BirdAnalyst
Species · Idaho · BBS 2026 Release · 1966–2025

Tree Swallow Population Trend in Idaho

All statesAerial insectivores

Tree Swallow in Idaho has surged: up 101% on the route-weighted index since 1970.

+101%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 →
53Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Tree Swallow Trends in IdahoNotable 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 Idaho: up 101% on the route-weighted index since 1970.

Tree Swallow Population Forecast in Idaho

If the recent trend holds, Tree Swallow in Idaho is projected to fall about 27% by 2030 — from 3.9 in 2025 to a central estimate of 2.9 (95% range 0.00–10). A 5-year backtest shows a typical error of ±19.9%, with 100% of held-out values landing inside the 95% band.

-27%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 →
2.9Projected 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 →
0.00–1095% 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 →
±19.9%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 Idaho is projected to fall about 27% by 2030 — from 3.9 in 2025 to a central estimate of 2.9 (95% range 0.00–10). A 5-year backtest shows a typical error of ±19.9%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20263.00.0011
20273.00.0010
20283.00.0010
20292.90.0010
20302.90.0010

Tree Swallow Survey Routes in Idaho

Routes recording Tree Swallow in Idaho.
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 →
Henry9319831973
Naples8920251972
Cascade7119841968
Cabarton1820241985
Nezperce1620071968
Daniels Res1520071988
Magic Mtn1220251987
Sawtooth Cty820141988
Cape Horn720251988
Centerville720251973
Challis620241977
Coolin620251986
Bates620231988
Dougal Res520211989
Nezperce Nf519921992
Baldy Mountain420162013
Avery320252006
Golden320161987
Alturas319861985
Rochat Divde320251994
Featherville320251989
Almo320231991
Preston320171988
Blackft Res220181984
Mivoden220251977

Tree Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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