BirdAnalyst
Species · New Hampshire · BBS 2026 Release · 1966–2025

Canada Warbler Population Trend in New Hampshire

All statesForest birds

Canada Warbler in New Hampshire has collapsed: down 86% on the route-weighted index since 1968.

-86%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 →
26Routes 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 →
59YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Canada Warbler 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 →

Canada Warbler has collapsed in New Hampshire: down 86% on the route-weighted index since 1968.

Canada Warbler Population Forecast in New Hampshire

If the recent trend holds, Canada Warbler in New Hampshire is projected to fall about 100% by 2030 — from 0.30 in 2025 to a central estimate of 0.00 (95% range 0.00–0.91). A 5-year backtest shows a typical error of ±173.7%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–0.9195% 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 →
±173.7%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, Canada Warbler in New Hampshire is projected to fall about 100% by 2030 — from 0.30 in 2025 to a central estimate of 0.00 (95% range 0.00–0.91). A 5-year backtest shows a typical error of ±173.7%, 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 →
20260.000.000.91
20270.000.000.91
20280.000.000.91
20290.000.000.91
20300.000.000.91

Canada Warbler Survey Routes in New Hampshire

Routes recording Canada Warbler 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 →
Dixville Notch 2520252018
Dixvil Notch320171966
Epsom220081966
Milan220151966
Clarksville220231966
Glen219971975
Peterborough119851969
Brentwood119901966
Fitzwilliam120001966
Dover119801969
Hopkinton120211966
Concord120161966
Strafford120211967
Canterbury120241966
Gilmantn I W120171970
Wilmot120191966
Mt Chocorua119981967
Walpole120161966
Marlow120191966
Lempster120081972
Crawford Not119721967
Jefferson Hl120251966
Franconia120251966
Stratford120231966
East Kingston120182000

Canada Warbler Population Trend in Other States

connecticutgeorgiaindianamainemarylandmassachusettsmichiganminnesotanew-jerseynew-yorknorth-carolinaohiopennsylvaniarhode-islandtennesseevermontvirginiawest-virginiawisconsin

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