BirdAnalyst
Species · BCR 35 · BBS 2026 Release · 1966–2025

Brown-headed Cowbird In Chihuahuan Desert

All regionsChihuahuan DesertGeneralists

Brown-headed Cowbird in Chihuahuan Desert has fallen sharply: down 71% on the route-weighted index since 1969.

-71%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 →
57Routes In RegionSurvey 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 SignalsNotable 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 →

Brown-headed Cowbird has fallen sharply in Chihuahuan Desert: down 71% on the route-weighted index since 1969.

Brown-headed Cowbird In Chihuahuan Desert Population Forecast

If the recent trend holds, Brown-headed Cowbird in Chihuahuan Desert is projected to rise about 81% by 2030 — from 2.9 in 2025 to a central estimate of 5.2 (95% range 0.00–14). A 5-year backtest shows a typical error of ±91.8%, with 100% of held-out values landing inside the 95% band.

+81%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 →
5.2Projected 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 →
0.00–1495% 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 →
±91.8%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 Chihuahuan Desert is projected to rise about 81% by 2030 — from 2.9 in 2025 to a central estimate of 5.2 (95% range 0.00–14). A 5-year backtest shows a typical error of ±91.8%, with 100% of held-out values landing inside the 95% band.19672030
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 →
20265.50.0014
20275.40.0014
20285.40.0014
20295.30.0014
20305.20.0014

Routes In Chihuahuan Desert

Routes recording Brown-headed Cowbird in Chihuahuan Desert.
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 →
Quitman Cyn.TEXAS292009
MesillaNEW-MEXICO202000
San AntonioNEW-MEXICO171977
ShafterTEXAS161985
Devils R CynTEXAS162025
Sunshine WllNEW-MEXICO102021
Red RockNEW-MEXICO92025
OzonaTEXAS82022
PumpvilleTEXAS82025
Laborcita 2NEW-MEXICO72025
Ozona 2TEXAS72025
ComstockTEXAS62025
Delaware CrkTEXAS62015
LaborcitaNEW-MEXICO52019
LangtryTEXAS52000
CastolonTEXAS52025
Salt FlatTEXAS52015
Ft. DavisTEXAS52025
Chisos BasinTEXAS52019
PinonNEW-MEXICO42024
Lake ValleyNEW-MEXICO42024
Casa PiedraTEXAS42025
Ft. StocktonTEXAS42025
Quitman Canyon 2TEXAS42025
Bitter LakeNEW-MEXICO32022

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