BirdAnalyst
Species · Delaware · BBS 2025 Release · 1966–2024

Tree Swallow Population Trend in Delaware

All statesAerial insectivores

Tree Swallow in Delaware has surged: up 729% on the route-weighted index since 1968.

+729%Since 1968
17Routes In State
57Years

Notable Tree Swallow Trends in Delaware

long arc increasecomputed index

Tree Swallow has surged in Delaware: up 729% on the route-weighted index since 1968.

Tree Swallow Population Forecast in Delaware

If the recent trend holds, Tree Swallow in Delaware is projected to rise about 81% by 2029 — from 4.2 in 2024 to a central estimate of 7.6 (95% range 3.7–11). A 5-year backtest shows a typical error of ±72.8%, with 40% of held-out values landing inside the 95% band.

+81%Change by 2029
7.6Projected 2029 index
3.7–1195% range
±72.8%Backtest error
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 index95% low95% high
20257.13.211
20267.23.411
20277.33.511
20287.53.611
20297.63.711

Tree Swallow Survey Routes in Delaware

Routes recording Tree Swallow in Delaware.
Wilmington1820141967
Georgetown1820221995
Frederica1020141994
Harrington820241966
Blackbird620241994
Milton520161974
Mt Pleasant420191971
Holleyville420031975
Holleyville 2420242007
Bethany Bch319901966
Millsboro320172017
Pepperbox 2320242018
Dover219871967
Lowes Xrds219911969
Pepperbox220161998
Milton 2220172017
Frankford120121969

Tree Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutfloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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