BirdAnalyst
Species · New Jersey · BBS 2025 Release · 1966–2024

Rose-breasted Grosbeak Population Trend in New Jersey

All statesGeneralists

Rose-breasted Grosbeak in New Jersey has risen sharply: up 63% on the route-weighted index since 1969.

+63%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 →
22Routes 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 →
57YearsYears 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 New JerseyNotable 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 →

Rose-breasted Grosbeak has risen sharply in New Jersey: up 63% on the route-weighted index since 1969.

Rose-breasted Grosbeak Population Forecast in New Jersey

If the recent trend holds, Rose-breasted Grosbeak in New Jersey is projected to fall about 44% by 2029 — from 0.52 in 2024 to a central estimate of 0.29 (95% range 0.00–0.94). A 5-year backtest shows a typical error of ±44.3%, with 100% of held-out values landing inside the 95% band.

-44%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 →
0.29Projected 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 →
0.00–0.9495% 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 →
±44.3%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, Rose-breasted Grosbeak in New Jersey is projected to fall about 44% by 2029 — from 0.52 in 2024 to a central estimate of 0.29 (95% range 0.00–0.94). A 5-year backtest shows a typical error of ±44.3%, 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 →
20250.330.000.97
20260.320.000.96
20270.310.000.95
20280.300.000.94
20290.290.000.94

Rose-breasted Grosbeak Survey Routes in New Jersey

Routes recording Rose-breasted Grosbeak in New Jersey.
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 →
Kemah Lake420231966
High Point420241977
Sandbrook220241969
Pottersville220221977
Gillette220241988
Ramseysburg220241995
Albion119681968
Holmansville119961969
Clarksville119911969
New Bedford120242024
Croton120071970
Robbinsville119741969
Hope119941970
Midvale120051970
Bloomsbury120121970
Dover120221977
Keyport120031995
Cranbury119931987
Roosevelt120181986
Friendship119821982
Winslow120061990
Croton 2120222011

Rose-breasted Grosbeak Population Trend in Other States

arkansasconnecticutgeorgiaillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamissourinebraskanew-hampshirenew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-dakotatennesseevermontvirginiawest-virginiawisconsinwyoming

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