BirdAnalyst
Species · Maryland · BBS 2026 Release · 1966–2025

Blue Grosbeak Population Trend in Maryland

All statesForest birds

Blue Grosbeak in Maryland has surged: up 221% on the route-weighted index since 1968.

+221%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 →
69Routes 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 →
59YearsYears 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 Grosbeak 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 Grosbeak has surged in Maryland: up 221% on the route-weighted index since 1968.

Blue Grosbeak Population Forecast in Maryland

If the recent trend holds, Blue Grosbeak in Maryland is projected to stay roughly flat through 2030, near 9.0 (95% range 6.6–11). A 5-year backtest shows a typical error of ±7.1%, with 100% of held-out values landing inside the 95% band.

+1%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 →
9.0Projected 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 →
6.6–1195% 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 →
±7.1%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, Blue Grosbeak in Maryland is projected to stay roughly flat through 2030, near 9.0 (95% range 6.6–11). A 5-year backtest shows a typical error of ±7.1%, with 100% 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 →
20268.66.211
20278.76.311
20288.86.411
20298.96.511
20309.06.611

Blue Grosbeak Survey Routes in Maryland

Routes recording Blue Grosbeak 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 →
Cokesbury5520251966
Harmony4320171966
Honga2820251966
Furnace Town2720252015
Mardela2620191967
St. George'S Island2520172015
Tall Timbers2420141966
Walnut2320241999
La Plata2120091966
Vienna2120251966
Newark2120251966
Berlin2120251980
Forest Grove2020232011
Madison1920251967
Easton1820251966
Golden Hill1820251966
Indiantown1820141977
Pt Republic1619891966
Sinepuxent1619781966
Millington1520251966
Pr Frederick1420251991
Hughesville1020251966
Island Creek1020251991
Cheltenham920041966
Melitota920251966

Blue Grosbeak Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradodelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianaminnesotamississippimissourimontananebraskanevadanew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniasouth-carolinasouth-dakotatennesseetexasutahvirginiawest-virginiawyoming

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