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

Blue-gray Gnatcatcher Population Trend in Maryland

All statesForest birds

Blue-gray Gnatcatcher in Maryland has surged: up 660% on the route-weighted index since 1968.

+660%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 →
76Routes 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 Blue-gray Gnatcatcher 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-gray Gnatcatcher has surged in Maryland: up 660% on the route-weighted index since 1968.

Blue-gray Gnatcatcher Population Forecast in Maryland

If the recent trend holds, Blue-gray Gnatcatcher in Maryland is projected to fall about 13% by 2029 — from 10 in 2024 to a central estimate of 8.8 (95% range 6.3–11). A 5-year backtest shows a typical error of ±26.3%, with 20% of held-out values landing inside the 95% band.

-13%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 →
8.8Projected 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 →
6.3–1195% 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 →
±26.3%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-gray Gnatcatcher in Maryland is projected to fall about 13% by 2029 — from 10 in 2024 to a central estimate of 8.8 (95% range 6.3–11). A 5-year backtest shows a typical error of ±26.3%, 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 →
20258.25.711
20268.35.911
20278.56.011
20288.66.211
20298.86.311

Blue-gray Gnatcatcher Survey Routes in Maryland

Routes recording Blue-gray Gnatcatcher 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 →
Cokesbury4420241966
Furnace Town4020242015
Pomonkey3920241966
Island Creek2820241991
Forest Grove2720232011
La Plata2620091966
Oldtown2120241970
Olney1920241966
Earlton1720242014
Pomfret1620241966
Berlin1620241980
Ijamsville1620241986
Williamsport1520241973
Nottingham1420242005
Emmitsburg1320241967
Newark1320241966
Madonna1320222009
Tall Timbers1220141966
Wheaton1220241990
Pr Frederick1220241991
Davidsnville1120241982
Smithsburg1020141966
Pt Republic1019891966
Honga920241966
Green Ridge920241995

Blue-gray Gnatcatcher Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemassachusettsmichiganminnesotamississippimissourinebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawest-virginiawisconsinwyoming

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