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

Arctic Tern In Northern Pacific Rainforest

All regionsNorthern Pacific RainforestWetland birds

Arctic Tern in Northern Pacific Rainforest has fallen sharply: down 63% on the route-weighted index since 1983.

-63%Since 1983TrendPercent 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 →
12Routes 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 →
38YearsYears 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 Tern has fallen sharply in Northern Pacific Rainforest: down 63% on the route-weighted index since 1983.

Arctic Tern In Northern Pacific Rainforest Population Forecast

If the recent trend holds, Arctic Tern in Northern Pacific Rainforest is projected to rise about 245% by 2029 — from 0.08 in 2024 to a central estimate of 0.28 (95% range 0.00–0.73). A 5-year backtest shows a typical error of ±136.8%, with 80% of held-out values landing inside the 95% band.

+245%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 →
0.28Projected 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 →
0.00–0.7395% 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 →
±136.8%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 Tern in Northern Pacific Rainforest is projected to rise about 245% by 2029 — from 0.08 in 2024 to a central estimate of 0.28 (95% range 0.00–0.73). A 5-year backtest shows a typical error of ±136.8%, with 80% 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 →
20250.270.000.72
20260.270.000.72
20270.270.000.72
20280.270.000.73
20290.280.000.73

Routes In Northern Pacific Rainforest

Routes recording Arctic Tern 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 →
Moose PassALASKA51992
SkagwayALASKA42024
SewardALASKA31984
CordovaALASKA32012
Mitkof IsleALASKA31989
Copper RiverALASKA32011
Juneau AltALASKA21984
YakutatALASKA22016
Stikine RiverALASKA22022
JuneauALASKA12024
HainesALASKA12024
Sheep MtnALASKA12002

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