin420241973
Logue420231976
Austinville420241966
Honesdale420241972
Canadensis420241971
Munson420241982
Sugar Grove420231980
Ellenton420241982
Ansonia420242002
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 2026-05-22.