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Species · Maryland · BBS 2025 Release · 1966–2024

Barn Swallow Population Trend in Maryland

All statesAerial insectivores

Barn Swallow in Maryland has edged down: down 23% on the route-weighted index since 1968.

-23%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 →
76Routes 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 Barn Swallow Trends in MarylandNotable 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 Barn Swallow in Maryland. See the full index history below.

Barn Swallow Population Forecast in Maryland

If the recent trend holds, Barn Swallow in Maryland is projected to stay roughly flat through 2029, near 16 (95% range 11–22). A 5-year backtest shows a typical error of ±14.9%, with 100% of held-out values landing inside the 95% band.

+6%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 →
16Projected 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 →
11–2295% 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 →
±14.9%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, Barn Swallow in Maryland is projected to stay roughly flat through 2029, near 16 (95% range 11–22). A 5-year backtest shows a typical error of ±14.9%, 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 →
2025171122
2026171122
2027171122
2028161122
2029161122

Barn Swallow Survey Routes in Maryland

Routes recording Barn Swallow in Maryland.
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 →
Harmony9820171966
Madonna9820222009
Cokesbury8520241966
Emmitsburg5520241966
Earlton5120242014
Snow Hill4919761966
Eklo4320181966
Jennings4220241995
Mardela3520191966
Williamsport3420241966
Bachman Mill3320241966
Sinepuxent3319781966
Mt Nebo3119911969
Olney2920241966
Pleasant Val2520241966
Smithsburg2320141966
Walnut2320241999
Finzel2220241995
La Plata2120091966
Easton2120211966
Ijamsville1920241986
Fowblesburg1820171966
Honga1820241966
Wolfsville1720241966
Accident1720171992

Barn Swallow Population Trend in Other States

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

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