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

Least Bittern Population Trend in Arizona

All statesWetland birds

Least Bittern in Arizona has fallen sharply: down 56% on the route-weighted index since 2002.

-56%Since 2002TrendPercent 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 →
18YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Least Bittern Trends in ArizonaNotable 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 Least Bittern in Arizona. See the full index history below.

Least Bittern Population Forecast in Arizona

If the recent trend holds, Least Bittern in Arizona is projected to stay roughly flat through 2028, near 0.04 (95% range 0.00–0.11). A 5-year backtest shows a typical error of ±304.3%, with 20% of held-out values landing inside the 95% band.

n/aChange 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 →
0.04Projected 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 →
0.00–0.1195% 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 →
±304.3%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, Least Bittern in Arizona is projected to stay roughly flat through 2028, near 0.04 (95% range 0.00–0.11). A 5-year backtest shows a typical error of ±304.3%, with 20% of held-out values landing inside the 95% band.20002028
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 →
20240.050.000.12
20250.040.000.12
20260.040.000.12
20270.040.000.11
20280.040.000.11

Least Bittern Survey Routes in Arizona

Routes recording Least Bittern in Arizona.
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 →
Cibola Lake320172002
Laguna120102000
Araby120232000

Least Bittern Population Trend in Other States

alabamaarkansascaliforniaconnecticutdelawarefloridageorgiaillinoisindianaiowakansaslouisianamarylandmichiganminnesotamississippimissourinebraskanevadanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooregonsouth-carolinasouth-dakotatexasvermontvirginiawisconsin

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