BirdAnalyst
Species · BBS 2026 Release · 1966–2025

Western Tanager Population Analysis

CardinalidaeForest birdsPiranga ludoviciana

Western Tanager has surged: up 598% on the route-weighted index since 1969.

+598%Since 1969TrendPercent 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 →
923RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
58Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the Western Tanager

The Western Tanager (Piranga ludoviciana) is a North American member of the Cardinals & Grosbeaks (Cardinalidae). In this analysis it is grouped with the forest birds.

Size
4.5–8.5 in long (12–22 cm) — a medium songbird (typical for the family)
Habitat
Woodlands and forest edges, including wooded suburbs and parks.
Diet
Insects and spiders gleaned from foliage and bark, with seeds and berries in season.
Range
Recorded on 923 Breeding Bird Survey routes across 15 states, most concentrated in the Southern Rockies / Colorado Plateau.
Family
Cardinalidae · Forest birds

Notable Western Tanager TrendsNotable 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 →

Western Tanager has surged in surveyed states: up 598% on the route-weighted index since 1969.

Western Tanager Population Forecast

If the recent trend holds, Western Tanager is projected to stay roughly flat through 2030, near 2.4 (95% range 2.0–2.9). A 5-year backtest shows a typical error of ±12.6%, 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 →
2.4Projected 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 →
2.0–2.995% 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 →
±12.6%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, Western Tanager is projected to stay roughly flat through 2030, near 2.4 (95% range 2.0–2.9). A 5-year backtest shows a typical error of ±12.6%, with 100% of held-out values landing inside the 95% band.19672030
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 →
20262.31.82.8
20272.31.92.8
20282.41.92.8
20292.41.92.8
20302.42.02.9

Where the Western Tanager Is Detected

BBS routes recording Western Tanager, sized by most recent count.

Western Tanager Population Trend by State

Western Tanager population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Alaska+178%199010
Arizona17×197038
California+85%1970199
Colorado+133%197093
Idaho+402%197160
Montana+205%197070
Nebraskainsufficient datan/a2
Nevada+245%197427
New Mexico+354%197038
Oregon+19%1970122
South Dakota+274%196917
Texas+62%20076
Utah+147%197084
Washington+90%197086
Wyoming+29%197071

Western Tanager Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Western Tanager population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Northern Pacific Rainforest-13%1970139
Great Basin+128%1970171
Northern Rockies+117%1970186
Sierra Nevada+10%197040
Southern Rockies / Colorado Plateau+213%1970188
Badlands and Prairies+51%196947
Shortgrass Prairie+34%19967
Coastal California-32%197086
Sonoran and Mojave Deserts-80%197416
Sierra Madre Occidental+702%197030
Chihuahuan Desert14×197713

Western Tanager Conservation Status

Our route-weighted index shows it up about 598% since 1969.

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14. Trend is a route-weighted relative-abundance index, not an absolute population.