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Species · Connecticut · BBS 2025 Release · 1966–2024

Blue-gray Gnatcatcher Population Trend in Connecticut

All statesForest birds

Blue-gray Gnatcatcher in Connecticut has surged: up 11× on the route-weighted index since 1977.

11×Since 1977TrendPercent 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 →
20Routes 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 →
49YearsYears 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 ConnecticutNotable 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 Connecticut: up 11× on the route-weighted index since 1977.

Blue-gray Gnatcatcher Population Forecast in Connecticut

If the recent trend holds, Blue-gray Gnatcatcher in Connecticut is projected to fall about 15% by 2029 — from 2.3 in 2024 to a central estimate of 2.0 (95% range 0.94–3.0). A 5-year backtest shows a typical error of ±35.8%, with 100% of held-out values landing inside the 95% band.

-15%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 →
2.0Projected 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 →
0.94–3.095% 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 →
±35.8%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 Connecticut is projected to fall about 15% by 2029 — from 2.3 in 2024 to a central estimate of 2.0 (95% range 0.94–3.0). A 5-year backtest shows a typical error of ±35.8%, with 100% of held-out values landing inside the 95% band.19752029
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 →
20251.80.812.9
20261.90.842.9
20271.90.872.9
20281.90.913.0
20292.00.943.0

Blue-gray Gnatcatcher Survey Routes in Connecticut

Routes recording Blue-gray Gnatcatcher in Connecticut.
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 →
Uncasville920241980
Long Hill620191981
Woodstock520071979
Willimantic520181983
Sherman520191975
No Woodbury420241975
Woodstock 2420242017
Warren 2420242017
Mystic220231977
E Hartland219921992
Warren220101978
Mid Haddam220231977
Buckingham120141982
Westbrook120121989
Greenwich119951976
Danbury120161976
Southington120212017
New Hartford119871978
New Hartford120011996
Granby120231988

Blue-gray Gnatcatcher Population Trend in Other States

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