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

Black Tern Population Trend in Minnesota

All statesWetland birds

Black Tern in Minnesota has collapsed: down 84% on the route-weighted index since 1969.

-84%Since 1969TrendPercent 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 →
54Routes 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 →
57YearsYears 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 MinnesotaNotable 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 Minnesota: down 84% on the route-weighted index since 1969.

Black Tern Population Forecast in Minnesota

If the recent trend holds, Black Tern in Minnesota is projected to fall about 62% by 2029 — from 0.34 in 2024 to a central estimate of 0.13 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±96%, with 100% of held-out values landing inside the 95% band.

-62%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 →
0.13Projected 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 →
0.00–1.495% 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 →
±96%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 Minnesota is projected to fall about 62% by 2029 — from 0.34 in 2024 to a central estimate of 0.13 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±96%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20250.250.001.5
20260.220.001.5
20270.190.001.5
20280.160.001.4
20290.130.001.4

Black Tern Survey Routes in Minnesota

Routes recording Black Tern in Minnesota.
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 →
Bagley2020061995
Greenbush1620221996
Chokio North1320111993
Sherburne Nr1120241990
Maynard1019711967
Backus820021968
Sherry Lake819821969
Knapp720241967
Gluek720041967
Grygla720031980
Worthington720062005
Big Stone720111995
Chandler619711969
Tenney620141978
Appleton520221986
Chokio520221969
Redwood Fall419841980
Pine River420001967
Bena419771967
Ashby420161997
Oklee319691969
Money Creek220111974
St Stephen220051967
Glyndon220211978
Lake Bronson219991978

Black Tern Population Trend in Other States

californiacoloradoidahoillinoisindianaiowakansasmainemichiganmissourimontananebraskanevadanew-yorknorth-dakotaohiooregonsouth-dakotatexasutahwashingtonwisconsinwyoming

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