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Species · Iowa · BBS 2026 Release · 1966–2025

Blue-gray Gnatcatcher Population Trend in Iowa

All statesForest birds

Blue-gray Gnatcatcher in Iowa has surged: up 122% on the route-weighted index since 1980.

+122%Since 1980TrendPercent 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 →
18Routes 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 →
43YearsYears 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-gray Gnatcatcher 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 →

Blue-gray Gnatcatcher has surged in Iowa: up 122% on the route-weighted index since 1980.

Blue-gray Gnatcatcher Population Forecast in Iowa

If the recent trend holds, Blue-gray Gnatcatcher in Iowa is projected to fall about 62% by 2030 — from 0.32 in 2025 to a central estimate of 0.12 (95% range 0.00–0.33). A 5-year backtest shows a typical error of ±60%, with 80% of held-out values landing inside the 95% band.

-62%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 →
0.12Projected 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 →
0.00–0.3395% 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 →
±60%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-gray Gnatcatcher in Iowa is projected to fall about 62% by 2030 — from 0.32 in 2025 to a central estimate of 0.12 (95% range 0.00–0.33). A 5-year backtest shows a typical error of ±60%, with 80% of held-out values landing inside the 95% band.19742030
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 →
20260.130.000.34
20270.130.000.33
20280.130.000.33
20290.120.000.33
20300.120.000.33

Blue-gray Gnatcatcher Survey Routes in Iowa

Routes recording Blue-gray Gnatcatcher 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 →
Mt Hamill520251974
Exline220252007
Brooklyn220062003
Maquoketa220191993
Washta220102008
Melrose120242002
Bedford120252007
West Liberty120251991
Cedar Valley119961979
College Spgs 2120172017
Red Rock120042004
Tipton119941993
Panther120161987
Wales120142014
Prairieburg119901990
Hudson120122012
Lafayette120242003
Festina120251980

Blue-gray Gnatcatcher Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawest-virginiawisconsinwyoming

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