BirdAnalyst
Species · BCR 28 · BBS 2026 Release · 1966–2025

Tree Swallow In Appalachian Mountains

All regionsAppalachian MountainsAerial insectivores

Tree Swallow in Appalachian Mountains has surged: up 229% on the route-weighted index since 1968.

+229%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 →
340Routes 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 Appalachian Mountains: up 228% on the route-weighted index since 1968.

Tree Swallow In Appalachian Mountains Population Forecast

If the recent trend holds, Tree Swallow in Appalachian Mountains is projected to rise about 53% by 2030 — from 2.9 in 2025 to a central estimate of 4.5 (95% range 3.1–5.9). A 5-year backtest shows a typical error of ±61.7%, with 0% of held-out values landing inside the 95% band.

+53%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 →
4.5Projected 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 →
3.1–5.995% 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 →
±61.7%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 Appalachian Mountains is projected to rise about 53% by 2030 — from 2.9 in 2025 to a central estimate of 4.5 (95% range 3.1–5.9). A 5-year backtest shows a typical error of ±61.7%, with 0% 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 →
20264.32.85.7
20274.32.95.8
20284.43.05.8
20294.43.05.9
20304.53.15.9

Routes In Appalachian Mountains

Routes recording Tree Swallow in Appalachian Mountains.
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 →
RydePENNSYLVANIA272005
McdonoughNEW-YORK262017
SmithsburgMARYLAND252013
DurhamNEW-YORK251976
ToddNORTH-CAROLINA242025
S BerneNEW-YORK212013
HanoverWEST-VIRGINIA212025
SwainNEW-YORK202007
BetulaPENNSYLVANIA202022
GuntersvilleALABAMA192017
FontanaNORTH-CAROLINA182025
Brunnerville 2PENNSYLVANIA172025
BirminghamOHIO152019
BlacksburgVIRGINIA152025
SturgillsNORTH-CAROLINA132025
HonesdalePENNSYLVANIA132025
Natural BridVIRGINIA132025
OneontaALABAMA122025
LisleNEW-YORK122022
Vestal CtrNEW-YORK122019
WyalusingPENNSYLVANIA122025
Iron Mtn.VIRGINIA122011
Amos MillGEORGIA112022
WestbrookvleNEW-YORK112019
Warwick 2NEW-YORK112013

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