BirdAnalyst
Species · BCR 12 · BBS 2025 Release · 1966–2024

Black Tern In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionWetland birds

Black Tern in Boreal Hardwood Transition has collapsed: down 85% on the route-weighted index since 1969.

-85%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 →
33Routes 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 →
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 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 →

Black Tern has collapsed in Boreal Hardwood Transition: down 85% on the route-weighted index since 1969.

Black Tern In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Black Tern in Boreal Hardwood Transition is projected to stay roughly flat through 2029, near 0.15 (95% range 0.00–0.69). A 5-year backtest shows a typical error of ±1151%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.15Projected 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 →
0.00–0.6995% 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 →
±1151%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 Boreal Hardwood Transition is projected to stay roughly flat through 2029, near 0.15 (95% range 0.00–0.69). A 5-year backtest shows a typical error of ±1151%, 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 →
20250.170.000.70
20260.160.000.69
20270.160.000.69
20280.160.000.69
20290.150.000.69

Routes In Boreal Hardwood Transition

Routes recording Black Tern in Boreal Hardwood Transition.
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 →
BagleyMINNESOTA202006
GreenbushMINNESOTA162022
BackusMINNESOTA82002
Sherry LakeMINNESOTA81982
BerglandMICHIGAN61982
Land O LakesWISCONSIN61981
Pine RiverMINNESOTA42000
BenaMINNESOTA41977
BashawWISCONSIN42004
PickfordMICHIGAN31981
Union TwpWISCONSIN32006
McgregorMINNESOTA22021
BrainerdMINNESOTA22014
Cass LakeMINNESOTA21980
MinongWISCONSIN21980
PhillipsWISCONSIN21969
IrmaWISCONSIN21978
HollisterWISCONSIN21967
TahquamenonMICHIGAN11988
Seney NwrMICHIGAN12006
Wigwam BayMINNESOTA12021
BemidjiMINNESOTA11979
DebsMINNESOTA12024
BlackduckMINNESOTA12011
NebishMINNESOTA12016

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