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

Eastern Bluebird Population Trend in Delaware

All statesForest birds

Eastern Bluebird in Delaware has surged: up 24× on the route-weighted index since 1969.

24×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 →
53YearsYears 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 24× 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 fall about 23% by 2029 — from 10 in 2024 to a central estimate of 7.8 (95% range 5.1–11). A 5-year backtest shows a typical error of ±31.8%, with 40% of held-out values landing inside the 95% band.

-23%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 →
7.8Projected 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 →
5.1–1195% 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 →
±31.8%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 fall about 23% by 2029 — from 10 in 2024 to a central estimate of 7.8 (95% range 5.1–11). A 5-year backtest shows a typical error of ±31.8%, with 40% 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 →
20257.34.69.9
20267.44.710
20277.54.910
20287.75.010
20297.85.111

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 →
Frederica1520141966
Georgetown1520221992
Millsboro1420242017
Harrington1020241973
Holleyville 21020242006
Pepperbox 21020242017
Mt Pleasant920191969
Holleyville920041966
Frankford820121968
Blackbird720241994
Milton 2720172017
Wilmington420141991
Pepperbox320161998
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 2026-05-22.