BirdAnalyst
Species · BCR 15 · BBS 2026 Release · 1966–2025

Vesper Sparrow In Sierra Nevada

All regionsSierra NevadaGrassland birds

Vesper Sparrow in Sierra Nevada has risen sharply: up 65% on the route-weighted index since 1973.

+65%Since 1973TrendPercent 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 →
11Routes 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 →
52YearsYears 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 →

Vesper Sparrow has risen sharply in Sierra Nevada: up 65% on the route-weighted index since 1973.

Vesper Sparrow In Sierra Nevada Population Forecast

If the recent trend holds, Vesper Sparrow in Sierra Nevada is projected to stay roughly flat through 2030, near 1.7 (95% range 0.03–3.4). A 5-year backtest shows a typical error of ±238.4%, with 60% of held-out values landing inside the 95% band.

+5%Change 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 →
1.7Projected 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 →
0.03–3.495% 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 →
±238.4%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, Vesper Sparrow in Sierra Nevada is projected to stay roughly flat through 2030, near 1.7 (95% range 0.03–3.4). A 5-year backtest shows a typical error of ±238.4%, with 60% 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 →
20261.70.013.3
20271.70.013.3
20281.70.023.4
20291.70.023.4
20301.70.033.4

Routes In Sierra Nevada

Routes recording Vesper Sparrow in Sierra Nevada.
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 →
SattleyCALIFORNIA192025
GoumazCALIFORNIA182011
Last ChanceCALIFORNIA172019
Eagle LakeCALIFORNIA52025
Little TruckeeCALIFORNIA32025
LakeshoreCALIFORNIA22006
DardanelleCALIFORNIA12019
WoodfordsCALIFORNIA12025
RivertonCALIFORNIA11975
CrestviewCALIFORNIA12025
ChilcootCALIFORNIA12024

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