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Species · Delaware · BBS 2026 Release · 1966–2025

American Black Duck Population Trend in Delaware

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American Black Duck in Delaware has surged: up 114% on the route-weighted index since 1969.

+114%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 →
10Routes 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 →
42YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable American Black Duck 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 →

American Black Duck has surged in Delaware: up 114% on the route-weighted index since 1969.

American Black Duck Population Forecast in Delaware

If the recent trend holds, American Black Duck in Delaware is projected to fall about 21% by 2022 — from 0.43 in 2017 to a central estimate of 0.34 (95% range 0.00–1.1). A 5-year backtest shows a typical error of ±101%, with 100% of held-out values landing inside the 95% band.

-21%Change by 2022TrendPercent 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 →
0.34Projected 2022 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1.195% 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 →
±101%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, American Black Duck in Delaware is projected to fall about 21% by 2022 — from 0.43 in 2017 to a central estimate of 0.34 (95% range 0.00–1.1). A 5-year backtest shows a typical error of ±101%, with 100% of held-out values landing inside the 95% band.19672022
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 →
20180.350.001.1
20190.350.001.1
20200.350.001.1
20210.340.001.1
20220.340.001.1

American Black Duck Survey Routes in Delaware

Routes recording American Black Duck 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 Bch419901967
Holleyville 2320172017
Holleyville220011971
Lowes Xrds219801972
Mt Pleasant120101968
Wilmington119961978
Harrington120161969
Frederica119721972
Dover119791972
Blackbird120091995

American Black Duck Population Trend in Other States

alabamaconnecticutindianamainemarylandmassachusettsmichiganminnesotanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiopennsylvaniarhode-islandvermontvirginiawest-virginiawisconsin

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