BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Cape May Warbler

ParulidaeForest birdsSetophaga tigrina

Cape May Warbler has surged: up 113% on the route-weighted index since 1969.

+113%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 →
169RoutesSurvey 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 Cape May Warbler

The Cape May Warbler (Setophaga tigrina) is a North American member of the Wood-Warblers (Parulidae). In this analysis it is grouped with the forest birds.

Size
4.5–5.5 in long (11–14 cm) — a small, active 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 169 Breeding Bird Survey routes across 7 states, most concentrated in the Atlantic Northern Forest.
Family
Parulidae · Forest birds

Notable Cape May Warbler TrendsNotable 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 Cape May Warbler. See the full index history below.

Cape May Warbler Population Forecast

If the recent trend holds, Cape May Warbler is projected to stay roughly flat through 2029, near 0.02 (95% range 0.00–0.03). A 5-year backtest shows a typical error of ±26.7%, with 80% of held-out values landing inside the 95% band.

n/aChange 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 →
0.02Projected 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 →
0.00–0.0395% 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 →
±26.7%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 is projected to stay roughly flat through 2029, near 0.02 (95% range 0.00–0.03). A 5-year backtest shows a typical error of ±26.7%, with 80% of held-out values landing inside the 95% band.19672029
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 →
20250.020.000.03
20260.020.000.03
20270.020.000.03
20280.020.000.03
20290.020.000.03

Where the Cape May Warbler Is Detected

BBS routes recording Cape May Warbler, sized by most recent count.

Cape May Warbler Population Trend by State

Cape May Warbler 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 →
Maine-74%197457
Michigan-1%197834
Minnesota+719%197026
New Hampshire-66%196912
New York+70%197612
Vermontinsufficient datan/a5
Wisconsin+342%197423

Cape May Warbler Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Cape May Warbler 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 Transition14×197077
Atlantic Northern Forest-54%196984

Cape May Warbler Conservation Status

Our route-weighted index shows it up about 113% since 1969.

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.