BirdAnalyst
Species · BCR 4 · BBS 2025 Release · 1966–2024

Pacific Loon In BCR 4

All regionsBCR 4Wetland birds

Pacific Loon in BCR 4 has fallen sharply: down 65% on the route-weighted index since 1985.

-65%Since 1985TrendPercent 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 →
32Routes 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 →
40YearsYears 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 declinecomputed 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 →

Pacific Loon has fallen sharply in BCR 4: down 65% on the route-weighted index since 1985.

Forecast

If the recent trend holds, Pacific Loon in BCR 4 is projected to fall about 63% by 2029 — from 0.22 in 2024 to a central estimate of 0.08 (95% range 0.00–0.49). A 5-year backtest shows a typical error of ±43.2%, with 100% of held-out values landing inside the 95% band.

-63%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 →
0.08Projected 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 →
0.00–0.4995% 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 →
±43.2%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, Pacific Loon in BCR 4 is projected to fall about 63% by 2029 — from 0.22 in 2024 to a central estimate of 0.08 (95% range 0.00–0.49). A 5-year backtest shows a typical error of ±43.2%, with 100% 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 →
20250.110.000.52
20260.100.000.51
20270.100.000.50
20280.090.000.50
20290.080.000.49

Routes In BCR 4

Routes recording Pacific Loon 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 →
Swan Lake RdALASKA32023
Anvik RiverALASKA32021
Hatcher PassALASKA22017
CohoeALASKA22018
Nicholai SlALASKA22024
Seven LakesALASKA22010
Burma RoadALASKA22011
Donelly DomeALASKA22012
Unalakleet RiverALASKA22017
Hather CreekALASKA22016
Porcupine R.ALASKA22002
Paxson LakeALASKA21996
Nabesna RoadALASKA22024
KuskulanaALASKA22023
Mccarthy Rd2ALASKA22024
CircleALASKA12024
Birch LakeALASKA12011
SlanaALASKA12004
NorthwayALASKA12015
MaclarenALASKA11991
MonahanALASKA11987
KalifonskyALASKA12014
MatanuskaALASKA11983
WillowALASKA12024
SourdoughALASKA12009

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