BirdAnalyst
Species · BBS 2026 Release · 1966–2025

Winter Wren Population Analysis

TroglodytidaeForest birdsTroglodytes hiemalis

Winter Wren has risen sharply: up 55% on the route-weighted index since 1968.

+55%Since 1968TrendPercent 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 →
490RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
59Years 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 Winter Wren

The Winter Wren (Troglodytes hiemalis) 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 490 Breeding Bird Survey routes across 17 states, most concentrated in the Atlantic Northern Forest.
Family
Troglodytidae · Forest birds

Notable Winter 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 →

Winter Wren has risen sharply in surveyed states: up 55% on the route-weighted index since 1968.

Winter Wren Population Forecast

If the recent trend holds, Winter Wren is projected to rise about 93% by 2030 — from 0.18 in 2025 to a central estimate of 0.35 (95% range 0.11–0.59). A 5-year backtest shows a typical error of ±74.2%, with 100% of held-out values landing inside the 95% band.

+93%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 →
0.35Projected 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 →
0.11–0.5995% 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 →
±74.2%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, Winter Wren is projected to rise about 93% by 2030 — from 0.18 in 2025 to a central estimate of 0.35 (95% range 0.11–0.59). A 5-year backtest shows a typical error of ±74.2%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20260.340.110.58
20270.340.110.58
20280.350.110.58
20290.350.110.58
20300.350.110.59

Where the Winter Wren Is Detected

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

Winter Wren Population Trend by State

Winter 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 →
Connecticut+32%197315
Maine+9%196877
Maryland+48%19936
Massachusetts+247%196920
Michigan+458%196859
Minnesota+331%196934
New Hampshire+50%196826
New Jerseyinsufficient datan/a1
New York+497%196881
North Carolina-51%19799
Ohioinsufficient datan/a1
Pennsylvania13×197658
Tennessee12×19764
Vermont+355%196826
Virginia-18%198310
West Virginia+320%197514
Wisconsin+100%196849

Winter Wren Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Winter 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 →
Boreal Hardwood Transition+216%1968117
Lower Great Lakes / St. Lawrence Plain+730%197236
Atlantic Northern Forest+101%1968154
Prairie Hardwood Transition-40%197124
Appalachian Mountains24×1971126
New England / Mid-Atlantic Coast+86%197132

Winter Wren Conservation Status

Our route-weighted index shows it up about 54% since 1968.

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