BirdAnalyst
Species · BCR 30 · BBS 2025 Release · 1966–2024

Tree Swallow In New England / Mid-Atlantic Coast

All regionsNew England / Mid-Atlantic CoastAerial insectivores

Tree Swallow in New England / Mid-Atlantic Coast has edged up: up 17% on the route-weighted index since 1968.

+17%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 →
153Routes 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 →

No notable trend signals for Tree Swallow in New England / Mid-Atlantic Coast. See the full index history below.

Tree Swallow In New England / Mid-Atlantic Coast Population Forecast

If the recent trend holds, Tree Swallow in New England / Mid-Atlantic Coast is projected to stay roughly flat through 2029, near 4.3 (95% range 2.9–5.6). A 5-year backtest shows a typical error of ±10.9%, with 100% of held-out values landing inside the 95% band.

+7%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 →
4.3Projected 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 →
2.9–5.695% 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 →
±10.9%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 New England / Mid-Atlantic Coast is projected to stay roughly flat through 2029, near 4.3 (95% range 2.9–5.6). A 5-year backtest shows a typical error of ±10.9%, 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 →
20254.22.85.5
20264.22.95.6
20274.22.95.6
20284.32.95.6
20294.32.95.6

Routes In New England / Mid-Atlantic Coast

Routes recording Tree Swallow in New England / Mid-Atlantic Coast.
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 →
MadisonMARYLAND292024
HongaMARYLAND252024
BrandonVIRGINIA252024
WilmingtonDELAWARE182014
GeorgetownDELAWARE182022
N. AndoverMASSACHUSETTS172024
WarrenCONNECTICUT132011
JessupMARYLAND132024
Cape CharlesVIRGINIA132018
MansfieldMASSACHUSETTS122024
MarionMASSACHUSETTS112024
BrentwoodNEW-HAMPSHIRE111997
Jones BeachNEW-YORK112013
FredericaDELAWARE102014
BrocktonMASSACHUSETTS102019
BelchertownMASSACHUSETTS102024
ShermanCONNECTICUT92019
Warren 2MASSACHUSETTS92024
Mid HaddamCONNECTICUT82024
HarringtonDELAWARE82024
S BarreMASSACHUSETTS82024
Gay HeadMASSACHUSETTS82023
WinslowNEW-JERSEY82024
WoodstockCONNECTICUT72007
WestbrookCONNECTICUT72024

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