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

Barn Swallow Population Trend in Delaware

All statesAerial insectivores

Barn Swallow in Delaware has surged: up 96% on the route-weighted index since 1968.

+96%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 Barn Swallow 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 →

Barn Swallow has surged in Delaware: up 96% on the route-weighted index since 1968.

Barn Swallow Population Forecast in Delaware

If the recent trend holds, Barn Swallow in Delaware is projected to fall about 12% by 2029 — from 37 in 2024 to a central estimate of 33 (95% range 23–42). A 5-year backtest shows a typical error of ±18.2%, with 100% of held-out values landing inside the 95% band.

-12%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 →
33Projected 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 →
23–4295% 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 →
±18.2%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, Barn Swallow in Delaware is projected to fall about 12% by 2029 — from 37 in 2024 to a central estimate of 33 (95% range 23–42). A 5-year backtest shows a typical error of ±18.2%, with 100% 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 →
2025322241
2026322241
2027322342
2028322342
2029332342

Barn Swallow Survey Routes in Delaware

Routes recording Barn Swallow 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 →
Harrington6220241966
Bethany Bch4419901966
Blackbird4420241994
Frederica4320141966
Dover3819871966
Frankford3720121966
Millsboro3220242017
Holleyville 23120242006
Holleyville2720041966
Milton2620161966
Milton 21920172017
Lowes Xrds1619911966
Pepperbox 21620242017
Mt Pleasant1520191966
Pepperbox1220161998
Georgetown1120221992
Wilmington320141966

Barn Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutfloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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