BirdAnalyst
Species · BCR 4 · BBS 2026 Release · 1966–2025

Lesser Scaup In BCR 4

All regionsBCR 4Waterfowl

Lesser Scaup in BCR 4 has declined: down 46% on the route-weighted index since 1986.

-46%Since 1986TrendPercent 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 →
28Routes 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 →
41YearsYears 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 →

No notable trend signals for Lesser Scaup in BCR 4. See the full index history below.

Lesser Scaup In BCR 4 Population Forecast

If the recent trend holds, Lesser Scaup in BCR 4 is projected to fall about 100% by 2030 — from 0.14 in 2025 to a central estimate of 0.00 (95% range 0.00–1.3). A 5-year backtest shows a typical error of ±73.5%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–1.395% 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 →
±73.5%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, Lesser Scaup in BCR 4 is projected to fall about 100% by 2030 — from 0.14 in 2025 to a central estimate of 0.00 (95% range 0.00–1.3). A 5-year backtest shows a typical error of ±73.5%, with 100% of held-out values landing inside the 95% band.19822030
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 →
20260.080.001.4
20270.050.001.3
20280.020.001.3
20290.000.001.3
20300.000.001.3

Routes In BCR 4

Routes recording Lesser Scaup in BCR 4.
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 →
Koyukuk Riv.ALASKA161995
MaclarenALASKA82024
Birch LakeALASKA72005
Mud RiverALASKA72021
Paxson LakeALASKA71997
Kanuti LakeALASKA62024
MonahanALASKA52015
Chena Hot Spring 2ALASKA52025
ChistochinaALASKA42008
Mccarthy Rd2ALASKA42023
Lake LouiseALASKA32011
Nabesna RoadALASKA32015
CantwellALASKA22010
ToklatALASKA21999
Nicholai SlALASKA22022
ColdfootALASKA22003
Unalakleet RiverALASKA22013
Kanuti CanynALASKA22007
Galena (Short)ALASKA22000
KuskulanaALASKA22019
CircleALASKA12024
SlanaALASKA12024
NorthwayALASKA12023
Kenny LakeALASKA12019
SourdoughALASKA12022

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