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Species · BCR 4 · BBS 2026 Release · 1966–2025

Townsend's Warbler In BCR 4

All regionsBCR 4Forest birds

Townsend's Warbler in BCR 4 has increased: up 43% on the route-weighted index since 1984.

+43%Since 1984TrendPercent 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 →
39Routes 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 →
43YearsYears 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 Townsend's Warbler in BCR 4. See the full index history below.

Townsend's Warbler In BCR 4 Population Forecast

If the recent trend holds, Townsend's Warbler in BCR 4 is projected to stay roughly flat through 2030, near 1.9 (95% range 0.49–3.4). A 5-year backtest shows a typical error of ±11.6%, with 100% of held-out values landing inside the 95% band.

+3%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 →
1.9Projected 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 →
0.49–3.495% 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 →
±11.6%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, Townsend's Warbler in BCR 4 is projected to stay roughly flat through 2030, near 1.9 (95% range 0.49–3.4). A 5-year backtest shows a typical error of ±11.6%, with 100% of held-out values landing inside the 95% band.19822030
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 →
20261.90.493.4
20271.90.493.4
20281.90.493.4
20291.90.493.4
20301.90.493.4

Routes In BCR 4

Routes recording Townsend's Warbler in BCR 4.
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 →
Chena Hot Spring 2ALASKA402025
HomerALASKA251982
Birch LakeALASKA82025
Anchor RiverALASKA62025
ChickenALASKA52024
Seven LakesALASKA52019
EagleALASKA42025
SlanaALASKA42022
Chena RiverALASKA41988
L SalchaALASKA32025
Murphy DomeALASKA32025
DeltaALASKA32024
Chatanika RALASKA22025
ChistochinaALASKA22024
NorthwayALASKA22023
Kenny LakeALASKA22021
KachemakALASKA22025
Caribou Mtn.ALASKA22002
CircleALASKA12024
LivengoodALASKA12021
Tower BluffsALASKA12023
Skilak LakeALASKA11985
Hatcher PassALASKA12019
Swan Lake RdALASKA12023
Lake LouiseALASKA12010

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