BirdAnalyst
Species · BCR 14 · BBS 2025 Release · 1966–2024

Tree Swallow In Atlantic Northern Forest

All regionsAtlantic Northern ForestAerial insectivores

Tree Swallow in Atlantic Northern Forest has fallen sharply: down 73% on the route-weighted index since 1968.

-73%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 →
155Routes 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 →
58YearsYears 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 declinecomputed 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 fallen sharply in Atlantic Northern Forest: down 73% on the route-weighted index since 1968.

Tree Swallow In Atlantic Northern Forest Population Forecast

If the recent trend holds, Tree Swallow in Atlantic Northern Forest is projected to fall about 71% by 2029 — from 3.9 in 2024 to a central estimate of 1.1 (95% range 0.00–6.2). A 5-year backtest shows a typical error of ±18.1%, with 100% of held-out values landing inside the 95% band.

-71%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 →
1.1Projected 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 →
0.00–6.295% 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 →
±18.1%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 Atlantic Northern Forest is projected to fall about 71% by 2029 — from 3.9 in 2024 to a central estimate of 1.1 (95% range 0.00–6.2). A 5-year backtest shows a typical error of ±18.1%, with 100% of held-out values landing inside the 95% band.19662029
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 →
20252.40.007.5
20262.10.007.2
20271.80.006.9
20281.50.006.6
20291.10.006.2

Routes In Atlantic Northern Forest

Routes recording Tree Swallow in Atlantic Northern Forest.
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 →
NorthfieldMAINE451981
BentonMAINE441980
ManchesterMAINE391995
Crawford NotNEW-HAMPSHIRE321975
WaiteMAINE241977
MedwayMAINE202018
Hope FallsNEW-YORK201995
East HavenVERMONT192024
Moose RiverMAINE182008
Cummington 2MASSACHUSETTS182024
WatervilleVERMONT161980
ChesterfieldMASSACHUSETTS152024
St DavidMAINE142005
CheshireMASSACHUSETTS141994
Forest StaMAINE132000
HardwickVERMONT132024
CarrabassettMAINE122023
BoundaryMAINE122016
Dexter LakeNEW-YORK121975
Otisfield GrMAINE112015
WarrenMAINE111990
CummingtonMASSACHUSETTS112014
WalpoleNEW-HAMPSHIRE112024
LandgroveVERMONT112024
GreensboroVERMONT112024

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.