BirdAnalyst
Species · New Jersey · BBS 2025 Release · 1966–2024

Tree Swallow Population Trend in New Jersey

All statesAerial insectivores

Tree Swallow in New Jersey has increased: up 40% on the route-weighted index since 1968.

+40%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 →
39Routes In StateSurvey 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 Tree Swallow Trends in New JerseyNotable 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 Jersey. See the full index history below.

Tree Swallow Population Forecast in New Jersey

If the recent trend holds, Tree Swallow in New Jersey is projected to rise about 84% by 2029 — from 2.1 in 2024 to a central estimate of 3.9 (95% range 1.3–6.4). A 5-year backtest shows a typical error of ±108%, with 80% of held-out values landing inside the 95% band.

+84%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 →
3.9Projected 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 →
1.3–6.495% 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 →
±108%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 Jersey is projected to rise about 84% by 2029 — from 2.1 in 2024 to a central estimate of 3.9 (95% range 1.3–6.4). A 5-year backtest shows a typical error of ±108%, with 80% 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 →
20253.71.16.2
20263.71.26.3
20273.81.26.3
20283.81.36.4
20293.91.36.4

Tree Swallow Survey Routes in New Jersey

Routes recording Tree Swallow in New Jersey.
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 →
Winslow820241990
New Bedford720241969
Deepwater519711969
Holmansville520091990
Bennett Mill 2520242016
Midvale420161967
Dover420221993
Woodbury Hgt320242006
Toms River320241967
Bloomsbury320161969
Gillette320241989
Keyport320191990
Roosevelt320211992
Friendship320241979
Greenwich220241966
Six Points220241978
Pottersville220231979
Ocean City220211979
Villas219811980
Mt Misery219881987
Pedricktown 2220242014
Cape May Ch220132001
Spraguetown 3220212021
Croton 2220232008
Albion120211990

Tree Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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