BirdAnalyst
Species · Oregon · BBS 2025 Release · 1966–2024

Black Tern Population Trend in Oregon

All statesWetland birds

Black Tern in Oregon has collapsed: down 95% on the route-weighted index since 1972.

-95%Since 1972TrendPercent 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 →
17Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
51YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Black Tern Trends in OregonNotable 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 →

Black Tern has collapsed in Oregon: down 95% on the route-weighted index since 1972.

Black Tern Population Forecast in Oregon

If the recent trend holds, Black Tern in Oregon is projected to fall about 100% by 2029 — from 0.18 in 2024 to a central estimate of 0.00 (95% range 0.00–0.97). A 5-year backtest shows a typical error of ±120.5%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–0.9795% 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 →
±120.5%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, Black Tern in Oregon is projected to fall about 100% by 2029 — from 0.18 in 2024 to a central estimate of 0.00 (95% range 0.00–0.97). A 5-year backtest shows a typical error of ±120.5%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.030.001.00
20260.010.000.98
20270.000.000.97
20280.000.000.97
20290.000.000.97

Black Tern Survey Routes in Oregon

Routes recording Black Tern in Oregon.
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 →
Warner Vally3520072003
Catlow Rim2020162013
Fish Lake1720241972
Blizzard Gap1220051987
Bly1020011992
Chinchalo720211993
Barnes Val519871974
Adair420012001
Harney Lake420031996
Dell Spring219761976
Modoc Point220021969
Merrill120052005
Lapham Res.120071991
Mount Vernon120091987
Princeton119851972
Lakeview120051999
Malheur Nwr119981986

Black Tern Population Trend in Other States

californiacoloradoidahoillinoisindianaiowakansasmainemichiganminnesotamissourimontananebraskanevadanew-yorknorth-dakotaohiosouth-dakotatexasutahwashingtonwisconsinwyoming

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