BirdAnalyst
Species · BCR 15 · BBS 2026 Release · 1966–2025

MacGillivray's Warbler In Sierra Nevada

All regionsSierra NevadaForest birds

MacGillivray's Warbler in Sierra Nevada has held roughly steady: down 4% on the route-weighted index since 1972.

-4%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 RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
55YearsYears 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 →

No notable trend signals for MacGillivray's Warbler in Sierra Nevada. See the full index history below.

MacGillivray's Warbler In Sierra Nevada Population Forecast

If the recent trend holds, MacGillivray's Warbler in Sierra Nevada is projected to stay roughly flat through 2030, near 4.8 (95% range 2.8–6.8). A 5-year backtest shows a typical error of ±42.6%, with 60% of held-out values landing inside the 95% band.

+2%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 →
4.8Projected 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 →
2.8–6.895% 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 →
±42.6%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, MacGillivray's Warbler in Sierra Nevada is projected to stay roughly flat through 2030, near 4.8 (95% range 2.8–6.8). A 5-year backtest shows a typical error of ±42.6%, with 60% of held-out values landing inside the 95% band.19682030
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 →
20264.62.66.6
20274.72.76.7
20284.72.76.7
20294.72.76.7
20304.82.86.8

Routes In Sierra Nevada

Routes recording MacGillivray's Warbler in Sierra Nevada.
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 →
Cottage SpgsCALIFORNIA171975
Tuolumne GroveCALIFORNIA162025
RivertonCALIFORNIA142025
JohnsvilleCALIFORNIA112025
LakeshoreCALIFORNIA112024
DardanelleCALIFORNIA92019
WoodfordsCALIFORNIA92025
StrawberryCALIFORNIA92019
DownievilleCALIFORNIA82025
Greenhorn MtCALIFORNIA62008
Butte MeadowCALIFORNIA62014
ChesterCALIFORNIA52017
Little TruckeeCALIFORNIA52025
Pollock PinesCALIFORNIA52025
WestvilleCALIFORNIA42025
Last ChanceCALIFORNIA42019
Silver CityCALIFORNIA32013
Higgins CornCALIFORNIA31982
Tahoe NfCALIFORNIA31994
Meadow ValleyCALIFORNIA32025
WawonaCALIFORNIA32025
Forest Hill 2CALIFORNIA32005
LumberyardCALIFORNIA22025
PlacervilleCALIFORNIA22025
Pine MountainCALIFORNIA22017

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