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

Red-throated Loon In BCR 4

All regionsBCR 4Wetland birds

Red-throated Loon in BCR 4 has surged: up 115% on the route-weighted index since 1987.

+115%Since 1987TrendPercent 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 →
23Routes 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 →
37YearsYears 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 →

Red-throated Loon has surged in BCR 4: up 115% on the route-weighted index since 1987.

Red-throated Loon In BCR 4 Population Forecast

If the recent trend holds, Red-throated Loon in BCR 4 is projected to fall about 28% by 2030 — from 0.19 in 2025 to a central estimate of 0.14 (95% range 0.03–0.24). A 5-year backtest shows a typical error of ±95.2%, with 80% of held-out values landing inside the 95% band.

-28%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 →
0.14Projected 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 →
0.03–0.2495% 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 →
±95.2%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, Red-throated Loon in BCR 4 is projected to fall about 28% by 2030 — from 0.19 in 2025 to a central estimate of 0.14 (95% range 0.03–0.24). A 5-year backtest shows a typical error of ±95.2%, with 80% 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 →
20260.130.030.24
20270.130.030.24
20280.130.030.24
20290.140.030.24
20300.140.030.24

Routes In BCR 4

Routes recording Red-throated 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 →
Birch LakeALASKA32025
Hather CreekALASKA32015
MonahanALASKA21992
Donelly DomeALASKA22024
Tangle LakesALASKA21987
Kanuti CanynALASKA22024
Anvik RiverALASKA22024
Mccarthy Rd2ALASKA21995
CircleALASKA12025
MaclarenALASKA12025
CantwellALASKA12019
KalifonskyALASKA12014
SourdoughALASKA11996
Lake LouiseALASKA12025
Nicholai SlALASKA12025
PetersvilleALASKA11994
KachemakALASKA12019
Unalakleet RiverALASKA12024
CottonwoodALASKA11988
Mud RiverALASKA12022
Kanuti LakeALASKA12022
Paxson LakeALASKA11993
Nabesna RoadALASKA12014

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