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

Black-billed Cuckoo Population Trend in New Hampshire

All statesGeneralists

Black-billed Cuckoo in New Hampshire has fallen sharply: down 73% on the route-weighted index since 1968.

-73%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 →
55YearsYears 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 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 →

Black-billed Cuckoo has fallen sharply in New Hampshire: down 73% on the route-weighted index since 1968.

Black-billed Cuckoo Population Forecast in New Hampshire

If the recent trend holds, Black-billed Cuckoo in New Hampshire is projected to stay roughly flat through 2029, near 0.08 (95% range 0.00–0.85). A 5-year backtest shows a typical error of ±108.5%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.08Projected 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 →
0.00–0.8595% 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 →
±108.5%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 New Hampshire is projected to stay roughly flat through 2029, near 0.08 (95% range 0.00–0.85). A 5-year backtest shows a typical error of ±108.5%, with 100% 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 →
20250.120.000.89
20260.110.000.88
20270.100.000.87
20280.090.000.86
20290.080.000.85

Black-billed Cuckoo Survey Routes in New Hampshire

Routes recording Black-billed Cuckoo 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 →
Peterborough219961967
Brentwood219971979
Dover220151967
East Kingston220182005
Fitzwilliam120211966
Hopkinton120221967
Epsom120151968
Concord120231966
Strafford120171966
Canterbury120241968
Gilmantn I W120141970
Wilmot120231978
Mt Chocorua120221966
Walpole120161970
Marlow120131966
Lempster120161977
Crawford Not119711971
Jefferson Hl120221971
Franconia119911981
Milan120001971
Stratford120141967
Dixvil Notch119831977
Clarksville119831967
Glen120221981
Jeffers Ntch119971997

Black-billed Cuckoo Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawaregeorgiaidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamissourimontananebraskanew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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