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

American Bittern Population Trend in Massachusetts

All statesWetland birds

American Bittern in Massachusetts has declined: down 28% on the route-weighted index since 1972.

-28%Since 1972TrendPercent 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 →
12Routes 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 →
22YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable American Bittern Trends in MassachusettsNotable 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 American Bittern in Massachusetts. See the full index history below.

American Bittern Population Forecast in Massachusetts

If the recent trend holds, American Bittern in Massachusetts is projected to fall about 26% by 2028 — from 0.08 in 2023 to a central estimate of 0.06 (95% range 0.00–0.13). A 5-year backtest shows a typical error of ±36.4%, with 100% of held-out values landing inside the 95% band.

-26%Change by 2028TrendPercent 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 →
0.06Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.1395% 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 →
±36.4%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, American Bittern in Massachusetts is projected to fall about 26% by 2028 — from 0.08 in 2023 to a central estimate of 0.06 (95% range 0.00–0.13). A 5-year backtest shows a typical error of ±36.4%, with 100% of held-out values landing inside the 95% band.19692028
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 →
20240.060.000.14
20250.060.000.14
20260.060.000.13
20270.060.000.13
20280.060.000.13

American Bittern Survey Routes in Massachusetts

Routes recording American Bittern in Massachusetts.
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 →
E Dennis119741974
Ware River119941994
Prattville119721972
Newburyport120081985
Maynard119961996
E Pepperell119891975
N Orange120231972
Chesterfield120081971
Cheshire119691969
Warren 2120172017
Sheffield120002000
Monterey120192019

American Bittern Population Trend in Other States

alaskacaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaslouisianamainemarylandmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-dakotaohiooklahomaoregonpennsylvaniasouth-carolinasouth-dakotatexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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