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

Rose-breasted Grosbeak Population Trend in Connecticut

All statesGeneralists

Rose-breasted Grosbeak in Connecticut has fallen sharply: down 72% on the route-weighted index since 1968.

-72%Since 1968TrendPercent 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 →
58YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Rose-breasted Grosbeak 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 declinecomputed 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 →

Rose-breasted Grosbeak has fallen sharply in Connecticut: down 72% on the route-weighted index since 1968.

Rose-breasted Grosbeak Population Forecast in Connecticut

If the recent trend holds, Rose-breasted Grosbeak in Connecticut is projected to fall about 94% by 2029 — from 1.9 in 2024 to a central estimate of 0.11 (95% range 0.00–2.5). A 5-year backtest shows a typical error of ±82.2%, with 100% of held-out values landing inside the 95% band.

-94%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 →
0.11Projected 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 →
0.00–2.595% 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 →
±82.2%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, Rose-breasted Grosbeak in Connecticut is projected to fall about 94% by 2029 — from 1.9 in 2024 to a central estimate of 0.11 (95% range 0.00–2.5). A 5-year backtest shows a typical error of ±82.2%, with 100% 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 →
20250.520.002.9
20260.420.002.8
20270.320.002.7
20280.210.002.6
20290.110.002.5

Rose-breasted Grosbeak Survey Routes in Connecticut

Routes recording Rose-breasted Grosbeak 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 →
Willimantic820181967
New Hartford719871972
Long Hill520191973
Buckingham420221966
Uncasville420241973
E Hartland319921966
Westbrook320241972
Sherman320191972
Warren320111972
Woodstock220071968
Greenwich220181967
Danbury220161968
Southington220241973
Woodstock 2220242016
Granby220241989
Mystic120231973
No Woodbury120241967
Mid Haddam120241973
New Hartford120241994
Warren 2120242012

Rose-breasted Grosbeak Population Trend in Other States

arkansasgeorgiaillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamissourinebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-dakotatennesseevermontvirginiawest-virginiawisconsinwyoming

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