BirdAnalyst
Species · BBS 2026 Release · 1966–2025

Pacific Wren Population Analysis

TroglodytidaeForest birdsTroglodytes pacificus

Pacific Wren has surged: up 468% on the route-weighted index since 1970.

+468%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 →
289RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
57Years 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 Pacific Wren

The Pacific Wren (Troglodytes pacificus) is a North American member of the Wrens (Troglodytidae). In this analysis it is grouped with the forest birds.

Size
4–8.5 in long (10–22 cm) — a small, energetic 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 289 Breeding Bird Survey routes across 8 states, most concentrated in the Northern Pacific Rainforest.
Family
Troglodytidae · Forest birds

Notable Pacific Wren 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 →

Pacific Wren has surged in surveyed states: up 468% on the route-weighted index since 1970.

Pacific Wren Population Forecast

If the recent trend holds, Pacific Wren is projected to rise about 70% by 2030 — from 0.46 in 2025 to a central estimate of 0.79 (95% range 0.48–1.1). A 5-year backtest shows a typical error of ±56%, with 40% of held-out values landing inside the 95% band.

+70%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 →
0.79Projected 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 →
0.48–1.195% 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 →
±56%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, Pacific Wren is projected to rise about 70% by 2030 — from 0.46 in 2025 to a central estimate of 0.79 (95% range 0.48–1.1). A 5-year backtest shows a typical error of ±56%, with 40% 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 →
20260.750.451.0
20270.760.461.1
20280.770.461.1
20290.780.471.1
20300.790.481.1

Where the Pacific Wren Is Detected

BBS routes recording Pacific Wren, sized by most recent count.

Pacific Wren Population Trend by State

Pacific Wren 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-11%197437
California+460%197063
Idaho+572%197619
Montana+320%197123
Nevadainsufficient datan/a1
Oregon+104%197072
South Dakotainsufficient datan/a1
Washington+11%197073

Pacific Wren Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Pacific Wren 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 →
BCR 2-15%19853
Northern Pacific Rainforest+145%1970143
Great Basin+106%197031
Northern Rockies+525%197074
Sierra Nevada+287%197419
Coastal California20×197612

Pacific Wren Conservation Status

Our route-weighted index shows it up about 468% since 1970.

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