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

California Gull In Shortgrass Prairie

All regionsShortgrass PrairieWetland birds

California Gull in Shortgrass Prairie has surged: up 13× on the route-weighted index since 1986.

13×Since 1986TrendPercent 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 →
6Routes 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 →
23YearsYears 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 increasecomputed 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 →

California Gull has surged in Shortgrass Prairie: up 13× on the route-weighted index since 1986.

Forecast

If the recent trend holds, California Gull in Shortgrass Prairie is projected to rise about 265% by 2029 — from 0.11 in 2024 to a central estimate of 0.39 (95% range 0.00–1.2). A 5-year backtest shows a typical error of ±507.4%, with 80% of held-out values landing inside the 95% band.

+265%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 →
0.39Projected 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 →
0.00–1.295% 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 →
±507.4%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, California Gull in Shortgrass Prairie is projected to rise about 265% by 2029 — from 0.11 in 2024 to a central estimate of 0.39 (95% range 0.00–1.2). A 5-year backtest shows a typical error of ±507.4%, with 80% of held-out values landing inside the 95% band.19812029
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 →
20250.380.001.2
20260.380.001.2
20270.390.001.2
20280.390.001.2
20290.390.001.2

Routes In Shortgrass Prairie

Routes recording California Gull 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 →
BriggsdaleCOLORADO952023
HudsonCOLORADO92024
Fort MorganCOLORADO42000
YoderWYOMING42012
JulesburgCOLORADO32002
Doyle BridgeCOLORADO11994

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