BirdAnalyst
Species · BCR 9 · BBS 2026 Release · 1966–2025

American Bittern In Great Basin

All regionsGreat BasinWetland birds

American Bittern in Great Basin has declined: down 37% on the route-weighted index since 1972.

-37%Since 1972TrendPercent 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 →
54YearsYears 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 American Bittern in Great Basin. See the full index history below.

American Bittern In Great Basin Population Forecast

If the recent trend holds, American Bittern in Great Basin is projected to stay roughly flat through 2030, near 0.07 (95% range 0.00–0.22). A 5-year backtest shows a typical error of ±117.7%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.07Projected 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 →
0.00–0.2295% 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 →
±117.7%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, American Bittern in Great Basin is projected to stay roughly flat through 2030, near 0.07 (95% range 0.00–0.22). A 5-year backtest shows a typical error of ±117.7%, with 100% of held-out values landing inside the 95% band.19702030
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 →
20260.070.000.22
20270.070.000.22
20280.070.000.22
20290.070.000.22
20300.070.000.22

Routes In Great Basin

Routes recording American Bittern in Great Basin.
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 →
Virgin CreekNEVADA52018
MerrillOREGON42013
Warner VallyOREGON41999
DorrisCALIFORNIA32019
MacdoelCALIFORNIA32017
Fish LakeOREGON32025
Turnbull NwrWASHINGTON32016
NubieberCALIFORNIA22007
Honey LakeCALIFORNIA22025
Davis CreekCALIFORNIA21999
EurekaNEVADA22000
GardnervilleNEVADA22006
BlyOREGON22001
PromontoryUTAH22006
CallaoUTAH22024
Moses LakeWASHINGTON22004
PotholesWASHINGTON22019
LikelyCALIFORNIA12024
Crowley LakeCALIFORNIA11972
CedarvilleCALIFORNIA12017
TionestaCALIFORNIA12019
Crowder FlatCALIFORNIA12007
SquirrelIDAHO11971
PicaboIDAHO11990
Mud LakeIDAHO11988

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