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

Blue Jay Population Trend in Colorado

All statesGeneralists

Blue Jay in Colorado has increased: up 27% on the route-weighted index since 1975.

+27%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 →
40Routes 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 →
46YearsYears 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 Jay Trends in ColoradoNotable 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 Jay in Colorado. See the full index history below.

Blue Jay Population Forecast in Colorado

If the recent trend holds, Blue Jay in Colorado is projected to rise about 32% by 2029 — from 0.09 in 2024 to a central estimate of 0.12 (95% range 0.04–0.21). A 5-year backtest shows a typical error of ±26.2%, with 100% of held-out values landing inside the 95% band.

+32%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 →
0.12Projected 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 →
0.04–0.2195% 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 →
±26.2%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 Jay in Colorado is projected to rise about 32% by 2029 — from 0.09 in 2024 to a central estimate of 0.12 (95% range 0.04–0.21). A 5-year backtest shows a typical error of ±26.2%, 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 →
20250.120.040.20
20260.120.040.20
20270.120.040.20
20280.120.040.20
20290.120.040.21

Blue Jay Survey Routes in Colorado

Routes recording Blue Jay in Colorado.
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 →
Harmony320241982
Julesburg320161998
Arsenal220141998
Arsenal 2220242016
Summitville219991999
Wildhorse L220241998
Doyle Bridge 2220181999
Adams Co.220211998
Fort Morgan220241996
Limon220192019
Gardner219991999
Briggsdale120181977
Pinneo120092001
Fleming120211972
Cheesman Lk120192019
Kiowa120141975
Abarr120211980
Rush120182018
Boyero120071997
Lamar120181975
Two Buttes119811980
Hudson120221994
Waverly119941992
Gordon Creek119961995
Bethune119891989

Blue Jay Population Trend in Other States

alabamaarkansasconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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