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Species · Utah · BBS 2026 Release · 1966–2025

MacGillivray's Warbler Population Trend in Utah

All statesForest birds

MacGillivray's Warbler in Utah has surged: up 398% on the route-weighted index since 1970.

+398%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 →
52Routes 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 →
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 MacGillivray's Warbler Trends in UtahNotable 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 surged in Utah: up 398% on the route-weighted index since 1970.

MacGillivray's Warbler Population Forecast in Utah

If the recent trend holds, MacGillivray's Warbler in Utah is projected to stay roughly flat through 2030, near 1.6 (95% range 0.00–3.6). A 5-year backtest shows a typical error of ±64.1%, with 100% of held-out values landing inside the 95% band.

+6%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 →
1.6Projected 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 →
0.00–3.695% 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 →
±64.1%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 Utah is projected to stay roughly flat through 2030, near 1.6 (95% range 0.00–3.6). A 5-year backtest shows a typical error of ±64.1%, with 100% 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 →
20261.50.003.5
20271.50.003.5
20281.50.003.5
20291.50.003.6
20301.60.003.6

MacGillivray's Warbler Survey Routes in Utah

Routes recording MacGillivray's Warbler in Utah.
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 →
Lost Cr. Res3220181995
Beck 22120251990
Heber Mtn.1220251996
Uintah Nf1019941987
Book Ridge920062003
Woodruff920252003
Beck819871968
Beaver720251979
Gooseberry720251994
Soapstone620251992
La Sal 3620252007
Skyline Driv520251986
Main Canyon520252005
Moon Lake 2420232004
Grizzly Rdge420251997
La Sal 2420062004
Logan Canyon420191998
Hill Creek419951994
Richfield420191994
Ferron420252000
Monticello420251998
Hardware Ranch420231994
Hyrum319781975
Navajo Lake320251987
Randolph320251995

MacGillivray's Warbler Population Trend in Other States

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