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

Blue-gray Gnatcatcher Population Trend in Iowa

All statesForest birds

Blue-gray Gnatcatcher in Iowa has increased: up 28% on the route-weighted index since 1980.

+28%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 →
42YearsYears 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 →

No notable trend signals for Blue-gray Gnatcatcher in Iowa. See the full index history below.

Blue-gray Gnatcatcher Population Forecast in Iowa

If the recent trend holds, Blue-gray Gnatcatcher in Iowa is projected to fall about 26% by 2029 — from 0.14 in 2024 to a central estimate of 0.10 (95% range 0.00–0.30). A 5-year backtest shows a typical error of ±58.3%, with 100% of held-out values landing inside the 95% band.

-26%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 →
0.10Projected 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 →
0.00–0.3095% 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 →
±58.3%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 26% by 2029 — from 0.14 in 2024 to a central estimate of 0.10 (95% range 0.00–0.30). A 5-year backtest shows a typical error of ±58.3%, with 100% of held-out values landing inside the 95% band.19742029
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 →
20250.110.000.31
20260.100.000.31
20270.100.000.30
20280.100.000.30
20290.100.000.30

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 →
West Liberty219911991
Brooklyn220062003
Maquoketa220191993
Washta220102008
Mt Hamill120241974
Exline120232007
Melrose120242002
Bedford120172007
Cedar Valley119961979
College Spgs 2120172017
Red Rock120042004
Tipton119941993
Panther120161987
Wales120142014
Prairieburg119901990
Hudson120122012
Lafayette120242003
Festina120131980

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 2026-05-22.