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Species · Maryland · BBS 2025 Release · 1966–2024

Common Gallinule Population Trend in Maryland

All statesWetland birds

Common Gallinule in Maryland has declined: down 27% on the route-weighted index since 1975.

-27%Since 1975TrendPercent 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 →
3Routes 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 →
24YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Common Gallinule 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 →

No notable trend signals for Common Gallinule in Maryland. See the full index history below.

Common Gallinule Population Forecast in Maryland

If the recent trend holds, Common Gallinule in Maryland is projected to stay roughly flat through 2027, near 0.02 (95% range 0.00–0.03). A 5-year backtest shows a typical error of ±20.2%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2027TrendPercent 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 →
0.02Projected 2027 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.0395% 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 →
±20.2%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, Common Gallinule in Maryland is projected to stay roughly flat through 2027, near 0.02 (95% range 0.00–0.03). A 5-year backtest shows a typical error of ±20.2%, with 100% of held-out values landing inside the 95% band.19722027
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 →
20230.020.000.04
20240.020.000.04
20250.020.000.03
20260.020.000.03
20270.020.000.03

Common Gallinule Survey Routes in Maryland

Routes recording Common Gallinule 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 →
Honga120121972
Madison119881988
Cokesbury120221986

Common Gallinule Population Trend in Other States

alabamaarizonaarkansascaliforniaconnecticutdelawarefloridageorgiaillinoisindianakansaskentuckylouisianamainemassachusettsmichiganminnesotamississippinevadanew-jerseynew-yorknorth-carolinaohiopennsylvaniasouth-carolinatennesseetexasutahvermontwisconsin

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