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Species · Delaware · BBS 2026 Release · 1966–2025

Eastern Bluebird Population Trend in Delaware

All statesForest birds

Eastern Bluebird in Delaware has surged: up 18× on the route-weighted index since 1969.

18×Since 1969TrendPercent 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 →
15Routes 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 →
54YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Eastern Bluebird 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 →

Eastern Bluebird has surged in Delaware: up 18× on the route-weighted index since 1969.

Eastern Bluebird Population Forecast in Delaware

If the recent trend holds, Eastern Bluebird in Delaware is projected to rise about 155% by 2030 — from 3.0 in 2025 to a central estimate of 7.6 (95% range 4.8–11). A 5-year backtest shows a typical error of ±50.3%, with 20% of held-out values landing inside the 95% band.

+155%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 →
7.6Projected 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 →
4.8–1195% 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 →
±50.3%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, Eastern Bluebird in Delaware is projected to rise about 155% by 2030 — from 3.0 in 2025 to a central estimate of 7.6 (95% range 4.8–11). A 5-year backtest shows a typical error of ±50.3%, with 20% 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 →
20267.14.210
20277.24.310
20287.44.510
20297.54.610
20307.64.811

Eastern Bluebird Survey Routes in Delaware

Routes recording Eastern Bluebird 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 →
Georgetown1520221992
Holleyville 21020242006
Mt Pleasant920191969
Holleyville920041966
Frankford820121968
Wilmington420141991
Harrington420251973
Blackbird420251994
Pepperbox 2420252017
Pepperbox320161998
Milton 2320252017
Millsboro220252017
Frederica120251966
Lowes Xrds119851966
Milton120161994

Eastern Bluebird Population Trend in Other States

alabamaarizonaarkansascoloradoconnecticutfloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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