BirdAnalyst
Species · BCR 22 · BBS 2025 Release · 1966–2024

Black Tern In Eastern Tallgrass Prairie

All regionsEastern Tallgrass PrairieWetland birds

Black Tern in Eastern Tallgrass Prairie has declined: down 37% on the route-weighted index since 1969.

-37%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 →
22Routes 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 →
26YearsYears 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 Black Tern in Eastern Tallgrass Prairie. See the full index history below.

Black Tern In Eastern Tallgrass Prairie Population Forecast

If the recent trend holds, Black Tern in Eastern Tallgrass Prairie is projected to stay roughly flat through 2029, near 0.04 (95% range 0.00–0.15). A 5-year backtest shows a typical error of ±115.7%, with 80% 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 →
0.04Projected 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 →
0.00–0.1595% 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 →
±115.7%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 Eastern Tallgrass Prairie is projected to stay roughly flat through 2029, near 0.04 (95% range 0.00–0.15). A 5-year backtest shows a typical error of ±115.7%, with 80% 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 →
20250.040.000.15
20260.040.000.15
20270.040.000.15
20280.040.000.15
20290.040.000.15

Routes In Eastern Tallgrass Prairie

Routes recording Black Tern in Eastern Tallgrass 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 →
ExlineIOWA82007
College SpgsIOWA61969
StetMISSOURI51995
GretnaNEBRASKA52015
GeneseoILLINOIS41973
DesmoinesIOWA41968
NeolaIOWA41978
Sioux CityIOWA32024
Rock ValleyIOWA31972
OlsburgKANSAS22007
BarringtonILLINOIS11967
WayneILLINOIS11987
New LenoxILLINOIS11974
ChandlervillILLINOIS11974
MelroseIOWA11989
PiersonIOWA12007
GazaIOWA11969
LafayetteIOWA12003
Ash CreekMINNESOTA11989
LakevilleMINNESOTA11978
KentonOHIO11981
RaymondWISCONSIN12003

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