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

Tree Swallow In Sierra Nevada

All regionsSierra NevadaAerial insectivores

Tree Swallow in Sierra Nevada has surged: up 94% on the route-weighted index since 1970.

+94%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 →
30Routes 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 →
56YearsYears 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 →

Tree Swallow has surged in Sierra Nevada: up 94% on the route-weighted index since 1970.

Tree Swallow In Sierra Nevada Population Forecast

If the recent trend holds, Tree Swallow in Sierra Nevada is projected to rise about 191% by 2029 — from 1.2 in 2024 to a central estimate of 3.4 (95% range 1.5–5.2). A 5-year backtest shows a typical error of ±93.2%, with 60% of held-out values landing inside the 95% band.

+191%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 →
3.4Projected 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 →
1.5–5.295% 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 →
±93.2%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, Tree Swallow in Sierra Nevada is projected to rise about 191% by 2029 — from 1.2 in 2024 to a central estimate of 3.4 (95% range 1.5–5.2). A 5-year backtest shows a typical error of ±93.2%, with 60% 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 →
20253.21.35.1
20263.31.45.1
20273.31.45.2
20283.31.55.2
20293.41.55.2

Routes In Sierra Nevada

Routes recording Tree Swallow 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 →
Bass LakeCALIFORNIA112018
SattleyCALIFORNIA72014
PaxtonCALIFORNIA72024
KernvilleCALIFORNIA72008
JohnsvilleCALIFORNIA52023
Meadow ValleyCALIFORNIA52024
Last ChanceCALIFORNIA52019
GoumazCALIFORNIA42011
WawonaCALIFORNIA42021
WoodfordsCALIFORNIA32024
GeneseeCALIFORNIA32024
DownievilleCALIFORNIA32024
ChilcootCALIFORNIA31998
Cottage SpgsCALIFORNIA21975
DardanelleCALIFORNIA21993
Greenhorn MtCALIFORNIA22008
Silver CityCALIFORNIA22013
Kings CanyonCALIFORNIA21982
Hat CreekCALIFORNIA22017
Chaos CraterCALIFORNIA22019
CrestviewCALIFORNIA21998
Lassen ParkCALIFORNIA11989
Eagle LakeCALIFORNIA12024
Tuolumne GroveCALIFORNIA12000
Butte MeadowCALIFORNIA12014

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