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

Chimney Swift Population Trend in Maryland

All statesAerial insectivores

Chimney Swift in Maryland has declined: down 35% on the route-weighted index since 1968.

-35%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 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 14% by 2029 — from 9.5 in 2024 to a central estimate of 8.2 (95% range 4.1–12). A 5-year backtest shows a typical error of ±8.1%, with 100% of held-out values landing inside the 95% band.

-14%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 →
8.2Projected 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 →
4.1–1295% 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 →
±8.1%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 14% by 2029 — from 9.5 in 2024 to a central estimate of 8.2 (95% range 4.1–12). A 5-year backtest shows a typical error of ±8.1%, 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 →
20258.44.412
20268.44.312
20278.34.312
20288.24.212
20298.24.112

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
Williamsport4820241966
Wheaton4320241990
Largo4219811966
Harmony4220171966
Island Creek3620241991
Snow Hill3519761966
Eklo2720181966
Ijamsville2720241986
Silver Spg2519891966
Beltsville2520121966
Forest Grove1920232011
Emmitsburg1820241966
Potomac Park1520241970
Olney1520241966
Fair Hill1519961992
Pt Republic1419891966
Pr Frederick1420241991
Norwood1320121966
Hughesville1320241966
Easton1320211966
Accident 21320242018
Walnut1320241999
Nottingham1320242005
Warfieldsbrg1220241966

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 2026-05-22.