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

Common Eider Population Trend in Maine

All statesWaterfowl

Common Eider in Maine has surged: up 29× on the route-weighted index since 1993.

29×Since 1993TrendPercent 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 →
26YearsYears 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 Eider Trends in MaineNotable 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 →

Common Eider has surged in Maine: up 29× on the route-weighted index since 1993.

Common Eider Population Forecast in Maine

If the recent trend holds, Common Eider in Maine is projected to fall about 14% by 2030 — from 4.1 in 2025 to a central estimate of 3.5 (95% range 0.88–6.2). A 5-year backtest shows a typical error of ±61.2%, with 20% of held-out values landing inside the 95% band.

-14%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 →
3.5Projected 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 →
0.88–6.295% 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 →
±61.2%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 Eider in Maine is projected to fall about 14% by 2030 — from 4.1 in 2025 to a central estimate of 3.5 (95% range 0.88–6.2). A 5-year backtest shows a typical error of ±61.2%, with 20% of held-out values landing inside the 95% band.19782030
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 →
20263.10.485.8
20273.30.585.9
20283.30.686.0
20293.40.786.1
20303.50.886.2

Common Eider Survey Routes in Maine

Routes recording Common Eider in Maine.
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 →
Kittery Pt7420251978
Newcastle519971997
Forest Sta119841984

Common Eider Population Trend in Other States

alaska

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