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Species · Maryland · BBS 2025 Release · 1966–2024

Blue-headed Vireo Population Trend in Maryland

All statesForest birds

Blue-headed Vireo in Maryland has surged: up 17× on the route-weighted index since 1968.

17×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 →
11Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Blue-headed Vireo 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 →

Blue-headed Vireo has surged in Maryland: up 17× on the route-weighted index since 1968.

Blue-headed Vireo Population Forecast in Maryland

If the recent trend holds, Blue-headed Vireo in Maryland is projected to fall about 20% by 2029 — from 0.79 in 2024 to a central estimate of 0.63 (95% range 0.40–0.85). A 5-year backtest shows a typical error of ±37.2%, with 20% 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 →
0.63Projected 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 →
0.40–0.8595% 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 →
±37.2%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, Blue-headed Vireo in Maryland is projected to fall about 20% by 2029 — from 0.79 in 2024 to a central estimate of 0.63 (95% range 0.40–0.85). A 5-year backtest shows a typical error of ±37.2%, with 20% 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 →
20250.580.360.81
20260.590.370.82
20270.600.380.83
20280.620.390.84
20290.630.400.85

Blue-headed Vireo Survey Routes in Maryland

Routes recording Blue-headed Vireo 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 →
Finzel1220241995
Jennings1020241995
Vindex320241966
Steyer320241996
Oldtown220241982
Accident220171993
Accident 2220242018
Floyd120241966
Mt Nebo119911969
Green Ridge120231995
Piney Grove120212014

Blue-headed Vireo Population Trend in Other States

alabamaconnecticutgeorgiakentuckymainemassachusettsmichiganminnesotanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiopennsylvaniarhode-islandsouth-carolinatennesseevermontvirginiawest-virginiawisconsin

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