BirdAnalyst
Species · BCR 10 · BBS 2025 Release · 1966–2024

Black Tern In Northern Rockies

All regionsNorthern RockiesWetland birds

Black Tern in Northern Rockies has collapsed: down 78% on the route-weighted index since 1971.

-78%Since 1971TrendPercent 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 →
15Routes 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 →
49YearsYears 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 Northern Rockies: down 78% on the route-weighted index since 1971.

Black Tern In Northern Rockies Population Forecast

If the recent trend holds, Black Tern in Northern Rockies is projected to stay roughly flat through 2029, near 0.13 (95% range 0.00–0.43). A 5-year backtest shows a typical error of ±826%, 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 →
0.13Projected 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 →
0.00–0.4395% 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 →
±826%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 Northern Rockies is projected to stay roughly flat through 2029, near 0.13 (95% range 0.00–0.43). A 5-year backtest shows a typical error of ±826%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20250.130.000.43
20260.130.000.43
20270.130.000.43
20280.130.000.43
20290.130.000.43

Routes In Northern Rockies

Routes recording Black Tern in Northern Rockies.
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 →
KalispellMONTANA72018
NaplesIDAHO62022
GeboWYOMING61993
St MaryMONTANA32002
Pablo Res.MONTANA22017
GlenMONTANA21978
Twin LakesWASHINGTON22010
CurlewWASHINGTON21992
ArleeMONTANA11984
AugustaMONTANA11985
Mount VernonOREGON12009
RandolphUTAH12024
Neponset ResUTAH12004
ChewelahWASHINGTON12012
Green RiverWYOMING11982

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