BirdAnalyst
Species · Vermont · BBS 2026 Release · 1966–2025

Black-billed Cuckoo Population Trend in Vermont

All statesForest birds

Black-billed Cuckoo in Vermont has collapsed: down 87% on the route-weighted index since 1968.

-87%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 →
25Routes 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 VermontNotable 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 Vermont: down 87% on the route-weighted index since 1968.

Black-billed Cuckoo Population Forecast in Vermont

If the recent trend holds, Black-billed Cuckoo in Vermont is projected to fall about 45% by 2030 — from 0.06 in 2025 to a central estimate of 0.03 (95% range 0.00–0.54). A 5-year backtest shows a typical error of ±40.4%, with 100% of held-out values landing inside the 95% band.

-45%Change by 2030TrendPercent 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 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.5495% 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 →
±40.4%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 Vermont is projected to fall about 45% by 2030 — from 0.06 in 2025 to a central estimate of 0.03 (95% range 0.00–0.54). A 5-year backtest shows a typical error of ±40.4%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20260.070.000.58
20270.060.000.57
20280.050.000.56
20290.040.000.55
20300.030.000.54

Black-billed Cuckoo Survey Routes in Vermont

Routes recording Black-billed Cuckoo in Vermont.
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 →
S Reading219861968
Gaysville220061966
W Rutland220241966
Marlboro120161968
North Pownal120231967
Stratton119781973
Landgrove119821966
Post Mills120121966
Shaftsbury120051966
S Wallingfrd120191966
St Johnsbury120041974
East Haven120181966
Northfld Fls120251989
Middlesex120141970
East Calais120181966
Hardwick120161966
Greensboro120211968
Fletcher120211973
Waterville119691969
Hinesburg119941973
Colchester120041986
Grand Isle119951971
Newbury 2120162016
Stowe120242003
Bristol120081997

Black-billed Cuckoo Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawaregeorgiaidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamissourimontananebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-dakotatennesseetexasvirginiawest-virginiawisconsinwyoming

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