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

Acadian Flycatcher Population Trend in Delaware

All statesAerial insectivores

Acadian Flycatcher in Delaware has surged: up 217% on the route-weighted index since 1968.

+217%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 →
16Routes 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 Acadian 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 →

Acadian Flycatcher has surged in Delaware: up 217% on the route-weighted index since 1968.

Acadian Flycatcher Population Forecast in Delaware

If the recent trend holds, Acadian Flycatcher in Delaware is projected to fall about 34% by 2030 — from 6.0 in 2025 to a central estimate of 4.0 (95% range 1.9–6.1). A 5-year backtest shows a typical error of ±40.5%, with 40% of held-out values landing inside the 95% band.

-34%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 →
4.0Projected 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 →
1.9–6.195% 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 →
±40.5%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, Acadian Flycatcher in Delaware is projected to fall about 34% by 2030 — from 6.0 in 2025 to a central estimate of 4.0 (95% range 1.9–6.1). A 5-year backtest shows a typical error of ±40.5%, with 40% 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 →
20263.81.75.9
20273.81.85.9
20283.91.86.0
20293.91.86.0
20304.01.96.1

Acadian Flycatcher Survey Routes in Delaware

Routes recording Acadian 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 →
Milton 21020252017
Harrington920251966
Pepperbox720161998
Frederica520251966
Millsboro520252017
Pepperbox 2520252017
Holleyville320041966
Blackbird220251995
Holleyville 2220242006
Georgetown220221992
Mt Pleasant120191966
Wilmington119901967
Dover119751972
Frankford120121966
Lowes Xrds119911966
Milton120161966

Acadian Flycatcher Population Trend in Other States

alabamaarkansasconnecticutfloridageorgiaillinoisindianaiowakansaskentuckylouisianamarylandmassachusettsmichiganminnesotamississippimissourinew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseetexasvirginiawest-virginiawisconsin

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