BirdAnalyst
Species · Maryland · BBS 2025 Release · 1966–2024

Blackburnian Warbler Population Trend in Maryland

All statesForest birds

Blackburnian Warbler in Maryland has surged: up 198% on the route-weighted index since 1968.

+198%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 →
6Routes 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 →
53YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Blackburnian 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 →

Blackburnian Warbler has surged in Maryland: up 198% on the route-weighted index since 1968.

Blackburnian Warbler Population Forecast in Maryland

If the recent trend holds, Blackburnian Warbler in Maryland is projected to fall about 22% by 2029 — from 0.17 in 2024 to a central estimate of 0.13 (95% range 0.04–0.22). A 5-year backtest shows a typical error of ±36.8%, with 80% of held-out values landing inside the 95% band.

-22%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 →
0.13Projected 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 →
0.04–0.2295% 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 →
±36.8%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, Blackburnian Warbler in Maryland is projected to fall about 22% by 2029 — from 0.17 in 2024 to a central estimate of 0.13 (95% range 0.04–0.22). A 5-year backtest shows a typical error of ±36.8%, with 80% 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 →
20250.120.040.21
20260.130.040.21
20270.130.040.21
20280.130.040.22
20290.130.040.22

Blackburnian Warbler Survey Routes in Maryland

Routes recording Blackburnian 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 →
Finzel520242000
Jennings220241997
Floyd120151966
Vindex120181966
Upper Xrds119711971
Steyer120072007

Blackburnian Warbler Population Trend in Other States

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

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