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

Gray Partridge Population Trend in Iowa

All statesGeneralists

Gray Partridge in Iowa has surged: up 83% on the route-weighted index since 1970.

+83%Since 1970TrendPercent 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 →
26Routes 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 →
55YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Gray Partridge Trends in IowaNotable 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 →

Gray Partridge has surged in Iowa: up 83% on the route-weighted index since 1970.

Gray Partridge Population Forecast in Iowa

If the recent trend holds, Gray Partridge in Iowa is projected to fall about 58% by 2029 — from 0.36 in 2024 to a central estimate of 0.15 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±177.7%, with 100% of held-out values landing inside the 95% band.

-58%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 →
0.15Projected 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 →
0.00–1.495% 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 →
±177.7%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, Gray Partridge in Iowa is projected to fall about 58% by 2029 — from 0.36 in 2024 to a central estimate of 0.15 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±177.7%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20250.220.001.5
20260.200.001.4
20270.180.001.4
20280.170.001.4
20290.150.001.4

Gray Partridge Survey Routes in Iowa

Routes recording Gray Partridge in Iowa.
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 →
Bedford919891989
Garner819901973
Bryant619981988
Cedar Valley419911987
Zearing419941977
Burchinal320151995
Gaza320151969
Panther220101987
Washington220091984
Alice219971997
Prairieburg219931993
Kanawha220241973
Scranton220141975
Pierson220181968
Davis Corner220241988
Rock Valley220011968
Mccallsburg220241996
Brooklyn120151984
Williamsburg119961993
Hudson120211984
Dinsdale119921985
Clare120171973
Washta119901971
Sioux City119901978
Festina120241985

Gray Partridge Population Trend in Other States

idahoillinoisindianaminnesotamontananebraskanevadanew-yorknorth-dakotaoregonsouth-dakotautahwashingtonwisconsinwyoming

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