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Species · Maryland · BBS 2025 Release · 1966–2024

Carolina Wren Population Trend in Maryland

All statesForest birds

Carolina Wren in Maryland has surged: up 11× on the route-weighted index since 1968.

11×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 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 11× 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 fall about 27% by 2029 — from 39 in 2024 to a central estimate of 28 (95% range 19–38). A 5-year backtest shows a typical error of ±30.1%, with 60% of held-out values landing inside the 95% band.

-27%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 →
28Projected 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 →
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 →
±30.1%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, Carolina Wren in Maryland is projected to fall about 27% by 2029 — from 39 in 2024 to a central estimate of 28 (95% range 19–38). A 5-year backtest shows a typical error of ±30.1%, with 60% 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 →
2025271736
2026271737
2027271837
2028281837
2029281938

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 →
Island Creek10920241991
Cokesbury10220241966
Earlton9620242014
Honga6620241966
Madison6320241966
Forest Grove6320232011
Davidsnville6320241982
Ijamsville6220241986
Olney6120241967
Williamsport6020241966
Wheaton6020241990
Millington5120241966
Piney Neck5120241966
Walnut4820241999
Madonna4720222009
La Plata4620091966
Jessup4620242013
Emmitsburg4420241966
Pomonkey4420241966
Furnace Town4020242015
Nottingham4020242005
Warfieldsbrg3720241966
Beltsville3720121966
Hughesville3720241967
Newark3720241966

Carolina Wren Population Trend in Other States

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

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