Pelagic Cormorant Life History

Habitat

Habitat Shorelines

Pelagic Cormorants stay close to coastal shorelines and islands, rarely venturing far out to sea. They nest on cliffs and headlands of rocky coasts, where they use narrower ledges and steeper sites than larger cormorants. They also sometimes nest on structures such as disused bridges, piers, ships, towers, or navigation aids. During the day and overnight, they roost in similar rocky habitats on the outer coast as well as in inlets, estuaries, harbors, and lagoons, perching on rocks, pilings, logs, or sometimes sandy beaches. There are very few records of this species inland.

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Food

Food Fish

Pelagic Cormorants eat mostly fish, which they capture at depths as great as 138 feet, seizing prey with the hooked bill. They may remain underwater for over 2 minutes in pursuit of fish, hunting both those that hide in rocky reefs and those that school beneath the surface. They use their large feet to swim and steer underwater. They pry fish and other creatures from rocks, and when hunting schooling fish, they often attack prey from below. They also eat crustaceans, marine worms, and other invertebrates, swallowing smaller prey while still underwater but bringing larger items to the surface to soften before swallowing. Contrary to its English name, this cormorant hunts mostly in nearshore (littoral) waters, in sheltered areas as well as in surf, riptides, and heavy seas. Pelagic Cormorants join flocks of other seabirds where prey is abundant, sometimes hunting in the middle of the aggregations, but they are generally less sociable when foraging than other Pacific cormorant species. Prey items include Pacific herring, Pacific sandlance, crescent gunnel, penpoint gunnel, blackeye goby, northern sculpin, Pacific staghorn sculpin, snake prickleback, three-spined stickleback, flathead clingfish, capelin, walleye pollock, cusk eel, Irish lord, and various other species of smelts, codfishes, sculpins, rockfish, greenlings, gunnels, pricklebacks, scorpionfishes, blennies, gobies, flounders, soles, toadfishes, brotulas, jacks, and clingfish. Other marine creatures in the diet are small crustaceans (amphipods, isopods including woodlice, and crabs), small shrimp, cephalopods, brittle stars, and marine worms (polychaetes).

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Nesting

Nest Placement

Nest Cliff

Males select and defend nest sites, usually on narrow ledges on inaccessible rocky cliffs, facing the sea, sometimes on structures such as shipwrecks, bridges, or navigation towers.

Nest Description

A compact shallow bowl of mostly grass and seaweed, with mosses, sticks, feathers and general marine debris (including rope, plastic, and other human-made objects). The nest is lined with dry vegetation and cemented to the nest ledge with excrement (guano). Nests average 17.3 inches across and 10.2 inches tall, but much larger nests are recorded, especially where an old nest has become the base for a new one.

Nesting Facts
Clutch Size:1-8 eggs
Egg Description:

Greenish white to bluish.

Condition at Hatching:

Naked and helpless.

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Behavior

Behavior Surface Dive

Males are the first to return to nesting cliffs, where they perform wing-waving displays, showing off their white flank patches to returning females. When a female lands beside him, a male then exposes his vivid red mouth lining and bobs his head vigorously. If both agree to pair, the female stays at the nest ledge while the male gathers nesting material. Males continue the wing-waving display during nest building, which is a shared task. When coming and going from the nest, both members of the pair use calls and displays to maintain the pair bond: females bow, both sexes open the bill to display the gape, and both kink the neck when building the nest, sometimes also entwining their necks together. When ready to depart the nest ledge, a member of the pair arches the neck, points the bill downward, and hops like a rabbit a few times, then opens the bill before departing. Such a display usually occurs when one mate relieves the other of incubation duties. Like many seabirds, Pelagic Cormorants perform “reverse” copulation, in which the female mounts the male, probably another method to maintain pair bonds. In some locations, nests are built very close to neighbors, but in many colonies, Pelagics build their nests in isolated sites, out of sight of others of the species. Both parents feed the chicks until fledging, traveling up to 25 miles per day to forage. They add nesting material throughout the nesting season, and older chicks sometimes assist parents in arranging nest material. Males defend the nest site, threatening other males that come too close by waving the wings and head, thrusting the head, and making growling calls. If a rival male attempts to usurp the nest ledge, the owner fights to retain it, jabbing and grasping the opponent by the bill, trying the push him off the ledge. After breeding, the pair separates for 7–8 months. In some areas, Pelagic Cormorants linger after the breeding season at the nest ledge for several months, and return there well before the season recommences, probably to ensure they can reclaim their nest site.

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Conservation

Conservation Low Concern

The North American Breeding Bird Survey indicates a possible steep decline in Pelagic Cormorant populations over the period 1968 to 2015, although this species’ breeding habits makes it difficult to estimate the decline with precision. Partners in Flight estimates a global breeding population of 400,000 birds and rates the species a 13 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. Fishermen sometimes persecute cormorants under the mistaken assumption that the birds eat commercially valuable fish. Fishery operations can also kill many of this species if they use gill nets. Thousands of Pelagic Cormorants perished in the Exxon Valdez oil spill in Alaska in 1989. In the 20th century, high mortality also resulted from organochlorine and PCB pollutants. At colonies, disturbance causes nest losses to predators and nest abandonment.

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Credits

Hobson, Keith A. (2013). Pelagic Cormorant (Phalacrocorax pelagicus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Kushlan, J. A., M. J. Steinkamp, K. C. Parsons, J. Capp, M. A. Cruz, M. Coulter, I. Davidson, L. Dickson, N. Edelson, R. Elliott, R. M. Erwin, S. Hatch, S. Kress, R. Milko, S. Miller, K. Mills, R. Paul, R. Phillips, J. E. Saliva, W. Sydeman, J. Trapp, J. Wheeler and K. Wohl (2002). Waterbird conservation for the Americas: The North American waterbird conservation plan, version 1. Washington, DC, USA.

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sauer, J.R., Niven, D.K., Hines, J.E., Ziolkowski, D.J. Pardieck, K.L., Fallon, J.E., and Link, W.A. (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA. Available from: https://www.mbr-pwrc.usgs.gov/bbs/bbs.html .

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, USA.

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