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Species · Maryland · BBS 2026 Release · 1966–2025

Carolina Wren Population Trend in Maryland

All statesForest birds

Carolina Wren in Maryland has surged: up 959% on the route-weighted index since 1968.

+959%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 Carolina Wren 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 →

Carolina Wren has surged in Maryland: up 959% on the route-weighted index since 1968.

Carolina Wren Population Forecast in Maryland

If the recent trend holds, Carolina Wren in Maryland is projected to rise about 12% by 2030 — from 25 in 2025 to a central estimate of 29 (95% range 19–38). A 5-year backtest shows a typical error of ±25.4%, with 60% 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 →
29Projected 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 →
19–3895% 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 →
±25.4%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, Carolina Wren in Maryland is projected to rise about 12% by 2030 — from 25 in 2025 to a central estimate of 29 (95% range 19–38). A 5-year backtest shows a typical error of ±25.4%, with 60% 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 →
2026271736
2027271837
2028281837
2029281938
2030291938

Carolina Wren Survey Routes in Maryland

Routes recording Carolina Wren 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 →
Earlton9620242014
Forest Grove6320232011
Island Creek6220251991
Cokesbury6020251966
Olney5920251967
Ijamsville5720251986
Honga5520251966
Walnut4820241999
Williamsport4720251966
Emmitsburg4720251966
Madonna4720222009
La Plata4620091966
Warfieldsbrg4020251966
Wheaton3920251990
Beltsville3720121966
Millington3420251966
Pomonkey3320251966
Madison3320251966
Berlin3320251980
Pomfret3120241966
Eklo3020181969
Snow Hill2919761966
Piney Neck2720251966
Smithsburg2620141972
Newark2620251966

Carolina Wren Population Trend in Other States

alabamaarkansasconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemassachusettsmichiganminnesotamississippimissourinebraskanew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseetexasvermontvirginiawest-virginiawisconsin

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