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Species · BCR 5 · BBS 2025 Release · 1966–2024

Harlequin Duck In Northern Pacific Rainforest

All regionsNorthern Pacific RainforestWaterfowl

Harlequin Duck in Northern Pacific Rainforest has risen sharply: up 63% on the route-weighted index since 1984.

+63%Since 1984TrendPercent 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 →
18Routes 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 →
35YearsYears 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 →

Harlequin Duck has risen sharply in Northern Pacific Rainforest: up 63% on the route-weighted index since 1984.

Harlequin Duck In Northern Pacific Rainforest Population Forecast

If the recent trend holds, Harlequin Duck in Northern Pacific Rainforest is projected to fall about 67% by 2029 — from 0.20 in 2024 to a central estimate of 0.07 (95% range 0.00–0.57). A 5-year backtest shows a typical error of ±90.5%, with 100% of held-out values landing inside the 95% band.

-67%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 →
0.07Projected 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 →
0.00–0.5795% 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 →
±90.5%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, Harlequin Duck in Northern Pacific Rainforest is projected to fall about 67% by 2029 — from 0.20 in 2024 to a central estimate of 0.07 (95% range 0.00–0.57). A 5-year backtest shows a typical error of ±90.5%, with 100% of held-out values landing inside the 95% band.19752029
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 →
20250.090.000.58
20260.080.000.58
20270.080.000.57
20280.070.000.57
20290.070.000.57

Routes In Northern Pacific Rainforest

Routes recording Harlequin Duck in Northern Pacific Rainforest.
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 →
ZaremboALASKA472001
Thorne BayALASKA181994
Mitkof IsleALASKA161995
Thorne Bay 2ALASKA82023
SkagwayALASKA82024
Zimovia StrtALASKA72024
Sitka (Short)ALASKA51992
JuneauALASKA42023
PetersburgALASKA41987
Juneau AltALASKA31985
HainesALASKA22022
SitkaALASKA22022
HyderALASKA22007
Stikine RiverALASKA22007
Warm BeachWASHINGTON22006
Hurricane RgWASHINGTON22023
YakutatALASKA12002
Fish RockCALIFORNIA11982

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