BirdAnalyst
Species · North Carolina · BBS 2026 Release · 1966–2025

Brown-headed Cowbird Population Trend in North Carolina

All statesGeneralists

Brown-headed Cowbird in North Carolina has surged: up 203% on the route-weighted index since 1968.

+203%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 →
108Routes 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 →
59YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Brown-headed Cowbird 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 →

Brown-headed Cowbird has surged in North Carolina: up 203% on the route-weighted index since 1968.

Brown-headed Cowbird Population Forecast in North Carolina

If the recent trend holds, Brown-headed Cowbird in North Carolina is projected to rise about 22% by 2030 — from 8.0 in 2025 to a central estimate of 9.7 (95% range 4.2–15). A 5-year backtest shows a typical error of ±33%, with 100% of held-out values landing inside the 95% band.

+22%Change by 2030TrendPercent 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 →
9.7Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
4.2–1595% 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 →
±33%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, Brown-headed Cowbird in North Carolina is projected to rise about 22% by 2030 — from 8.0 in 2025 to a central estimate of 9.7 (95% range 4.2–15). A 5-year backtest shows a typical error of ±33%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20269.54.015
20279.64.015
20289.64.115
20299.74.115
20309.74.215

Brown-headed Cowbird Survey Routes in North Carolina

Routes recording Brown-headed Cowbird 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 →
Mashoes6919821971
Cypress Lakes2520252004
Maple Hill2420231995
Genoa2120251990
Sheep Ridge2020251994
Supply1920251992
Dortches1920251990
Montague1820251990
California 21720252014
Chowan River1720062002
Shallotte1619911967
Monticello1620251990
Jarvisburg1619991992
Dudley1520252002
Arapahoe1419951969
Milltail Cr1420251992
Bullock1420251997
Green Swamp1420062002
Kinston1320241966
Oakboro1320251969
Jamesville1320251983
Mooresville1220011966
Youngsville1220251967
Hulls Xroads1220231997
Jarvisburg 21220252000

Brown-headed Cowbird Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.