Habitat
Fork-tailed Storm-Petrels nest on remote islands in the North Pacific, where they use crevices among rocks, talus slopes, sod, or roots or make burrows in soft soil. Their burrows in tundra habitats have plants such as sedges, grasses, or wild celery around them. They sometimes reuse old burrows of Tufted Puffins and often nest near other seabirds, including Leach’s Storm-Petrels. When nesting, these birds tend to forage within about 50 miles or so of their nest sites. During the nonbreeding season, Fork-tailed Storm-Petrels forage over a large swath of the North Pacific, usually far from shore, in cold (45–48°F), deep water, often beyond the continental shelf and typically north of 40°N latitude.
Back to topFood
Fork-tailed Storm-Petrels prey on tiny crustaceans and fish, which they hunt mostly in flight. They course low over the sea surface, then stall to dip down and seize prey in the bill, often dropping their feet and pattering on the sea surface to maintain position. They also sometimes dive down, as deeply as 2 feet, in pursuit of prey. They feed at night as well as during the day. They use their excellent sense of smell to find productive areas for foraging, such as at floating carcasses of dead animals or at fishing operations. Their prey include squid; zooplankton including amphipods, copepods, decapods, and euphausiids; and small fish such as capelin, greenling, rockfish, and sablefish. They feed mostly fish to their young.
Back to topNesting
Nest Placement
Nests in dry, enclosed locations on marine islands, such as abandoned puffin burrows, under clumps of vegetation, in rock and lava crevices, in talus slopes, under logs, or between tree roots. Where soil is loose enough, adults sometimes excavate a nest burrow using their bill and feet.
Nest Description
Nests are minimal, sometimes made of grass, sedge, or other plants, but most pairs build no nest structure. The females lay their eggs directly on soil or stone. Burrows are typically between 13 and 23 inches deep, with the entrance 3.9–4.7 inches tall and 3.7–.5.5 inches wide.
Nesting Facts
| Egg Description: | Dull white, often with blunt end encircled by ring of dark purplish-red spots. |
| Condition at Hatching: | Covered with long gray down, eyes closed. |
Behavior
When they arrive back at their breeding islands, Fork-tailed Storm-Petrels typically re-partner with their mate of the previous nesting season. They begin courtship immediately with swift aerial chases and much calling above the nest site. Males lead females toward the nest site in flight and call from the entrance or from inside the nest. Pairs vocalize and preen one another extensively at the nest site, where they may spend several days without venturing out to feed. Many pairs use the same nest site for several years in a row. This species appears to be monogamous in its mating system. Females lay just one egg, and both adults take turns incubating the egg and provisioning the chick. Once the chick has fledged, it leaves the burrow on its own. During the nonbreeding season, Fork-tailed Storm-Petrels are usually seen in small flocks that feed together and rest on the sea surface.
Back to topConservation
The Fork-tailed Storm-Petrel is widespread and abundant, but there is no information on its population trends. Partners in Flight estimates a global breeding population of 4 million birds and rates the species a 9 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. This species is vulnerable to oil spills, which foul the plumage. The species' tendency to consume floating oil from marine animals may make it especially vulnerable to petroleum poisoning. Like other seabirds, Fork-tailed Storm-Petrels ingest small bits of plastic that float on the ocean’s surface. This plastic pollution tends to concentrate pollutants that can poison the birds; the plastic pieces also accumulate in the birds' stomachs.
Back to topCredits
Dee Boersma, P. and Mónica C. Silva. (2001). Fork-tailed Storm-Petrel (Oceanodroma furcata), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.
Howell, S. N. G. (2012) Petrels, albatrosses, and storm-petrels of North America. Princeton University Press, Princeton, New Jersey.
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. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.
Partners in Flight (2017). Avian Conservation Assessment Database. 2017.
Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.