BirdAnalyst
Species · BCR 22 · BBS 2026 Release · 1966–2025

Tree Swallow In Eastern Tallgrass Prairie

All regionsEastern Tallgrass PrairieAerial insectivores

Tree Swallow in Eastern Tallgrass Prairie has surged: up 15× on the route-weighted index since 1968.

15×Since 1968TrendPercent 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 →
250Routes 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 →
59YearsYears 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 Eastern Tallgrass Prairie: up 15× on the route-weighted index since 1968.

Tree Swallow In Eastern Tallgrass Prairie Population Forecast

If the recent trend holds, Tree Swallow in Eastern Tallgrass Prairie is projected to fall about 27% by 2030 — from 3.2 in 2025 to a central estimate of 2.3 (95% range 1.6–3.0). A 5-year backtest shows a typical error of ±30%, with 40% 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 →
2.3Projected 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 →
1.6–3.095% 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 →
±30%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 Eastern Tallgrass Prairie is projected to fall about 27% by 2030 — from 3.2 in 2025 to a central estimate of 2.3 (95% range 1.6–3.0). A 5-year backtest shows a typical error of ±30%, with 40% of held-out values landing inside the 95% band.19662030
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 →
20262.11.42.9
20272.21.42.9
20282.21.52.9
20292.31.53.0
20302.31.63.0

Routes In Eastern Tallgrass Prairie

Routes recording Tree Swallow in Eastern Tallgrass Prairie.
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 →
BryantIOWA2582025
LafayetteIOWA252025
Gretna 2NEBRASKA232023
MilroyINDIANA212025
MarionOHIO162023
SenecaILLINOIS132025
PittsburgKANSAS132012
House SpringsMISSOURI132025
GeneseoILLINOIS122025
FrankfortINDIANA122025
PrairieburgIOWA122025
West LibertyIOWA112007
StreatorILLINOIS102024
CaledoniaILLINOIS102025
KeithsburgILLINOIS102025
GridleyILLINOIS102024
MelroseIOWA102024
KunkleOHIO102024
WayneILLINOIS92025
Le RoyILLINOIS92025
JamestownINDIANA92019
HudsonIOWA92022
Kings CreekOHIO92015
KentonOHIO92025
GalvestonINDIANA82024

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