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

Brown-headed Cowbird Population Trend in North Carolina

All statesGeneralists

Brown-headed Cowbird in North Carolina has surged: up 188% on the route-weighted index since 1968.

+188%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 →
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 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 188% 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 38% by 2029 — from 7.1 in 2024 to a central estimate of 9.8 (95% range 4.2–15). A 5-year backtest shows a typical error of ±33.4%, with 100% of held-out values landing inside the 95% band.

+38%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 →
9.8Projected 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 →
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 →
±33.4%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 38% by 2029 — from 7.1 in 2024 to a central estimate of 9.8 (95% range 4.2–15). A 5-year backtest shows a typical error of ±33.4%, 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 →
20259.64.015
20269.64.015
20279.74.115
20289.74.115
20299.84.215

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
Maple Hill2420231995
Dudley2120242002
Monticello2020241990
Bethel1820242002
Milltail Cr1720241992
Sheep Ridge1720241994
Chowan River1720062002
Shallotte1619911967
Jarvisburg1619991992
Myrtle Grove1520241967
Flay1520241990
Jones Corner1520241994
Arapahoe1419951969
Ostwalt1420242012
Cypress Lakes1420242004
Green Swamp1420062002
Kinston1320241966
Youngsville1320241967
Call1320241969
Mooresville1220011966
Hulls Xroads1220231997
Dortches1220241990
Climax1120241966
California 21120242014

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 2026-05-22.