BirdAnalyst
Species · New Jersey · BBS 2025 Release · 1966–2024

Willow Flycatcher Population Trend in New Jersey

All statesAerial insectivores

Willow Flycatcher in New Jersey has surged: up 78% on the route-weighted index since 1970.

+78%Since 1970TrendPercent 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 →
28Routes 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 →
56YearsYears 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 New JerseyNotable 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 New Jersey: up 78% on the route-weighted index since 1970.

Willow Flycatcher Population Forecast in New Jersey

If the recent trend holds, Willow Flycatcher in New Jersey is projected to rise about 46% by 2029 — from 0.48 in 2024 to a central estimate of 0.69 (95% range 0.21–1.2). A 5-year backtest shows a typical error of ±55.1%, with 100% of held-out values landing inside the 95% band.

+46%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 →
0.69Projected 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 →
0.21–1.295% 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 →
±55.1%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, Willow Flycatcher in New Jersey is projected to rise about 46% by 2029 — from 0.48 in 2024 to a central estimate of 0.69 (95% range 0.21–1.2). A 5-year backtest shows a typical error of ±55.1%, 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 →
20250.680.191.2
20260.680.201.2
20270.680.201.2
20280.690.211.2
20290.690.211.2

Willow Flycatcher Survey Routes in New Jersey

Routes recording Willow Flycatcher in New Jersey.
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 →
Croton320071970
Hope319941974
Gillette320241988
Ramseysburg320241995
Sandbrook220221969
Bloomsbury220231969
Dover220231984
Ocean City220242014
Croton 2220232010
Woodbury Hgt119951986
Deepwater119711971
Toms River119661966
Masonville119661966
Holmansville120041992
Clarksville119721972
New Bedford120241995
Robbinsville119781969
Midvale120161995
Kemah Lake120241983
High Point120221986
Pottersville120181981
Keyport120151990
Cranbury120151987
Roosevelt120131986
Friendship120182018

Willow Flycatcher Population Trend in Other States

alaskaarizonaarkansascaliforniacoloradoconnecticutdelawaregeorgiaidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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