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

Willow Flycatcher Population Trend in Maryland

All statesAerial insectivores

Willow Flycatcher in Maryland has surged: up 239% on the route-weighted index since 1968.

+239%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 →
44Routes 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 Willow Flycatcher Trends in MarylandNotable 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 →

Willow Flycatcher has surged in Maryland: up 239% on the route-weighted index since 1968.

Willow Flycatcher Population Forecast in Maryland

If the recent trend holds, Willow Flycatcher in Maryland is projected to rise about 113% by 2029 — from 0.45 in 2024 to a central estimate of 0.96 (95% range 0.30–1.6). A 5-year backtest shows a typical error of ±154.9%, with 20% of held-out values landing inside the 95% band.

+113%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 →
0.96Projected 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 →
0.30–1.695% 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 →
±154.9%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, Willow Flycatcher in Maryland is projected to rise about 113% by 2029 — from 0.45 in 2024 to a central estimate of 0.96 (95% range 0.30–1.6). A 5-year backtest shows a typical error of ±154.9%, with 20% 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 →
20250.930.271.6
20260.940.281.6
20270.950.281.6
20280.950.291.6
20290.960.301.6

Willow Flycatcher Survey Routes in Maryland

Routes recording Willow Flycatcher in Maryland.
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 →
Emmitsburg520241971
Mt Nebo419891973
Warfieldsbrg320181967
Eklo320181967
Floyd220231973
Vindex220211974
Williamsport220241975
Olney220241966
Pleasant Val220241970
Randallstown220131966
Cheltenham220031982
Madonna220192009
Honga220032003
Finzel220241996
Fair Hill219951993
Oldtown119731973
Potomac Park120241973
Smithsburg120141972
Wolfsville120241966
Silver Spg119881981
Bald Friar119961994
Bachman Mill120241971
Fowblesburg120161967
Upper Xrds120071970
Van Bibber120041973

Willow Flycatcher Population Trend in Other States

alaskaarizonaarkansascaliforniacoloradoconnecticutdelawaregeorgiaidahoillinoisindianaiowakansaskentuckymainemassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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