BirdAnalyst
Species · BCR 2 · BBS 2025 Release · 1966–2024

Common Eider In BCR 2

All regionsBCR 2Waterfowl

Common Eider in BCR 2 has surged: up 139% on the route-weighted index since 1993.

+139%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 →
5Routes In RegionSurvey 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 SignalsNotable 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 BCR 2: up 139% on the route-weighted index since 1993.

Common Eider In BCR 2 Population Forecast

If the recent trend holds, Common Eider in BCR 2 is projected to rise about 426% by 2029 — from 1.8 in 2024 to a central estimate of 9.3 (95% range 0.61–18). A 5-year backtest shows a typical error of ±307.3%, with 60% of held-out values landing inside the 95% band.

+426%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 →
9.3Projected 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 →
0.61–1895% 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 →
±307.3%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, Common Eider in BCR 2 is projected to rise about 426% by 2029 — from 1.8 in 2024 to a central estimate of 9.3 (95% range 0.61–18). A 5-year backtest shows a typical error of ±307.3%, with 60% of held-out values landing inside the 95% band.19832029
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 →
20258.70.0017
20268.80.1018
20279.00.2718
20289.20.4418
20299.30.6118

Routes In BCR 2

Routes recording Common Eider in BCR 2.
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 →
Kodiak 2ALASKA222009
Cape NomeALASKA162024
KotzebueALASKA152010
CouncilALASKA22023
KodiakALASKA11983

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