BirdAnalyst
Species · BCR 10 · BBS 2025 Release · 1966–2024

Black-headed Grosbeak In Northern Rockies

All regionsNorthern RockiesGeneralists

Black-headed Grosbeak in Northern Rockies has surged: up 350% on the route-weighted index since 1970.

+350%Since 1970TrendPercent 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 →
163Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 →

Black-headed Grosbeak has surged in Northern Rockies: up 350% on the route-weighted index since 1970.

Forecast

If the recent trend holds, Black-headed Grosbeak in Northern Rockies is projected to rise about 25% by 2029 — from 1.4 in 2024 to a central estimate of 1.7 (95% range 1.2–2.2). A 5-year backtest shows a typical error of ±14.6%, with 100% of held-out values landing inside the 95% band.

+25%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 →
1.7Projected 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 →
1.2–2.295% 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 →
±14.6%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-headed Grosbeak in Northern Rockies is projected to rise about 25% by 2029 — from 1.4 in 2024 to a central estimate of 1.7 (95% range 1.2–2.2). A 5-year backtest shows a typical error of ±14.6%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20251.61.22.1
20261.71.22.2
20271.71.22.2
20281.71.22.2
20291.71.22.2

Routes In Northern Rockies

Routes recording Black-headed Grosbeak in Northern Rockies.
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 →
SpartaOREGON221999
Buckskin MtnWYOMING152021
Libby DamMONTANA132015
AlpineWYOMING122024
CascadeIDAHO111984
KalispellMONTANA112024
WilsonWYOMING112024
East Glacier ParkMONTANA102024
NewbridgeOREGON102024
Black Mtn.OREGON102004
St. Mary 2MONTANA92024
Rochat DivdeIDAHO82023
ChestnutMONTANA82023
KellerWASHINGTON82007
Hebgen LakeMONTANA72024
BridgeportOREGON72022
Bald MtnWYOMING72007
FeathervilleIDAHO62024
ArleeMONTANA62024
ClintonMONTANA62024
ChewelahWASHINGTON62021
DuboisWYOMING62024
NaplesIDAHO52024
Lolo PassIDAHO52019
ChallisIDAHO52024

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