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Species · Colorado · BBS 2025 Release · 1966–2024

MacGillivray's Warbler Population Trend in Colorado

All statesForest birds

MacGillivray's Warbler in Colorado has held roughly steady: up 8% on the route-weighted index since 1970.

+8%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 →
80Routes 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 →
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 MacGillivray's Warbler Trends in ColoradoNotable 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 Colorado. See the full index history below.

MacGillivray's Warbler Population Forecast in Colorado

If the recent trend holds, MacGillivray's Warbler in Colorado is projected to stay roughly flat through 2029, near 1.6 (95% range 0.72–2.4). A 5-year backtest shows a typical error of ±16.8%, with 100% of held-out values landing inside the 95% band.

+6%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 →
1.6Projected 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 →
0.72–2.495% 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 →
±16.8%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 Colorado is projected to stay roughly flat through 2029, near 1.6 (95% range 0.72–2.4). A 5-year backtest shows a typical error of ±16.8%, 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 →
20251.50.672.4
20261.50.682.4
20271.50.692.4
20281.60.712.4
20291.60.722.4

MacGillivray's Warbler Survey Routes in Colorado

Routes recording MacGillivray's Warbler in Colorado.
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 →
Yampa1620231970
Mcphee Res.1420241998
Aspen1220241979
Dunckley Pas1120241992
Dolores Riv1020241988
Marshall Pas1020141998
Douglas Pass820241982
Wilson Creek820241992
Ragged Mtn.820191994
Heeney820192019
Baxter Pass720241994
Lost Lake620241990
Castleton620241988
Comanche Pk620241996
Owl Creek Pass620241998
Willow Peak520211988
Guanella Pas520241994
Steamboat L.520241996
South Fork520221997
Nucla520241999
Parlin420231968
Uncompahgre420241988
Lake City420031997
Blackhead Pk420211993
Thomasville420181992

MacGillivray's Warbler Population Trend in Other States

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