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

MacGillivray's Warbler In Northern Rockies

All regionsNorthern RockiesForest birds

MacGillivray's Warbler in Northern Rockies has risen sharply: up 55% on the route-weighted index since 1970.

+55%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 →
152Routes 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 →

MacGillivray's Warbler has risen sharply in Northern Rockies: up 55% on the route-weighted index since 1970.

Forecast

If the recent trend holds, MacGillivray's Warbler in Northern Rockies is projected to rise about 57% by 2029 — from 3.0 in 2024 to a central estimate of 4.7 (95% range 3.0–6.3). A 5-year backtest shows a typical error of ±57.3%, with 20% of held-out values landing inside the 95% band.

+57%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 →
4.7Projected 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 →
3.0–6.395% 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 →
±57.3%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, MacGillivray's Warbler in Northern Rockies is projected to rise about 57% by 2029 — from 3.0 in 2024 to a central estimate of 4.7 (95% range 3.0–6.3). A 5-year backtest shows a typical error of ±57.3%, with 20% 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 →
20254.52.96.2
20264.62.96.3
20274.62.96.3
20284.62.96.3
20294.73.06.3

Routes In Northern Rockies

Routes recording MacGillivray's Warbler 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 →
GoldenIDAHO472016
AlpineWYOMING292024
PierceIDAHO272007
Lolo PassIDAHO252019
Fish CreekMONTANA242024
Deep CreekIDAHO221985
MivodenIDAHO192023
SkalkahoMONTANA191998
Logan PassMONTANA182024
Black Mtn.OREGON182004
CentervilleIDAHO162019
Baldy MountainIDAHO152016
N Fork Cda RIDAHO152019
Whitefish LakeMONTANA152024
Nezperce NfIDAHO141999
CabartonIDAHO142023
LogdellOREGON142024
Donelly 2OREGON142024
ClintonMONTANA132024
NezperceIDAHO122012
NoxonMONTANA122023
Summit PrOREGON122024
DesolationOREGON122007
LaurierWASHINGTON122022
Colter BayWYOMING121998

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