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Species · Wisconsin · BBS 2025 Release · 1966–2024

Cape May Warbler Population Trend in Wisconsin

All statesForest birds

Cape May Warbler in Wisconsin has surged: up 342% on the route-weighted index since 1974.

+342%Since 1974TrendPercent 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 →
50YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Cape May Warbler Trends in WisconsinNotable 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 →

Cape May Warbler has surged in Wisconsin: up 342% on the route-weighted index since 1974.

Cape May Warbler Population Forecast in Wisconsin

If the recent trend holds, Cape May Warbler in Wisconsin is projected to rise about 29% by 2029 — from 0.06 in 2024 to a central estimate of 0.08 (95% range 0.00–0.16). A 5-year backtest shows a typical error of ±38.2%, with 80% of held-out values landing inside the 95% band.

+29%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 →
0.08Projected 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 →
0.00–0.1695% 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 →
±38.2%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, Cape May Warbler in Wisconsin is projected to rise about 29% by 2029 — from 0.06 in 2024 to a central estimate of 0.08 (95% range 0.00–0.16). A 5-year backtest shows a typical error of ±38.2%, with 80% of held-out values landing inside the 95% band.19712029
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 →
20250.080.000.15
20260.080.000.16
20270.080.000.16
20280.080.000.16
20290.080.000.16

Cape May Warbler Survey Routes in Wisconsin

Routes recording Cape May Warbler in Wisconsin.
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 →
Eagle River620221975
Shanagolden420221975
Land O Lakes420161981
Popple River320241973
Minong219971971
Montreal219871979
Chaffey119971996
Iron River120182005
Grand View120101974
Bayfield119871971
Cumberland119981998
Couderay119841984
Phillips120071988
Merrill119911990
Mcnaughton120222008
Crandon120061976
Amberg120242013
Wausaukee120192019
Stevens Pt120162016
Oconto Falls120162016
Rhinelander120232009
Cavour120241998
Land O' Lakes 2120232019

Cape May Warbler Population Trend in Other States

mainemichiganminnesotanew-hampshirenew-yorkvermont

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