BirdAnalyst
Species · Tennessee · BBS 2025 Release · 1966–2024

Double-crested Cormorant Population Trend in Tennessee

All statesWetland birds

Double-crested Cormorant in Tennessee has surged: up 431% on the route-weighted index since 1997.

+431%Since 1997TrendPercent 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 →
19Routes In StateSurvey 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 Double-crested Cormorant Trends in TennesseeNotable 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 Tennessee: up 431% on the route-weighted index since 1997.

Double-crested Cormorant Population Forecast in Tennessee

If the recent trend holds, Double-crested Cormorant in Tennessee is projected to fall about 11% by 2029 — from 0.82 in 2024 to a central estimate of 0.72 (95% range 0.14–1.3). A 5-year backtest shows a typical error of ±89.8%, with 40% of held-out values landing inside the 95% band.

-11%Change 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 →
0.72Projected 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 →
0.14–1.395% 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 →
±89.8%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 Tennessee is projected to fall about 11% by 2029 — from 0.82 in 2024 to a central estimate of 0.72 (95% range 0.14–1.3). A 5-year backtest shows a typical error of ±89.8%, with 40% of held-out values landing inside the 95% band.19912029
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 →
20250.640.051.2
20260.660.081.2
20270.680.101.3
20280.700.121.3
20290.720.141.3

Double-crested Cormorant Survey Routes in Tennessee

Routes recording Double-crested Cormorant in Tennessee.
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 →
Pawpaw 21020192013
Big Sandy820242013
Peytonsville720242024
Tiptonville320211991
Brownsville320152015
Signal Mtn220241997
Tullahoma220152015
Pawpaw120111995
Silerton120142014
Humboldt120222008
Pond Creek120012001
Lewis Forest120242024
Belotes Bend120161999
Jasper120182018
Lovell119981998
Corryton Rd120192019
Jefferson Cty120062006
Mt Olive120172010
Allens Brdge120222022

Double-crested Cormorant Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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