BirdAnalyst
Species · North Carolina · BBS 2025 Release · 1966–2024

Blue Grosbeak Population Trend in North Carolina

All statesGeneralists

Blue Grosbeak in North Carolina has risen sharply: up 50% on the route-weighted index since 1968.

+50%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 →
101Routes 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 Blue Grosbeak Trends in North CarolinaNotable 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 Grosbeak has risen sharply in North Carolina: up 50% on the route-weighted index since 1968.

Blue Grosbeak Population Forecast in North Carolina

If the recent trend holds, Blue Grosbeak in North Carolina is projected to rise about 21% by 2029 — from 8.6 in 2024 to a central estimate of 10 (95% range 5.9–15). A 5-year backtest shows a typical error of ±20.7%, with 100% of held-out values landing inside the 95% band.

+21%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 →
10Projected 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 →
5.9–1595% 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 →
±20.7%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 Grosbeak in North Carolina is projected to rise about 21% by 2029 — from 8.6 in 2024 to a central estimate of 10 (95% range 5.9–15). A 5-year backtest shows a typical error of ±20.7%, 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 →
2025105.715
2026105.815
2027105.815
2028105.915
2029105.915

Blue Grosbeak Survey Routes in North Carolina

Routes recording Blue Grosbeak in North Carolina.
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 →
Speed3920241966
Jackson3420171995
Kinston2620241966
Rhems2619931990
Dudley2520242002
Cypress Lakes2520242006
Shallotte2319911966
Beargrass2319811969
Cypress Cr2320221990
Pinetops2320241997
Montague2120241990
California2020131972
Genoa2020241990
Maple Hill1920231995
Congleton1920242001
Oakboro1820241969
Bullock1820241997
Bethel1820242002
Fairmont1619811968
Youngsville1620241966
Biscoe1620171990
Hertford1620241997
Wards Corner1520241966
Rowland1520241990
Jamesville1520241983

Blue Grosbeak Population Trend in Other States

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