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

Brown Thrasher Population Trend in New Hampshire

All statesGeneralists

Brown Thrasher in New Hampshire has collapsed: down 91% on the route-weighted index since 1968.

-91%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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Brown Thrasher 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 →

Brown Thrasher has collapsed in New Hampshire: down 90% on the route-weighted index since 1968.

Brown Thrasher Population Forecast in New Hampshire

If the recent trend holds, Brown Thrasher in New Hampshire is projected to fall about 100% by 2029 — from 0.09 in 2024 to a central estimate of 0.00 (95% range 0.00–1.2). A 5-year backtest shows a typical error of ±957.2%, with 60% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–1.295% 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 →
±957.2%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, Brown Thrasher in New Hampshire is projected to fall about 100% by 2029 — from 0.09 in 2024 to a central estimate of 0.00 (95% range 0.00–1.2). A 5-year backtest shows a typical error of ±957.2%, with 60% 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 →
20250.000.001.2
20260.000.001.2
20270.000.001.2
20280.000.001.2
20290.000.001.2

Brown Thrasher Survey Routes in New Hampshire

Routes recording Brown Thrasher 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 →
Jefferson Hl320221967
East Kingston220002000
Peterborough119911966
Brentwood119981966
Fitzwilliam120181966
Dover120141966
Hopkinton119931966
Epsom120041966
Concord120191966
Strafford119821966
Canterbury120231966
Gilmantn I W120191969
Wilmot119941966
Mt Chocorua120221966
Walpole119891966
Marlow120221968
Lempster120241966
Crawford Not119731969
Franconia120011966
Milan120241966
Stratford120231966
Dixvil Notch120151970
Clarksville120161967
Glen120221975
Jeffers Ntch119991999

Brown Thrasher Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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