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Species · Delaware · BBS 2025 Release · 1966–2024

Great Crested Flycatcher Population Trend in Delaware

All statesAerial insectivores

Great Crested Flycatcher in Delaware has surged: up 170% on the route-weighted index since 1968.

+170%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 →
17Routes 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 Great Crested Flycatcher Trends in DelawareNotable 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 →

Great Crested Flycatcher has surged in Delaware: up 170% on the route-weighted index since 1968.

Great Crested Flycatcher Population Forecast in Delaware

If the recent trend holds, Great Crested Flycatcher in Delaware is projected to fall about 15% by 2029 — from 11 in 2024 to a central estimate of 9.7 (95% range 6.1–13). A 5-year backtest shows a typical error of ±25.3%, with 80% 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 →
9.7Projected 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 →
6.1–1395% 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 →
±25.3%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, Great Crested Flycatcher in Delaware is projected to fall about 15% by 2029 — from 11 in 2024 to a central estimate of 9.7 (95% range 6.1–13). A 5-year backtest shows a typical error of ±25.3%, with 80% 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 →
20259.15.613
20269.35.713
20279.45.913
20289.56.013
20299.76.113

Great Crested Flycatcher Survey Routes in Delaware

Routes recording Great Crested Flycatcher in Delaware.
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 →
Harrington2820241966
Pepperbox1620161998
Milton 21620172017
Pepperbox 21220242017
Frederica820141966
Millsboro720242017
Holleyville 2720242006
Holleyville620041966
Milton620161966
Mt Pleasant420191966
Frankford420121966
Lowes Xrds419911966
Wilmington320141967
Blackbird320241994
Georgetown320221992
Dover219871966
Bethany Bch119901966

Great Crested Flycatcher Population Trend in Other States

alabamaarkansascoloradoconnecticutfloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsin

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