Species

Double-crested cormorant

Nannopterum auritum

A black diving bird with a hooked bill and turquoise eyes, often seen standing with wings spread on posts and docks.

Photo Frank Schulenburg (opens in a new tab) / Wikimedia Commons, CC BY-SA 4.0 (opens in a new tab)

Misconceptions

At a glance

Size: About 70 to 90 cm long; wingspan about 1.1 to 1.2 m
Weight: About 1.2 to 2.5 kg
Habitat: Lakes, rivers, reservoirs, coasts and harbours
Diet: Fish
In Georgia: Common all year; more numerous in winter
Voice: Grunts at colonies; silent elsewhere
Rabies vector: No

Identification

Key marks: Black with an orange-yellow throat patch; hooked bill; turquoise-green eyes; small tufts of feathers on the head in breeding season
Told apart from: Anhinga, which has a straight, pointed bill and long tail
Told apart from: Neotropic cormorant, which is smaller with a longer tail and a white edge to the throat patch
Where to look: Perched on posts, buoys and dead trees near water

Behaviour

Cormorants dive from the surface and chase fish underwater with their feet. Their feathers are partly wettable, reducing buoyancy, and they spread their wings to dry after fishing.

Why they matter

Double-crested cormorants were nearly wiped out in the mid-1900s by the pesticide DDT, which thinned their eggshells. Their recovery since DDT was banned is one of the clearest signs of how much cleaner many waters have become.

Reproduction and lifecycle

Nest — A platform of sticks in trees or on the ground, in colonies
Eggs — Usually three or four
Incubation — About 25 to 28 days
Chicks — Hatched naked; fed by both parents
Flight — At about six to seven weeks
Lifespan — Wild birds over twenty years are recorded

Living around people

Fishing line is a common cause of injury; a hooked or tangled cormorant needs a rehabilitator.
A cormorant with wings spread is drying off, not hurt.

Misconceptions

Cormorants empty lakes of fish. Most of what they eat is small fish of little interest to anglers. Effects on fisheries are real in a few places, but far smaller than their reputation.
Wet feathers mean a sick bird. Cormorants' feathers are designed to get wet.

Related species

Seasonal activity

When this species is breeding, and when there are nests on the ground. Mowing during the shaded months is how most nests are found.

Breeding and active nests by month for this species
	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Breeding	Jan: no	Feb: no	Mar: no	Apr: no	May: no	Jun: no	Jul: no	Aug: no	Sep: no	Oct: no	Nov: no	Dec: no
Active nests	Jan: no	Feb: no	Mar: no	Apr: no	May: no	Jun: no	Jul: no	Aug: no	Sep: no	Oct: no	Nov: no	Dec: no
Notes	Large wintering flocks	Wintering	Migrants leaving	Nesting in colonies	Nesting	Chicks	Young flying	Families	Migrants arriving	Flocks building	Wintering flocks	Wintering

Where it lives

Recorded in 76 states and provinces. Each one links to the other animals there, and to the rehabilitators licensed for them.

Canada

Mexico

If you found one

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