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Species · Maryland · BBS 2025 Release · 1966–2024

Chestnut-sided Warbler Population Trend in Maryland

All statesForest birds

Chestnut-sided Warbler in Maryland has surged: up 114% on the route-weighted index since 1968.

+114%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 →
13Routes 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 Chestnut-sided Warbler 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 →

Chestnut-sided Warbler has surged in Maryland: up 114% on the route-weighted index since 1968.

Chestnut-sided Warbler Population Forecast in Maryland

If the recent trend holds, Chestnut-sided Warbler in Maryland is projected to rise about 20% by 2029 — from 1.3 in 2024 to a central estimate of 1.6 (95% range 1.1–2.1). A 5-year backtest shows a typical error of ±12.7%, with 100% of held-out values landing inside the 95% band.

+20%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 →
1.6Projected 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 →
1.1–2.195% 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 →
±12.7%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, Chestnut-sided Warbler in Maryland is projected to rise about 20% by 2029 — from 1.3 in 2024 to a central estimate of 1.6 (95% range 1.1–2.1). A 5-year backtest shows a typical error of ±12.7%, 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 →
20251.50.982.0
20261.51.02.0
20271.51.02.0
20281.51.12.0
20291.61.12.1

Chestnut-sided Warbler Survey Routes in Maryland

Routes recording Chestnut-sided Warbler 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 →
Finzel2720241995
Jennings1720241995
Accident820171992
Vindex520241966
Accident 2320242018
Floyd220241966
Mt Nebo219911969
Wolfsville219681968
Oldtown120211991
Fowblesburg119691969
Eklo119671967
Steyer120241996
Piney Grove119961996

Chestnut-sided Warbler Population Trend in Other States

alabamaarkansascoloradoconnecticutgeorgiaillinoisindianaiowakansaskentuckymainemassachusettsmichiganminnesotanevadanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiopennsylvaniarhode-islandtennesseevermontvirginiawest-virginiawisconsinwyoming

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