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

Double-crested Cormorant In Eastern Tallgrass Prairie

All regionsEastern Tallgrass PrairieWetland birds

Double-crested Cormorant in Eastern Tallgrass Prairie has surged: up 859% on the route-weighted index since 1982.

+859%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 →
79Routes 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 →
40YearsYears 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 increasecomputed 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 →

Double-crested Cormorant has surged in Eastern Tallgrass Prairie: up 859% on the route-weighted index since 1982.

Forecast

If the recent trend holds, Double-crested Cormorant in Eastern Tallgrass Prairie is projected to stay roughly flat through 2029, near 0.27 (95% range 0.04–0.51). A 5-year backtest shows a typical error of ±445.7%, with 40% 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 →
0.27Projected 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 →
0.04–0.5195% 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 →
±445.7%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, Double-crested Cormorant in Eastern Tallgrass Prairie is projected to stay roughly flat through 2029, near 0.27 (95% range 0.04–0.51). A 5-year backtest shows a typical error of ±445.7%, with 40% of held-out values landing inside the 95% band.19742029
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 →
20250.260.020.50
20260.260.020.50
20270.270.030.50
20280.270.030.51
20290.270.040.51

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
WalesIOWA131991
BarringtonILLINOIS102012
WainwrightOKLAHOMA91997
YorkvilleILLINOIS82019
DudleyvilleILLINOIS72021
JohnsonNEBRASKA71988
BarclayKANSAS61998
AtkinsonILLINOIS52019
St MorganILLINOIS52022
SenecaILLINOIS42019
Trading PostKANSAS42016
New PointMISSOURI42019
ItascaILLINOIS32022
WayneILLINOIS32024
JanesvilleILLINOIS32022
FloraILLINOIS31995
Lake SummersetILLINOIS32013
MaquoketaIOWA31994
Ash CreekMINNESOTA32013
FrazierMISSOURI32017
BotkinsOHIO31998
BartonvilleILLINOIS22022
MonticelloILLINOIS22021
BelleviewILLINOIS22007

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