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Species · Delaware · BBS 2026 Release · 1966–2025

Blue-gray Gnatcatcher Population Trend in Delaware

All statesForest birds

Blue-gray Gnatcatcher in Delaware has surged: up 17× on the route-weighted index since 1969.

17×Since 1969TrendPercent 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 →
16Routes 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 →
54YearsYears 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 DelawareNotable 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 Delaware: up 17× on the route-weighted index since 1969.

Blue-gray Gnatcatcher Population Forecast in Delaware

If the recent trend holds, Blue-gray Gnatcatcher in Delaware is projected to fall about 37% by 2030 — from 6.5 in 2025 to a central estimate of 4.1 (95% range 1.3–6.9). A 5-year backtest shows a typical error of ±54.4%, with 40% of held-out values landing inside the 95% band.

-37%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 →
4.1Projected 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 →
1.3–6.995% 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 →
±54.4%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 Delaware is projected to fall about 37% by 2030 — from 6.5 in 2025 to a central estimate of 4.1 (95% range 1.3–6.9). A 5-year backtest shows a typical error of ±54.4%, with 40% 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 →
20263.81.06.6
20273.91.16.6
20283.91.26.7
20294.01.36.8
20304.11.36.9

Blue-gray Gnatcatcher Survey Routes in Delaware

Routes recording Blue-gray Gnatcatcher in Delaware.
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 →
Frederica1320251970
Pepperbox1020161998
Pepperbox 2920252017
Millsboro820252017
Frankford620081966
Milton 2620252017
Holleyville420041966
Harrington320251972
Lowes Xrds219911966
Milton220161966
Holleyville 2220242009
Mt Pleasant120191970
Wilmington120101979
Dover119661966
Blackbird120231995
Georgetown120221992

Blue-gray Gnatcatcher Population Trend in Other States

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

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