BirdAnalyst
Species · California · BBS 2026 Release · 1966–2025

Red Crossbill Population Trend in California

All statesForest birds

Red Crossbill in California has surged: up 314% on the route-weighted index since 1971.

+314%Since 1971TrendPercent 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 →
83Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Red Crossbill 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 →

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 →

Red Crossbill has surged in California: up 314% on the route-weighted index since 1971.

Red Crossbill Population Forecast in California

If the recent trend holds, Red Crossbill in California is projected to fall about 40% by 2030 — from 1.0 in 2025 to a central estimate of 0.61 (95% range 0.04–1.2). A 5-year backtest shows a typical error of ±95.1%, with 100% of held-out values landing inside the 95% band.

-40%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 →
0.61Projected 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 →
0.04–1.295% 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 →
±95.1%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, Red Crossbill in California is projected to fall about 40% by 2030 — from 1.0 in 2025 to a central estimate of 0.61 (95% range 0.04–1.2). A 5-year backtest shows a typical error of ±95.1%, with 100% of held-out values landing inside the 95% band.19692030
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 →
20260.590.011.2
20270.590.021.2
20280.600.031.2
20290.610.031.2
20300.610.041.2

Red Crossbill Survey Routes in California

Routes recording Red Crossbill 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 →
Eagle Lake4020251969
Redwood N.P. 22420132012
Westville2320251981
Tionesta2020211997
Crestview1620251997
Rio Dell1420051991
Little Truckee1120231997
Chilcoot1120241998
Dirigio1020062002
South Fork Mtn920182003
Crowder Flat820192002
Strawberry820012001
Clear Lk Res720141979
Horse Creek619921989
Big Bear619691969
Shasta Lake620241983
Mccloud620211985
Korbel620141973
Hackamore620102001
Tujunga519761976
Greenhorn Mt519961971
Valyermo520191979
Tuolumne Grove520251974
Mt Shasta520181980
Coulterville520022002

Red Crossbill Population Trend in Other States

alabamaalaskaarizonaarkansascoloradogeorgiaidahoillinoismainemarylandmassachusettsmichiganminnesotamontananebraskanevadanew-hampshirenew-mexiconew-yorknorth-carolinanorth-dakotaoregonpennsylvaniasouth-carolinasouth-dakotatennesseeutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.