BirdAnalyst
Species · BBS 2026 Release · 1966–2025

Cerulean Warbler Population Analysis

ParulidaeForest birdsSetophaga cerulea

Cerulean Warbler has fallen sharply: down 59% on the route-weighted index since 1968.

-59%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 →
515RoutesSurvey 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 Cerulean Warbler

The Cerulean Warbler (Setophaga cerulea) 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 515 Breeding Bird Survey routes across 26 states, most concentrated in the Appalachian Mountains.
Family
Parulidae · Forest birds

Notable Cerulean 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 →

long arc declinecomputed 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 →

Cerulean Warbler has fallen sharply in surveyed states: down 59% on the route-weighted index since 1968.

Cerulean Warbler Population Forecast

If the recent trend holds, Cerulean Warbler is projected to rise about 24% by 2030 — from 0.06 in 2025 to a central estimate of 0.07 (95% range 0.01–0.14). A 5-year backtest shows a typical error of ±15.7%, with 100% of held-out values landing inside the 95% band.

+24%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 →
0.07Projected 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 →
0.01–0.1495% 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 →
±15.7%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, Cerulean Warbler is projected to rise about 24% by 2030 — from 0.06 in 2025 to a central estimate of 0.07 (95% range 0.01–0.14). A 5-year backtest shows a typical error of ±15.7%, 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 →
20260.080.010.14
20270.080.010.14
20280.070.010.14
20290.070.010.14
20300.070.010.14

Where the Cerulean Warbler Is Detected

BBS routes recording Cerulean Warbler, sized by most recent count.

Cerulean Warbler Population Trend by State

Cerulean 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 →
Alabama-19%197011
Arkansas-37%196918
Connecticut+43%19906
Georgiainsufficient datan/a1
Illinois-49%197313
Indiana-56%196828
Kentucky-73%196838
Louisianainsufficient datan/a1
Maryland+123%196827
Massachusettsinsufficient datan/a3
Michigan+48%197120
Minnesota-87%19744
Mississippiinsufficient datan/a3
Missouri+50%197623
New Hampshireinsufficient datan/a1
New Jersey+70%19805
New York+15%196927
North Carolina-65%19926
Ohio-8%196855
Oklahomainsufficient datan/a4
Pennsylvania-10%196877
Tennessee-21%196828
Vermontinsufficient datan/a4
Virginia+172%196829
West Virginia-48%196857
Wisconsin-10%197026

Cerulean Warbler Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Cerulean 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 Transition-34%199410
Lower Great Lakes / St. Lawrence Plain-61%196838
Atlantic Northern Forest+79%19788
Eastern Tallgrass Prairie-75%197229
Prairie Hardwood Transition-42%197046
Central Hardwoods-56%196884
West Gulf Coastal Plain / Ouachitas-71%197011
Mississippi Alluvial Valley-77%19724
Southeastern Coastal Plain-23%197316
Appalachian Mountains-22%1968240
Piedmont-83%196819
New England / Mid-Atlantic Coast+28%197910

Cerulean Warbler Conservation Status

Our route-weighted index shows it down about 59% 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.