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

Northern Mockingbird Population Trend in Illinois

All statesGeneralists

Northern Mockingbird in Illinois has declined: down 48% on the route-weighted index since 1968.

-48%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 →
88Routes 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 →
59YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Northern Mockingbird Trends in IllinoisNotable 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 Northern Mockingbird in Illinois. See the full index history below.

Northern Mockingbird Population Forecast in Illinois

If the recent trend holds, Northern Mockingbird in Illinois is projected to fall about 43% by 2030 — from 2.3 in 2025 to a central estimate of 1.3 (95% range 0.00–4.1). A 5-year backtest shows a typical error of ±21.5%, with 100% of held-out values landing inside the 95% band.

-43%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 →
1.3Projected 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 →
0.00–4.195% 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 →
±21.5%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, Northern Mockingbird in Illinois is projected to fall about 43% by 2030 — from 2.3 in 2025 to a central estimate of 1.3 (95% range 0.00–4.1). A 5-year backtest shows a typical error of ±21.5%, 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 →
20261.60.004.4
20271.50.004.3
20281.50.004.2
20291.40.004.2
20301.30.004.1

Northern Mockingbird Survey Routes in Illinois

Routes recording Northern Mockingbird in Illinois.
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 →
Royalton1720252001
Mt Vernon1620251971
Columbia1520251966
Belknap1220251970
Kell1120252001
Karnak1020252001
Bremen920251969
Jamestown820251966
Olney820241966
Brnt Prairie720251976
Cave In Rock720241993
Birds620241976
Pulaski620251970
Delwood620251970
York620251993
Concord520251967
Martinsville420251970
Mascoutah Lk420251967
St Morgan420221967
Beaverdam Lk420231970
Brownville420251993
Eubanks420182001
Marshall420252002
Bluff Spgs320251967
Yale320251993

Northern Mockingbird Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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