BirdAnalyst
Species · BCR 35 · BBS 2025 Release · 1966–2024

Brown-headed Cowbird In Chihuahuan Desert

All regionsChihuahuan DesertGeneralists

Brown-headed Cowbird in Chihuahuan Desert has fallen sharply: down 66% on the route-weighted index since 1969.

-66%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 →
56Routes 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 →
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 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 66% 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 56% by 2029 — from 3.6 in 2024 to a central estimate of 5.5 (95% range 0.00–14). A 5-year backtest shows a typical error of ±89.3%, with 100% of held-out values landing inside the 95% band.

+56%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 →
5.5Projected 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 →
0.00–1495% 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 →
±89.3%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, Brown-headed Cowbird in Chihuahuan Desert is projected to rise about 56% by 2029 — from 3.6 in 2024 to a central estimate of 5.5 (95% range 0.00–14). A 5-year backtest shows a typical error of ±89.3%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20255.80.0014
20265.70.0014
20275.70.0014
20285.60.0014
20295.50.0014

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
ColumbusNEW-MEXICO162024
ShafterTEXAS161985
Red RockNEW-MEXICO152024
MarathonTEXAS122022
Sunshine WllNEW-MEXICO102021
PumpvilleTEXAS102024
LongfellowTEXAS92024
OzonaTEXAS82022
Hatchet PeakNEW-MEXICO72024
ComstockTEXAS62023
Delaware CrkTEXAS62015
Sierra BlancTEXAS62023
Ft. DavisTEXAS62023
GageNEW-MEXICO52024
LaborcitaNEW-MEXICO52019
LangtryTEXAS52000
Devils R CynTEXAS52024
Salt FlatTEXAS52015
Chisos BasinTEXAS52019
PinonNEW-MEXICO42024
Lake ValleyNEW-MEXICO42024
Casa PiedraTEXAS42023

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