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

Purple Martin Population Trend in Delaware

All statesAerial insectivores

Purple Martin in Delaware has surged: up 962% on the route-weighted index since 1968.

+962%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 Purple Martin 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 →

Purple Martin has surged in Delaware: up 962% on the route-weighted index since 1968.

Purple Martin Population Forecast in Delaware

If the recent trend holds, Purple Martin in Delaware is projected to fall about 16% by 2029 — from 57 in 2024 to a central estimate of 48 (95% range 37–59). A 5-year backtest shows a typical error of ±20.1%, with 60% of held-out values landing inside the 95% band.

-16%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 →
48Projected 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 →
37–5995% 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 →
±20.1%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, Purple Martin in Delaware is projected to fall about 16% by 2029 — from 57 in 2024 to a central estimate of 48 (95% range 37–59). A 5-year backtest shows a typical error of ±20.1%, 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 →
2025453456
2026463556
2027473657
2028473758
2029483759

Purple Martin Survey Routes in Delaware

Routes recording Purple Martin 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 →
Harrington11820241967
Blackbird9120241994
Frederica8820141966
Milton 25920172017
Georgetown4620221992
Pepperbox3620161998
Millsboro3320242017
Frankford2620121966
Milton2620161966
Holleyville 22620242006
Bethany Bch2419901966
Dover2219871966
Holleyville1820041968
Pepperbox 21820242017
Lowes Xrds519911966
Mt Pleasant320161966
Wilmington220131966

Purple Martin Population Trend in Other States

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

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