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

Double-crested Cormorant Population Trend in Connecticut

All statesWetland birds

Double-crested Cormorant in Connecticut has fallen sharply: down 55% on the route-weighted index since 1981.

-55%Since 1981
12Routes In State
34Years

Notable Double-crested Cormorant Trends in Connecticut

long arc declinecomputed index

Double-crested Cormorant has fallen sharply in Connecticut: down 55% on the route-weighted index since 1981.

Double-crested Cormorant Population Forecast in Connecticut

If the recent trend holds, Double-crested Cormorant in Connecticut is projected to rise about 16% by 2029 — from 0.11 in 2024 to a central estimate of 0.13 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±41.7%, with 100% of held-out values landing inside the 95% band.

+16%Change by 2029
0.13Projected 2029 index
0.00–1.495% range
±41.7%Backtest error
19792029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected index95% low95% high
20250.190.001.4
20260.180.001.4
20270.160.001.4
20280.140.001.4
20290.130.001.4

Double-crested Cormorant Survey Routes in Connecticut

Routes recording Double-crested Cormorant in Connecticut.
New Hartford1119861986
Danbury720131988
New Hartford420032003
Mid Haddam420221988
Uncasville320232022
Mystic220221979
Woodstock 2220182018
Southington220062006
Westbrook120241979
Willimantic120171990
Sherman120062001
Greenwich120181991

Double-crested Cormorant Population Trend in Other States

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