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

Acadian Flycatcher Population Trend in Delaware

All statesAerial insectivores

Acadian Flycatcher in Delaware has surged: up 208% on the route-weighted index since 1968.

+208%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 →
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 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 208% 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 stay roughly flat through 2029, near 3.8 (95% range 1.7–5.9). A 5-year backtest shows a typical error of ±33.5%, with 60% of held-out values landing inside the 95% band.

+0%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 →
3.8Projected 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 →
1.7–5.995% 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 →
±33.5%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 stay roughly flat through 2029, near 3.8 (95% range 1.7–5.9). A 5-year backtest shows a typical error of ±33.5%, with 60% 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 →
20253.61.55.8
20263.71.65.8
20273.71.65.8
20283.81.65.9
20293.81.75.9

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 21120172017
Millsboro720242017
Pepperbox720161998
Harrington520241966
Holleyville320041966
Pepperbox 2320242017
Blackbird220241995
Holleyville 2220242006
Georgetown220221992
Mt Pleasant120191966
Wilmington119901967
Frederica120131966
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 2026-05-22.