BirdAnalyst
Species · BCR 22 · BBS 2026 Release · 1966–2025

Double-crested Cormorant In Eastern Tallgrass Prairie

All regionsEastern Tallgrass PrairieWetland birds

Double-crested Cormorant in Eastern Tallgrass Prairie has surged: up 19× on the route-weighted index since 1982.

19×Since 1982TrendPercent 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 →
84Routes 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 →
41YearsYears 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 Double-crested Cormorant in Eastern Tallgrass Prairie. See the full index history below.

Double-crested Cormorant In Eastern Tallgrass Prairie Population Forecast

If the recent trend holds, Double-crested Cormorant in Eastern Tallgrass Prairie is projected to fall about 21% by 2030 — from 0.36 in 2025 to a central estimate of 0.29 (95% range 0.05–0.53). A 5-year backtest shows a typical error of ±412.1%, with 40% of held-out values landing inside the 95% band.

-21%Change by 2030TrendPercent 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 →
0.29Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.05–0.5395% 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 →
±412.1%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, Double-crested Cormorant in Eastern Tallgrass Prairie is projected to fall about 21% by 2030 — from 0.36 in 2025 to a central estimate of 0.29 (95% range 0.05–0.53). A 5-year backtest shows a typical error of ±412.1%, with 40% of held-out values landing inside the 95% band.19742030
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 →
20260.270.030.51
20270.280.040.51
20280.280.040.52
20290.280.050.52
20300.290.050.53

Routes In Eastern Tallgrass Prairie

Routes recording Double-crested Cormorant 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 →
NilwoodILLINOIS231995
BeaucoupILLINOIS222025
SenecaILLINOIS182025
WalesIOWA131991
BarringtonILLINOIS102012
WainwrightOKLAHOMA91997
YorkvilleILLINOIS82019
DudleyvilleILLINOIS72021
LacledeMISSOURI72025
JohnsonNEBRASKA71988
BarclayKANSAS61998
AtkinsonILLINOIS52019
St MorganILLINOIS52022
Trading PostKANSAS52025
WayneILLINOIS42025
New PointMISSOURI42019
JanesvilleILLINOIS32022
FloraILLINOIS31995
Lake SummersetILLINOIS32013
MelroseIOWA32025
MaquoketaIOWA31994
Ash CreekMINNESOTA32013
FrazierMISSOURI32017
BotkinsOHIO31998
BartonvilleILLINOIS22022

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.