Elegant Tern Life History

Habitat

Elegant Terns nest only on two islands in the Gulf of California (Sea of Cortez), Isla Montague and Isla Rasa, Mexico; and on a few isolated beaches in California. These sites are mostly flat, sandy places with scattered shells and little vegetation, but the largest colony (at volcanic Isla Rasa) nests on pebbly ground. Several of the California colonies nest on sandy dredge spoil. Elegant Terns forage mostly in open ocean waters, but they sometimes fly up estuaries if prey is available. Records from freshwater and away from the ocean are very rare. When not nesting or foraging, Elegant Terns roost on beaches, mudflats, rocks, and pilings (or similar artificial structures) on the coast.

Food

Elegant Terns eat mostly small, schooling fish, which they capture by plunge-diving from the air into the sea surface, grasping the prey in the bill. Typically, only a few Elegant Terns feed near one another, but hundreds may gather when prey are abundant and concentrated. Their chief prey is northern anchovy, but they also eat Pacific sardine, Pacific mackerel, jack mackerel, topsmelt, longjaw mudsucker, grunion, and various silversides, gobies, chubs, and cusk eels. On rare occasions, they eat small crustaceans. When courtship-feeding and when feeding young, Elegant Terns bring small fish in their bill back to the mate or chick, sometimes traveling up to 15 miles to catch just a single fish. Gulls and Parasitic Jaegers often harass them in an attempt to steal the fish.

Nesting

Nest Placement

Females probably select the nest site. Nests are set on flat pebbly, shelly, or sandy ground on beaches, dredge spoil sites, dikes, or islands.

Nest Description

Nests consist of shallow scrapes in sand or other substrate, sometimes lined with shells or pebbles. Both adults build up a rim around the scrape, using whatever objects are near the nest (shells, feathers, bones, twigs). Nests average about 6 inches across.

Nesting Facts

Behavior

Elegant Terns nest in dense colonies. Some arrive at the colony already paired, but others associate in “clubs,” small flocks that gather on the periphery of the colony and socialize. Clubs probably consist of younger or unpaired birds looking for mates. Once paired, Elegant Terns begin courtship displays, both in the air and on the ground. On land, females lower the head in a “groveling” posture, soliciting food as a chick would, and males present them with a small fish, raising the crest, standing tall, and drooping the wings, all the while calling and flicking the bill upward. In the air, the male and female rise up together and fly in tandem, then quickly raise the wings in synchrony in a "V" shape, gliding and calling together for 10 seconds or so, then repeating this lovely pattern several more times. Near the nest, males sometimes make threat displays at other males, warning them away with raised crests, drooped wings, rapid head movements, and calls. Elegant Terns are probably monogamous in their mating system. Both parents incubate the egg and feed the chick. As the chicks become mobile just a few days after hatching, the adults gather them into a crèche (a tight group) but can always recognize (and feed) their own chick in these groups. The parents continue to feed their chick well after it fledges, and family groups remain together for 6 months or more after hatching. In the nonbreeding season, Elegant Terns are gregarious and often roost and feed among other seabirds, especially terns and gulls.

Conservation

Elegant Terns are still relatively common along the Pacific Coast but face numerous conservation challenges. Partners in Flight estimates a global breeding population of 180,000, rates the species a 16 out of 20 on the Conservation Concern Score, and includes it on its Yellow Watch List for birds with restricted ranges. Because Elegant Terns have very few nesting areas, they are vulnerable to disturbance by humans, dogs, cats, rats, and other natural and introduced predators. As climate change warms oceans, the distribution of Elegant Tern prey species will change, and this may also present a threat.

Credits

Burness, Gary P., Kara Lefevre and Charles T. Collins. (1999). Elegant Tern (Thalasseus elegans), 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. (2019). Longevity records of North American birds. Version 1019 Patuxent Wildlife Research Center, Bird Banding Laboratory 2019.

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

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

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

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