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Species · Maryland · BBS 2026 Release · 1966–2025

Canada Warbler Population Trend in Maryland

All statesForest birds

Canada Warbler in Maryland has fallen sharply: down 58% on the route-weighted index since 1968.

-58%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 →
7Routes 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 →
55YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Canada 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 declinecomputed 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 →

Canada Warbler has fallen sharply in Maryland: down 58% on the route-weighted index since 1968.

Canada Warbler Population Forecast in Maryland

If the recent trend holds, Canada Warbler in Maryland is projected to fall about 42% by 2030 — from 0.08 in 2025 to a central estimate of 0.05 (95% range 0.00–0.16). A 5-year backtest shows a typical error of ±75%, with 80% of held-out values landing inside the 95% band.

-42%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 →
0.05Projected 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 →
0.00–0.1695% 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 →
±75%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, Canada Warbler in Maryland is projected to fall about 42% by 2030 — from 0.08 in 2025 to a central estimate of 0.05 (95% range 0.00–0.16). A 5-year backtest shows a typical error of ±75%, with 80% 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 →
20260.050.000.16
20270.050.000.16
20280.050.000.16
20290.050.000.16
20300.050.000.16

Canada Warbler Survey Routes in Maryland

Routes recording Canada 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 →
Floyd220251966
Mt Nebo119911969
Vindex120041966
Oldtown120242024
Accident120171993
Accident 2120242018
Jennings120251995

Canada Warbler Population Trend in Other States

connecticutgeorgiaindianamainemassachusettsmichiganminnesotanew-hampshirenew-jerseynew-yorknorth-carolinaohiopennsylvaniarhode-islandtennesseevermontvirginiawest-virginiawisconsin

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