BirdAnalyst
Species · BCR 18 · BBS 2025 Release · 1966–2024

Brewer's Blackbird In Shortgrass Prairie

All regionsShortgrass PrairieGeneralists

Brewer's Blackbird in Shortgrass Prairie has collapsed: down 88% on the route-weighted index since 1970.

-88%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 →
61Routes 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 →
55YearsYears 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 →

Brewer's Blackbird has collapsed in Shortgrass Prairie: down 88% on the route-weighted index since 1970.

Brewer's Blackbird In Shortgrass Prairie Population Forecast

If the recent trend holds, Brewer's Blackbird in Shortgrass Prairie is projected to fall about 31% by 2029 — from 0.29 in 2024 to a central estimate of 0.20 (95% range 0.00–4.0). A 5-year backtest shows a typical error of ±37.2%, with 100% of held-out values landing inside the 95% band.

-31%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 →
0.20Projected 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 →
0.00–4.095% 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 →
±37.2%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, Brewer's Blackbird in Shortgrass Prairie is projected to fall about 31% by 2029 — from 0.29 in 2024 to a central estimate of 0.20 (95% range 0.00–4.0). A 5-year backtest shows a typical error of ±37.2%, 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 →
20250.460.004.2
20260.390.004.1
20270.330.004.1
20280.260.004.0
20290.200.004.0

Routes In Shortgrass Prairie

Routes recording Brewer's Blackbird in Shortgrass Prairie.
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 →
BriggsdaleCOLORADO352008
KiowaCOLORADO292018
BereaNEBRASKA182017
ElbertCOLORADO112024
Kiowa 2COLORADO102023
CrawfordNEBRASKA92019
Pine RidgeNEBRASKA82002
GilpinCOLORADO71984
BennettCOLORADO72017
Prospect ValCOLORADO62000
NeegrandeCOLORADO62019
NunnCOLORADO62006
Murray LakeNEBRASKA62024
Wagon MoundNEW-MEXICO61971
Cooley LakeNEW-MEXICO61976
PinneoCOLORADO51977
AbarrCOLORADO52023
Adams Co.COLORADO52022
VillegreenCOLORADO52000
HardestyOKLAHOMA51988
YoderWYOMING52023
Pine BluffWYOMING52023
Two ButtesCOLORADO42013
Wildhorse LCOLORADO42015
EdisonCOLORADO42024

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