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

Blue Jay Population Trend in Illinois

All statesGeneralists

Blue Jay in Illinois has fallen sharply: down 54% on the route-weighted index since 1968.

-54%Since 1968
105Routes In State
58Years

Notable Blue Jay Trends in Illinois

long arc declinecomputed index

Blue Jay has fallen sharply in Illinois: down 54% on the route-weighted index since 1968.

Blue Jay Population Forecast in Illinois

If the recent trend holds, Blue Jay in Illinois is projected to fall about 25% by 2029 — from 5.5 in 2024 to a central estimate of 4.1 (95% range 1.9–6.3). A 5-year backtest shows a typical error of ±16.5%, with 100% of held-out values landing inside the 95% band.

-25%Change by 2029
4.1Projected 2029 index
1.9–6.395% range
±16.5%Backtest error
19662029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected index95% low95% high
20254.62.46.8
20264.52.26.7
20274.32.16.6
20284.22.06.4
20294.11.96.3

Blue Jay Survey Routes in Illinois

Routes recording Blue Jay in Illinois.
Wayne2620241966
Melrose2119991973
Terre Haute2020241966
Caledonia2020241993
Sheffield1720241966
Lake Galena1620212001
Eldred1420211993
Alden1320232019
Brnt Prairie1220241976
Mt Vernon1220241971
Duncan Mills1220241993
Guilford1020231967
Mill Creek1020241966
Geneseo1020211967
Athensville1020241971
St Morgan1020221967
Birds1020241976
Sherrard1020241993
Royalton1020242001
Concord920241967
Mascoutah Lk920241967
Belknap920241970
Camp Point920241993
Sandusky920231993
Union920172001

Blue Jay Population Trend in Other States

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

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