BirdAnalyst
Species · BCR 2 · BBS 2026 Release · 1966–2025

Tree Swallow In BCR 2

All regionsBCR 2Aerial insectivores

Tree Swallow in BCR 2 has increased: up 39% on the route-weighted index since 1986.

+39%Since 1986TrendPercent 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 →
22Routes 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 →
41YearsYears 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 →

No notable trend signals for Tree Swallow in BCR 2. See the full index history below.

Tree Swallow In BCR 2 Population Forecast

If the recent trend holds, Tree Swallow in BCR 2 is projected to rise about 17% by 2030 — from 5.2 in 2025 to a central estimate of 6.1 (95% range 0.00–14). A 5-year backtest shows a typical error of ±78%, with 100% of held-out values landing inside the 95% band.

+17%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 →
6.1Projected 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 →
0.00–1495% 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 →
±78%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 BCR 2 is projected to rise about 17% by 2030 — from 5.2 in 2025 to a central estimate of 6.1 (95% range 0.00–14). A 5-year backtest shows a typical error of ±78%, with 100% of held-out values landing inside the 95% band.19842030
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 →
20266.00.0014
20276.00.0014
20286.00.0014
20296.00.0014
20306.10.0014

Routes In BCR 2

Routes recording Tree Swallow in BCR 2.
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 →
Togiak RiverALASKA912005
TupuknukALASKA551995
Kanektok RivALASKA542005
DillinghamALASKA372019
King SalmonALASKA192025
Gweek RiverALASKA152002
Goodnews BayALASKA122005
Dillingham (Short)ALASKA91984
Katmai N.P.ALASKA52025
Cold BayALASKA52025
Kotzebue (Short)ALASKA51986
Salmon LakeALASKA42024
St. Mary'SALASKA42012
ChiniakALASKA32024
Selawik (Short)ALASKA31987
Cape NomeALASKA22023
NomeALASKA22022
KotzebueALASKA22025
Kugarak (Short)ALASKA21986
Cold Bay (Short)ALASKA21991
KodiakALASKA11984
Kodiak 2ALASKA12006

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