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

Common Eider Population Trend in Maine

All statesWaterfowl

Common Eider in Maine has surged: up 26× on the route-weighted index since 1993.

26×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 →
25YearsYears 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 26× 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 rise about 28% by 2029 — from 2.7 in 2024 to a central estimate of 3.4 (95% range 0.42–6.4). A 5-year backtest shows a typical error of ±75.5%, with 0% of held-out values landing inside the 95% band.

+28%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 →
3.4Projected 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 →
0.42–6.495% 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 →
±75.5%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 rise about 28% by 2029 — from 2.7 in 2024 to a central estimate of 3.4 (95% range 0.42–6.4). A 5-year backtest shows a typical error of ±75.5%, with 0% of held-out values landing inside the 95% band.19782029
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 →
20253.00.026.0
20263.10.126.1
20273.20.226.2
20283.30.326.3
20293.40.426.4

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 Pt5120241978
Newcastle519971997
Forest Sta119841984

Common Eider Population Trend in Other States

alaska

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