BirdAnalyst
Species · California · BBS 2025 Release · 1966–2024

Blue-winged Teal Population Trend in California

All statesWaterfowl

Blue-winged Teal in California has surged: up 165% on the route-weighted index since 1975.

+165%Since 1975TrendPercent 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 →
18Routes 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 →
45YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Blue-winged Teal Trends in CaliforniaNotable 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 Blue-winged Teal in California. See the full index history below.

Blue-winged Teal Population Forecast in California

If the recent trend holds, Blue-winged Teal in California is projected to fall about 30% by 2029 — from 0.05 in 2024 to a central estimate of 0.04 (95% range 0.00–0.10). A 5-year backtest shows a typical error of ±57.2%, with 100% of held-out values landing inside the 95% band.

-30%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 →
0.04Projected 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 →
0.00–0.1095% 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 →
±57.2%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, Blue-winged Teal in California is projected to fall about 30% by 2029 — from 0.05 in 2024 to a central estimate of 0.04 (95% range 0.00–0.10). A 5-year backtest shows a typical error of ±57.2%, with 100% of held-out values landing inside the 95% band.19722029
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 →
20250.040.000.10
20260.040.000.10
20270.040.000.10
20280.040.000.10
20290.040.000.10

Blue-winged Teal Survey Routes in California

Routes recording Blue-winged Teal in California.
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 →
Dorris620191972
Honey Lake520241998
Crescent Cty319801980
Bartle319841981
Davis Creek219801980
Bodega Bay219751975
Macdoel219991999
Iron Gate220151989
Arvin219861986
Benton220231975
Likely219891975
Tehama119891989
Nubieber120072000
Ingalls119801973
Yreka119931977
Orland119871985
Clear Lk Res120041980
Glenn120071977

Blue-winged Teal Population Trend in Other States

alabamaalaskaarizonaarkansascoloradodelawarefloridaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-mexiconew-yorknorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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