BirdAnalyst
Species · Idaho · BBS 2025 Release · 1966–2024

Evening Grosbeak Population Trend in Idaho

All statesGeneralists

Evening Grosbeak in Idaho has collapsed: down 82% on the route-weighted index since 1972.

-82%Since 1972TrendPercent 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 →
36Routes 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 →
50YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Evening Grosbeak 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 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 →

Evening Grosbeak has collapsed in Idaho: down 82% on the route-weighted index since 1972.

Evening Grosbeak Population Forecast in Idaho

If the recent trend holds, Evening Grosbeak in Idaho is projected to fall about 100% by 2029 — from 0.56 in 2024 to a central estimate of 0.00 (95% range 0.00–2.1). A 5-year backtest shows a typical error of ±102.3%, with 100% 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 →
0.00–2.195% 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 →
±102.3%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, Evening Grosbeak in Idaho is projected to fall about 100% by 2029 — from 0.56 in 2024 to a central estimate of 0.00 (95% range 0.00–2.1). A 5-year backtest shows a typical error of ±102.3%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.060.002.1
20260.030.002.1
20270.000.002.1
20280.000.002.1
20290.000.002.1

Evening Grosbeak Survey Routes in Idaho

Routes recording Evening Grosbeak 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 →
Deep Creek5019851985
Cascade2719841981
Nezperce Nf1819991992
Golden1520031997
Centerville1520021982
Coolin720241986
Mivoden620221977
N Fork Cda R620132005
Cobalt620241989
Alturas519871987
Challis320231992
Leadore320092009
Cabarton320221985
Avery220222010
Gifford219861971
Nezperce220121969
Grangeville220221987
Cape Horn220061987
Squirrel219771972
Sawtooth City 2220222022
Burgdorf220071994
Yellow Pine220111992
Blackft Res119951986
Naples120241972
Lolo Pass120191993

Evening Grosbeak Population Trend in Other States

arizonacaliforniacoloradoconnecticutmainemassachusettsmichiganminnesotamontananevadanew-hampshirenew-mexiconew-yorkoregonsouth-dakotautahvermontwashingtonwisconsinwyoming

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