BirdAnalyst
Species · New Hampshire · BBS 2025 Release · 1966–2024

American Black Duck Population Trend in New Hampshire

All statesWaterfowl

American Black Duck in New Hampshire has collapsed: down 89% on the route-weighted index since 1968.

-89%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 →
23Routes 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 →
47YearsYears 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 New HampshireNotable 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 declinecomputed 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 collapsed in New Hampshire: down 89% on the route-weighted index since 1968.

American Black Duck Population Forecast in New Hampshire

If the recent trend holds, American Black Duck in New Hampshire is projected to fall about 100% by 2027 — from 0.09 in 2022 to a central estimate of 0.00 (95% range 0.00–0.52). A 5-year backtest shows a typical error of ±127.3%, with 100% of held-out values landing inside the 95% band.

-100%Change by 2027TrendPercent 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 →
0.00Projected 2027 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.5295% 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 →
±127.3%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, American Black Duck in New Hampshire is projected to fall about 100% by 2027 — from 0.09 in 2022 to a central estimate of 0.00 (95% range 0.00–0.52). A 5-year backtest shows a typical error of ±127.3%, with 100% of held-out values landing inside the 95% band.19662027
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 →
20230.000.000.52
20240.000.000.52
20250.000.000.52
20260.000.000.52
20270.000.000.52

American Black Duck Survey Routes in New Hampshire

Routes recording American Black Duck in New Hampshire.
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 →
Fitzwilliam319951966
Concord319901966
Hopkinton219901969
Lempster220221967
Milan220161967
Stratford220141969
Clarksville220041969
Glen220001976
Peterborough119871969
Brentwood119751969
Dover119921968
Epsom119951969
Strafford120191967
Canterbury119751966
Gilmantn I W120172017
Wilmot119961982
Mt Chocorua119771972
Walpole120061971
Marlow119981967
Jefferson Hl120001976
Franconia120081967
Dixvil Notch119951966
Jeffers Ntch120102010

American Black Duck Population Trend in Other States

alabamaconnecticutdelawareindianamainemarylandmassachusettsmichiganminnesotanew-jerseynew-yorknorth-carolinanorth-dakotaohiopennsylvaniarhode-islandvermontvirginiawest-virginiawisconsin

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