BirdAnalyst
Species · BCR 16 · BBS 2025 Release · 1966–2024

Brown-headed Cowbird In Southern Rockies / Colorado Plateau

All regionsSouthern Rockies / Colorado PlateauGeneralists

Brown-headed Cowbird in Southern Rockies / Colorado Plateau has increased: up 49% on the route-weighted index since 1970.

+49%Since 1970TrendPercent 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 →
234Routes 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 →
56YearsYears 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 →

No notable trend signals for Brown-headed Cowbird in Southern Rockies / Colorado Plateau. See the full index history below.

Brown-headed Cowbird In Southern Rockies / Colorado Plateau Population Forecast

If the recent trend holds, Brown-headed Cowbird in Southern Rockies / Colorado Plateau is projected to rise about 37% by 2029 — from 2.5 in 2024 to a central estimate of 3.4 (95% range 0.17–6.6). A 5-year backtest shows a typical error of ±75.1%, with 100% of held-out values landing inside the 95% band.

+37%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 →
3.4Projected 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 →
0.17–6.695% 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 →
±75.1%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 Southern Rockies / Colorado Plateau is projected to rise about 37% by 2029 — from 2.5 in 2024 to a central estimate of 3.4 (95% range 0.17–6.6). A 5-year backtest shows a typical error of ±75.1%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20253.50.256.7
20263.40.236.7
20273.40.216.6
20283.40.196.6
20293.40.176.6

Routes In Southern Rockies / Colorado Plateau

Routes recording Brown-headed Cowbird in Southern Rockies / Colorado Plateau.
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 →
FalfaCOLORADO292024
DoloresCOLORADO261987
Ragged Mtn.COLORADO202019
AztecNEW-MEXICO181989
Douglas PassCOLORADO172024
Pleasant ViewCOLORADO172021
Pinos CreekCOLORADO151990
CapulinNEW-MEXICO151993
Pagosa SpgsCOLORADO141982
PasturaNEW-MEXICO142016
BeckUTAH131987
YampaCOLORADO122023
GuffeyCOLORADO122024
Yellowjacket PassCOLORADO122024
Wellington 2UTAH122011
AlamosaCOLORADO112024
AspenCOLORADO102024
FruitaCOLORADO102007
TarryallCOLORADO102023
WalsenburgCOLORADO102024
Claunch 2NEW-MEXICO102024
The GapARIZONA91976
AngoraCOLORADO82024
Stillwater PassCOLORADO82009
Animas 2COLORADO82018

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