BirdAnalyst
Species · Maryland · BBS 2026 Release · 1966–2025

Chimney Swift Population Trend in Maryland

All statesAerial insectivores

Chimney Swift in Maryland has declined: down 33% on the route-weighted index since 1968.

-33%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 →
59YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Chimney Swift 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 Chimney Swift in Maryland. See the full index history below.

Chimney Swift Population Forecast in Maryland

If the recent trend holds, Chimney Swift in Maryland is projected to fall about 12% by 2030 — from 9.2 in 2025 to a central estimate of 8.2 (95% range 4.2–12). A 5-year backtest shows a typical error of ±5.9%, with 100% of held-out values landing inside the 95% band.

-12%Change by 2030TrendPercent 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 →
8.2Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
4.2–1295% 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 →
±5.9%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, Chimney Swift in Maryland is projected to fall about 12% by 2030 — from 9.2 in 2025 to a central estimate of 8.2 (95% range 4.2–12). A 5-year backtest shows a typical error of ±5.9%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20268.44.412
20278.44.412
20288.34.312
20298.24.212
20308.24.212

Chimney Swift Survey Routes in Maryland

Routes recording Chimney Swift 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 →
Jones5519941966
Williamsport5220251966
Ijamsville4720251986
Largo4219811966
Harmony4220171966
Island Creek4220251991
Snow Hill3519761966
Eklo2720181966
Silver Spg2519891966
Beltsville2520121966
Emmitsburg2320251966
Forest Grove1920232011
Cokesbury1720251966
Pr Frederick1620251991
Fair Hill1519961992
Olney1420251966
Pt Republic1419891966
Melitota1420251966
Norwood1320121966
Walnut1320241999
La Plata1220091966
Golden Hill1220251966
Sinepuxent1219781966
Bald Friar1219961992
Honga1120251967

Chimney Swift Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.