Double-crested CormorantNannopterum auritumWhere and when to see them

The Double-crested Cormorant is a dark, long-necked fishing bird whose shape becomes familiar once watched both on and off the water. It sits low when swimming, then may stand upright on a perch with wings extended after a feeding bout. Yellow-orange facial skin gives colour to an otherwise subdued adult. Cornell identifies it as a foot-propelled underwater hunter and notes use of both fresh and salt water. The Columbia and Upper Mississippi records direct attention to feeding pools and resting structures at particular refuge reaches. A line of perched birds can be easier to locate than a submerged feeding flock, so scan exposed timber and markers as carefully as open water.

Size

Not verified

Weight

Not verified

Lifespan

Not verified

Status

Cornell: Low Concern; not an IUCN category.

Cormorants chase fish below the surface using their webbed feet, then rest and digest on exposed perches. Wing-spreading after fishing is a characteristic observation, though it should be described as natural behaviour rather than induced by disturbance. Birds breed colonially and may nest in trees, on rocks or on the ground. Cornell notes that accumulated guano can kill colony trees, after which nesting may shift as supports deteriorate. Feeding and resting locations need not be immediately adjacent, so a commuting line does not necessarily mark a nearby colony. Watch from established viewpoints, avoiding landing on occupied islands or approaching a perch closely enough to send birds back into the water.

• The feet propel underwater pursuit.
• The bill has a hooked tip.
• Most food is fish.
• Birds rest on exposed perches.
• Wing-spreading is characteristic after fishing.
• Young birds are paler than adults.
• Facial skin is yellow-orange.
• Nesting colonies can occupy trees or the ground.
• Accumulated guano can kill colony trees.

No numerical local viewing calendar is verified for the registered Columbia, Mississippi associations. Feeding flocks and resting groups may use different sites, sometimes well separated. The presence of a colony or a favourite perch does not establish a monthly visitor calendar for the adjacent navigation route.

Large enough waters to support fish are central, but colonies or roosts can occupy smaller ponds and lagoons some distance from feeding areas. Exposed rocks, dead trees, docks and other airy structures provide resting places. This combination makes the whole waterside landscape relevant: the feeding pool and the perch are different resources. At Umatilla and Upper Mississippi sites, use authorised shore views to inspect both water and visible resting structures. Do not approach navigation markers or assume that an occupied tree is publicly accessible. A colony’s ecological effects, including guano beneath nests, are part of its habitat use, not a reason for visitors to interfere with the birds or their supports.

Fish account for almost all of the Double-crested Cormorant’s diet, though small amounts of crustaceans, insects and amphibians are recorded by Cornell. The hooked bill tip helps seize prey during underwater pursuit. Captured crustaceans may be manipulated before swallowing, while fish can be difficult to identify after a quick surface handling action. The species takes many kinds of fish rather than depending universally on one prey species. A visible group diving in sequence may be using a rich patch, but an observer cannot reliably assess fish stocks or competition from a brief sighting. Describe the feeding action and any clearly visible prey without extrapolating to the health of the whole river.

Common name

Double-crested Cormorant

Scientific name

Nannopterum auritum

Animal group

Birds

Size

Not verified in the accessible source text.

Weight

Not verified in the accessible source text.

Lifespan

Wild lifespan not verified in the accessible source text.

Status

Cornell: Low Concern; not an IUCN category.

Identification

Adults are dark with long necks, hooked bills and yellow-orange facial skin. On water they sit low, often with the bill tilted slightly upward; perched birds may show an S-shaped neck curve. Young birds are paler than adults and should not be rejected because the breast is not uniformly dark. The namesake crests are not a dependable year-round field mark. In flight, use the long neck, heavy body and laboured wingbeats alongside flock shape. Other cormorants can resemble this species, so facial pattern, size and proportions matter where ranges overlap. A distant black waterbird is not securely identified by wing-spreading alone.