BirdAnalyst
Species · BCR 19 · BBS 2025 Release · 1966–2024

Forster's Tern In Central Mixed Grass Prairie

All regionsCentral Mixed Grass PrairieWetland birds

Forster's Tern in Central Mixed Grass Prairie has declined: down 46% on the route-weighted index since 1969.

-46%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 →
8Routes 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 →
50YearsYears 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 →

No notable trend signals for Forster's Tern in Central Mixed Grass Prairie. See the full index history below.

Forster's Tern In Central Mixed Grass Prairie Population Forecast

If the recent trend holds, Forster's Tern in Central Mixed Grass Prairie is projected to stay roughly flat through 2024, near 0.12 (95% range 0.00–0.45). A 5-year backtest shows a typical error of ±364%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2024TrendPercent 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 →
0.12Projected 2024 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.4595% 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 →
±364%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, Forster's Tern in Central Mixed Grass Prairie is projected to stay roughly flat through 2024, near 0.12 (95% range 0.00–0.45). A 5-year backtest shows a typical error of ±364%, with 100% of held-out values landing inside the 95% band.19672024
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 →
20200.130.000.45
20210.130.000.45
20220.120.000.45
20230.120.000.45
20240.120.000.45

Routes In Central Mixed Grass Prairie

Routes recording Forster's Tern in Central Mixed Grass Prairie.
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 →
LoganKANSAS102001
AlbertKANSAS12019
MisslerKANSAS11989
Piester LakeNEBRASKA12019
KennedyNEBRASKA12014
GordonNEBRASKA12005
Crescent LkNEBRASKA12016
BrownleeNEBRASKA12008

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