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Species · Delaware · BBS 2025 Release · 1966–2024

American Black Duck Population Trend in Delaware

All statesWaterfowl

American Black Duck in Delaware has increased: up 45% on the route-weighted index since 1969.

+45%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 →
9Routes 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 →
41YearsYears 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 →

No notable trend signals for American Black Duck in Delaware. See the full index history below.

American Black Duck Population Forecast in Delaware

If the recent trend holds, American Black Duck in Delaware is projected to rise about 101% by 2021 — from 0.17 in 2016 to a central estimate of 0.34 (95% range 0.00–1.1). A 5-year backtest shows a typical error of ±121.6%, with 100% of held-out values landing inside the 95% band.

+101%Change by 2021TrendPercent 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 2021 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 →
±121.6%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 rise about 101% by 2021 — from 0.17 in 2016 to a central estimate of 0.34 (95% range 0.00–1.1). A 5-year backtest shows a typical error of ±121.6%, with 100% of held-out values landing inside the 95% band.19672021
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 →
20170.350.001.1
20180.350.001.1
20190.340.001.1
20200.340.001.1
20210.340.001.1

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
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 2026-05-22.