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

Arctic Warbler In BCR 4

All regionsBCR 4Generalists

Arctic Warbler in BCR 4 has fallen sharply: down 56% on the route-weighted index since 1984.

-56%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 →
22Routes 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 →
39YearsYears 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 →

Arctic Warbler has fallen sharply in BCR 4: down 56% on the route-weighted index since 1984.

Arctic Warbler In BCR 4 Population Forecast

If the recent trend holds, Arctic Warbler in BCR 4 is projected to fall about 52% by 2029 — from 3.3 in 2024 to a central estimate of 1.6 (95% range 0.00–6.3). A 5-year backtest shows a typical error of ±50.5%, with 100% of held-out values landing inside the 95% band.

-52%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 →
1.6Projected 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 →
0.00–6.395% 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 →
±50.5%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, Arctic Warbler in BCR 4 is projected to fall about 52% by 2029 — from 3.3 in 2024 to a central estimate of 1.6 (95% range 0.00–6.3). A 5-year backtest shows a typical error of ±50.5%, with 100% of held-out values landing inside the 95% band.19822029
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 →
20251.90.006.6
20261.80.006.5
20271.80.006.4
20281.70.006.3
20291.60.006.3

Routes In BCR 4

Routes recording Arctic Warbler 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 →
MaclarenALASKA932024
Paxson LakeALASKA401997
MonahanALASKA122021
ToklatALASKA122024
CantwellALASKA102021
SavageALASKA92024
McgrathALASKA72022
TatalinaALASKA62019
ColdfootALASKA42022
Chena Hot SpALASKA31987
RubyALASKA32024
Mud RiverALASKA22024
Pinoche Tral (Short)ALASKA21984
Lake LouiseALASKA11997
Nicholai SlALASKA12023
PetersvilleALASKA12011
Caribou Mtn.ALASKA12011
Hather CreekALASKA12024
Kanuti CanynALASKA12007
Ft. RichrdsnALASKA11997
Anvik RiverALASKA11999
Galena (Short)ALASKA12023

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