BirdAnalyst
Species · Idaho · BBS 2025 Release · 1966–2024

Tree Swallow Population Trend in Idaho

All statesAerial insectivores

Tree Swallow in Idaho has risen sharply: up 68% on the route-weighted index since 1970.

+68%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 →
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 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 risen sharply in Idaho: up 68% 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 rise about 110% by 2029 — from 1.3 in 2024 to a central estimate of 2.8 (95% range 0.00–10). A 5-year backtest shows a typical error of ±38.6%, with 100% of held-out values landing inside the 95% band.

+110%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 →
2.8Projected 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 →
0.00–1095% 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 →
±38.6%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 rise about 110% by 2029 — from 1.3 in 2024 to a central estimate of 2.8 (95% range 0.00–10). A 5-year backtest shows a typical error of ±38.6%, with 100% 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 →
20252.90.0011
20262.90.0010
20272.90.0010
20282.80.0010
20292.80.0010

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
Cascade7119841968
Cabarton2620231985
Nezperce1620071968
Centerville1520191973
Daniels Res1520071988
Naples1220231972
Magic Mtn1220241987
Sawtooth Cty820141988
Challis620241977
Sawtooth City 2620232015
Bates620231988
Dougal Res520211989
Nezperce Nf519921992
Cape Horn420241988
Baldy Mountain420162013
Golden320161987
Alturas319861985
Almo320231991
Preston320171988
Blackft Res220181984
Mivoden220221977
Avery220162006
Lolo Pass220191992
Baker220241974

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 2026-05-22.