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Species · BCR 2 · BBS 2026 Release · 1966–2025

Arctic Tern In BCR 2

All regionsBCR 2Wetland birds

Arctic Tern in BCR 2 has surged: up 89% on the route-weighted index since 1985.

+89%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 →
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 →
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 →

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 →

Arctic Tern has surged in BCR 2: up 89% on the route-weighted index since 1985.

Arctic Tern In BCR 2 Population Forecast

If the recent trend holds, Arctic Tern in BCR 2 is projected to rise about 170% by 2030 — from 3.8 in 2025 to a central estimate of 10 (95% range 0.00–25). A 5-year backtest shows a typical error of ±563.7%, with 100% of held-out values landing inside the 95% band.

+170%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 →
10Projected 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 →
0.00–2595% 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 →
±563.7%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 BCR 2 is projected to rise about 170% by 2030 — from 3.8 in 2025 to a central estimate of 10 (95% range 0.00–25). A 5-year backtest shows a typical error of ±563.7%, with 100% of held-out values landing inside the 95% band.19832030
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 →
2026100.0025
2027100.0025
2028100.0025
2029100.0025
2030100.0025

Routes In BCR 2

Routes recording Arctic Tern in BCR 2.
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 →
Goodnews BayALASKA632005
Kanektok RivALASKA482005
Cape NomeALASKA342024
Togiak RiverALASKA262005
NomeALASKA112023
Cold BayALASKA102025
KotzebueALASKA72025
Cold Bay (Short)ALASKA51991
KodiakALASKA31983
Kodiak 2ALASKA32019
St. Mary'SALASKA31994
Kugarak (Short)ALASKA31987
Katmai N.P.ALASKA22025
ChiniakALASKA22025
King SalmonALASKA22025
Gweek RiverALASKA22002
TupuknukALASKA21995
Selawik (Short)ALASKA21987
DillinghamALASKA12019
CouncilALASKA12010
Salmon LakeALASKA12023
TellerALASKA12009
Kotzebue (Short)ALASKA11994

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