BirdAnalyst
Species · Arizona · BBS 2025 Release · 1966–2024

Hermit Thrush Population Trend in Arizona

All statesForest birds

Hermit Thrush in Arizona has surged: up 448% on the route-weighted index since 1970.

+448%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 →
23Routes 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 →
54YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Hermit Thrush Trends in ArizonaNotable 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 →

Hermit Thrush has surged in Arizona: up 448% on the route-weighted index since 1970.

Hermit Thrush Population Forecast in Arizona

If the recent trend holds, Hermit Thrush in Arizona is projected to rise about 307% by 2029 — from 0.94 in 2024 to a central estimate of 3.8 (95% range 0.95–6.7). A 5-year backtest shows a typical error of ±113.7%, with 80% of held-out values landing inside the 95% band.

+307%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 →
3.8Projected 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 →
0.95–6.795% 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 →
±113.7%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, Hermit Thrush in Arizona is projected to rise about 307% by 2029 — from 0.94 in 2024 to a central estimate of 3.8 (95% range 0.95–6.7). A 5-year backtest shows a typical error of ±113.7%, with 80% 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 →
20253.70.816.6
20263.70.846.6
20273.80.886.7
20283.80.916.7
20293.80.956.7

Hermit Thrush Survey Routes in Arizona

Routes recording Hermit Thrush in Arizona.
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 →
Tsaile3420231993
Mt. Graham3020231995
Dry Park2920241992
Aztec Peak1119781974
Alpine1120231992
Rucker920091993
Prescott520221976
Blue519911974
Mormon Lake419751968
Sprucedale420231992
Flagstaff320221988
Sawmill320141988
Williams320191999
Tonto Vill.320191992
Pinetop320141993
Carr Mtn320111986
Portal220241977
Happy Jack220241985
Dragoon119961996
Maine120091992
Forest Lakes120161992
Sunizona 2120102010
Clay Spring120032003

Hermit Thrush Population Trend in Other States

alaskacaliforniacoloradoconnecticutidahomainemarylandmassachusettsmichiganminnesotamontananevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinaohiooregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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