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

Northern Rough-winged Swallow Population Trend in Delaware

All statesAerial insectivores

Northern Rough-winged Swallow in Delaware has fallen sharply: down 60% on the route-weighted index since 1968.

-60%Since 1968
13Routes In State
50Years

Notable Northern Rough-winged Swallow Trends in Delaware

long arc declinecomputed index

Northern Rough-winged Swallow has fallen sharply in Delaware: down 60% on the route-weighted index since 1968.

Northern Rough-winged Swallow Population Forecast in Delaware

If the recent trend holds, Northern Rough-winged Swallow in Delaware is projected to stay roughly flat through 2027, near 0.43 (95% range 0.00–2.1). A 5-year backtest shows a typical error of ±123.8%, with 100% of held-out values landing inside the 95% band.

+8%Change by 2027
0.43Projected 2027 index
0.00–2.195% range
±123.8%Backtest error
19662027
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
20230.490.002.2
20240.480.002.2
20250.460.002.2
20260.450.002.1
20270.430.002.1

Northern Rough-winged Swallow Survey Routes in Delaware

Routes recording Northern Rough-winged Swallow in Delaware.
Lowes Xrds419781975
Mt Pleasant220061977
Wilmington220101987
Harrington220221977
Frederica220121970
Frankford219961968
Holleyville220031968
Milton220061967
Blackbird219941994
Georgetown219921992
Dover119851985
Bethany Bch119901966
Pepperbox119981998

Northern Rough-winged 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.