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

Gadwall In Shortgrass Prairie

All regionsShortgrass PrairieWaterfowl

Gadwall in Shortgrass Prairie has fallen sharply: down 55% on the route-weighted index since 1970.

-55%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 →
43Routes 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 →
48YearsYears 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 →

Gadwall has fallen sharply in Shortgrass Prairie: down 55% on the route-weighted index since 1970.

Gadwall In Shortgrass Prairie Population Forecast

If the recent trend holds, Gadwall in Shortgrass Prairie is projected to stay roughly flat through 2029, near 0.11 (95% range 0.00–0.32). A 5-year backtest shows a typical error of ±128.6%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.11Projected 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 →
0.00–0.3295% 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 →
±128.6%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, Gadwall in Shortgrass Prairie is projected to stay roughly flat through 2029, near 0.11 (95% range 0.00–0.32). A 5-year backtest shows a typical error of ±128.6%, 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 →
20250.110.000.33
20260.110.000.33
20270.110.000.32
20280.110.000.32
20290.110.000.32

Routes In Shortgrass Prairie

Routes recording Gadwall 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 →
Last ChanceCOLORADO91974
PantexTEXAS82009
NeegrandeCOLORADO72018
GrenvilleNEW-MEXICO61979
Wildhorse LCOLORADO52023
Fort MorganCOLORADO52011
ClovisNEW-MEXICO52013
StonehamCOLORADO42021
HaswellCOLORADO42022
NunnCOLORADO42018
JulesburgCOLORADO42004
Wagon MoundNEW-MEXICO41973
MaxwellNEW-MEXICO42013
HudsonCOLORADO32021
FlemingCOLORADO21985
KiowaCOLORADO22018
BethuneCOLORADO22017
GroverCOLORADO22022
AmherstCOLORADO22018
Prospect ValCOLORADO21999
LimonCOLORADO22016
KarvalCOLORADO22016
Sheridan LakCOLORADO21995
PritchettCOLORADO22010
Arsenal 2COLORADO22022

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