BirdAnalyst
Species · BCR 15 · BBS 2025 Release · 1966–2024

Swainson's Thrush In Sierra Nevada

All regionsSierra NevadaForest birds

Swainson's Thrush in Sierra Nevada has surged: up 90% on the route-weighted index since 1974.

+90%Since 1974
16Routes In Region
38Years

Notable Signals

long arc increasecomputed index

Swainson's Thrush has surged in Sierra Nevada: up 90% on the route-weighted index since 1974.

Forecast

If the recent trend holds, Swainson's Thrush in Sierra Nevada is projected to fall about 41% by 2029 — from 0.42 in 2024 to a central estimate of 0.25 (95% range 0.00–0.53). A 5-year backtest shows a typical error of ±68.1%, with 40% of held-out values landing inside the 95% band.

-41%Change by 2029
0.25Projected 2029 index
0.00–0.5395% range
±68.1%Backtest error
19712029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected index95% low95% high
20250.240.000.52
20260.240.000.52
20270.240.000.53
20280.250.000.53
20290.250.000.53

Routes In Sierra Nevada

Routes recording Swainson's Thrush in Sierra Nevada.
LumberyardCALIFORNIA61989
Meadow ValleyCALIFORNIA52024
PlacervilleCALIFORNIA32024
Lassen ParkCALIFORNIA21979
WestvilleCALIFORNIA22021
Greenhorn MtCALIFORNIA21974
Silver CityCALIFORNIA22002
DardanelleCALIFORNIA11978
JohnsvilleCALIFORNIA12015
WoodfordsCALIFORNIA11983
Kings CanyonCALIFORNIA11989
Tuolumne GroveCALIFORNIA11994
Butte MeadowCALIFORNIA11995
RivertonCALIFORNIA12017
PaxtonCALIFORNIA12019
Pollock PinesCALIFORNIA12019

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