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Species · Maryland · BBS 2026 Release · 1966–2025

Cliff Swallow Population Trend in Maryland

All statesAerial insectivores

Cliff Swallow in Maryland has surged: up 190% on the route-weighted index since 1969.

+190%Since 1969TrendPercent 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 →
21Routes 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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Cliff 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 →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Cliff Swallow has surged in Maryland: up 190% on the route-weighted index since 1969.

Cliff Swallow Population Forecast in Maryland

If the recent trend holds, Cliff Swallow in Maryland is projected to fall about 26% by 2030 — from 0.74 in 2025 to a central estimate of 0.55 (95% range 0.19–0.91). A 5-year backtest shows a typical error of ±176.5%, with 40% of held-out values landing inside the 95% band.

-26%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 →
0.55Projected 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 →
0.19–0.9195% 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 →
±176.5%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, Cliff Swallow in Maryland is projected to fall about 26% by 2030 — from 0.74 in 2025 to a central estimate of 0.55 (95% range 0.19–0.91). A 5-year backtest shows a typical error of ±176.5%, with 40% 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 →
20260.520.160.88
20270.530.170.89
20280.530.170.89
20290.540.180.90
20300.550.190.91

Cliff Swallow Survey Routes in Maryland

Routes recording Cliff 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 →
Finzel1520251997
Jennings1020251997
Eklo620171969
Mt Nebo419911970
Potomac Park320211973
Beltsville320101983
Floyd220211966
Vindex220171967
Williamsport220252008
Bachman Mill219751975
Pomfret220002000
Emmitsburg120252025
Olney120141991
Pleasant Val119661966
Fowblesburg120041983
Steyer120191996
Accident 2120212021
Accident120101995
Wheaton120142014
Ijamsville120192011
Davidsnville119951995

Cliff Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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