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Species · Idaho · BBS 2026 Release · 1966–2025

Nashville Warbler Population Trend in Idaho

All statesForest birds

Nashville Warbler in Idaho has surged: up 143% on the route-weighted index since 1977.

+143%Since 1977TrendPercent 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 →
29Routes 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 →
47YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Nashville Warbler Trends in IdahoNotable 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 increasecomputed 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 →

Nashville Warbler has surged in Idaho: up 143% on the route-weighted index since 1977.

Nashville Warbler Population Forecast in Idaho

If the recent trend holds, Nashville Warbler in Idaho is projected to rise about 85% by 2030 — from 0.29 in 2025 to a central estimate of 0.53 (95% range 0.05–1.0). A 5-year backtest shows a typical error of ±32.2%, with 100% of held-out values landing inside the 95% band.

+85%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 →
0.53Projected 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 →
0.05–1.095% 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 →
±32.2%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, Nashville Warbler in Idaho is projected to rise about 85% by 2030 — from 0.29 in 2025 to a central estimate of 0.53 (95% range 0.05–1.0). A 5-year backtest shows a typical error of ±32.2%, with 100% of held-out values landing inside the 95% band.19722030
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 →
20260.510.040.99
20270.520.040.99
20280.520.040.99
20290.520.051.00
20300.530.051.0

Nashville Warbler Survey Routes in Idaho

Routes recording Nashville Warbler in Idaho.
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 →
Lolo Pass820191992
Sunbeam819941994
Rochat Divde320231994
Naples220251972
Nezperce220121993
Grangeville219951995
Golden220161997
Coolin220251987
Cobalt220252024
Pasadena Val219911991
Mivoden120251977
Avery120231990
Gifford120091989
N Fork Cda R120051995
Cape Horn120182018
Challis120252019
Centerville120251983
Triangle120122008
Glenns Ferry119861986
Baldy Mountain120152015
Marble Creek120251988
Pierce119971995
Salmon River120241991
Burgdorf120151989
Crane Creek120052004

Nashville Warbler Population Trend in Other States

californiaconnecticutmainemarylandmassachusettsmichiganminnesotamontananew-hampshirenew-jerseynew-yorknorth-dakotaoregonpennsylvaniarhode-islandvermontvirginiawashingtonwest-virginiawisconsin

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