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Species · Delaware · BBS 2025 Release · 1966–2024

Blue-gray Gnatcatcher Population Trend in Delaware

All statesForest birds

Blue-gray Gnatcatcher in Delaware has surged: up 15× on the route-weighted index since 1969.

15×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 →
53YearsYears 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 15× 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 16% by 2029 — from 4.6 in 2024 to a central estimate of 3.9 (95% range 1.0–6.7). A 5-year backtest shows a typical error of ±55.5%, with 40% of held-out values landing inside the 95% band.

-16%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 →
3.9Projected 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 →
1.0–6.795% 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 →
±55.5%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, Blue-gray Gnatcatcher in Delaware is projected to fall about 16% by 2029 — from 4.6 in 2024 to a central estimate of 3.9 (95% range 1.0–6.7). A 5-year backtest shows a typical error of ±55.5%, with 40% of held-out values landing inside the 95% band.19662029
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 →
20253.60.756.4
20263.70.826.5
20273.70.896.6
20283.80.966.6
20293.91.06.7

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 →
Millsboro1020242017
Pepperbox1020161998
Harrington720241972
Frankford620081966
Milton 2520172017
Holleyville420041966
Pepperbox 2420242017
Lowes Xrds219911966
Milton220161966
Holleyville 2220242009
Mt Pleasant120191970
Wilmington120101979
Frederica120141970
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 2026-05-22.