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

Black-billed Cuckoo Population Trend in Maryland

All statesGeneralists

Black-billed Cuckoo in Maryland has collapsed: down 77% on the route-weighted index since 1968.

-77%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 →
53Routes 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 →
54YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Black-billed Cuckoo 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 →

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 →

Black-billed Cuckoo has collapsed in Maryland: down 77% on the route-weighted index since 1968.

Black-billed Cuckoo Population Forecast in Maryland

If the recent trend holds, Black-billed Cuckoo in Maryland is projected to fall about 75% by 2026 — from 0.10 in 2021 to a central estimate of 0.03 (95% range 0.00–0.17). A 5-year backtest shows a typical error of ±41.2%, with 100% of held-out values landing inside the 95% band.

-75%Change by 2026TrendPercent 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 →
0.03Projected 2026 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.1795% 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 →
±41.2%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, Black-billed Cuckoo in Maryland is projected to fall about 75% by 2026 — from 0.10 in 2021 to a central estimate of 0.03 (95% range 0.00–0.17). A 5-year backtest shows a typical error of ±41.2%, with 100% of held-out values landing inside the 95% band.19662026
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 →
20220.040.000.18
20230.030.000.18
20240.030.000.18
20250.030.000.17
20260.030.000.17

Black-billed Cuckoo Survey Routes in Maryland

Routes recording Black-billed Cuckoo 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 →
Upper Xrds420041975
Wolfsville319981977
Emmitsburg319871975
Berlin319901981
Newark319811978
Mt Nebo219901983
Bachman Mill219841969
Elkton219831966
Snow Hill219681968
Finzel220212004
Piney Grove220021995
Floyd120131966
Vindex120191966
Oldtown120071972
Potomac Park120211986
Williamsport120171991
Smithsburg119871966
Silver Spg119891989
Olney119811966
Warfieldsbrg119901966
Fowblesburg120091967
Eklo119931966
Randallstown119891967
Van Bibber120001966
Walnut120042004

Black-billed Cuckoo Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawaregeorgiaidahoillinoisindianaiowakansaskentuckymainemassachusettsmichiganminnesotamissourimontananebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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