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

Osprey Population Trend in Delaware

All statesGeneralists

Osprey in Delaware has surged: up 800% on the route-weighted index since 1968.

+800%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 →
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 Osprey 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 →

Osprey has surged in Delaware: up 800% on the route-weighted index since 1968.

Osprey Population Forecast in Delaware

If the recent trend holds, Osprey in Delaware is projected to fall about 35% by 2029 — from 5.2 in 2024 to a central estimate of 3.4 (95% range 0.84–5.9). A 5-year backtest shows a typical error of ±59.3%, with 20% of held-out values landing inside the 95% band.

-35%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 →
3.4Projected 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 →
0.84–5.995% 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 →
±59.3%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, Osprey in Delaware is projected to fall about 35% by 2029 — from 5.2 in 2024 to a central estimate of 3.4 (95% range 0.84–5.9). A 5-year backtest shows a typical error of ±59.3%, with 20% 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 →
20253.10.595.6
20263.20.665.7
20273.20.725.8
20283.30.785.8
20293.40.845.9

Osprey Survey Routes in Delaware

Routes recording Osprey 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 →
Bethany Bch1619901966
Harrington1220241966
Pepperbox 2820242017
Blackbird620241999
Pepperbox420161998
Milton 2420172017
Wilmington220131991
Lowes Xrds219911966
Milton220161972
Mt Pleasant120102010
Frederica119991999
Frankford119731973
Holleyville120031979
Millsboro120232021
Georgetown120221994

Osprey Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutfloridageorgiaidahoillinoisindianaiowakentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinaohiooregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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