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Species · Maryland · BBS 2025 Release · 1966–2024

American Black Duck Population Trend in Maryland

All statesWaterfowl

American Black Duck in Maryland has declined: down 48% on the route-weighted index since 1968.

-48%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 →
22Routes 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 →
56YearsYears 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 MarylandNotable 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 Maryland. See the full index history below.

American Black Duck Population Forecast in Maryland

If the recent trend holds, American Black Duck in Maryland is projected to fall about 63% by 2029 — from 0.12 in 2024 to a central estimate of 0.04 (95% range 0.00–0.30). A 5-year backtest shows a typical error of ±70%, with 80% of held-out values landing inside the 95% band.

-63%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 →
0.04Projected 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 →
0.00–0.3095% 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 →
±70%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 Maryland is projected to fall about 63% by 2029 — from 0.12 in 2024 to a central estimate of 0.04 (95% range 0.00–0.30). A 5-year backtest shows a typical error of ±70%, with 80% 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 →
20250.060.000.31
20260.060.000.31
20270.050.000.30
20280.050.000.30
20290.040.000.30

American Black Duck Survey Routes in Maryland

Routes recording American Black Duck in Maryland.
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 →
Theodore1119741974
Emmitsburg819711971
Jones519721972
Madison420241966
Millington319801968
Melitota319711968
Easton319981998
Sinepuxent319761973
Silver Spg219681967
Tall Timbers219921972
Newark220031980
Forest Grove220122012
Olney119891989
Indiantown119891989
Northeast119691969
Elkton119941967
Piney Neck119981972
Harmony119821982
Golden Hill119801974
Honga120241966
Mardela119801972
Cokesbury120232003

American Black Duck Population Trend in Other States

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

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