Wildlife

Seabirds of Alaska Maritime National Wildlife Refuge

Fork-tailed Storm-Petrel (Oceanodroma furcata)
Leach’s Storm-Petrel (O. leucorhoa)

These petrals are among the smallest and most delicate of birds that spend much of their life on the open ocean.

RANGE

Both are found throughout the North Pacific and in Alaska from the western Aleutians through the Gulf of Alaska and commonly nest in mixed colonies. Fork-tailed storm-petrels also nest in the Kuril Islands and south to northern California.

Leach’s storm-petrels have a wider range, breeding southwest to northern Japan and southeast to Baja California. They range widely in winter, becoming common in the waters of the central Pacific. In the Atlantic, colonies are known from northeast United States to Labrador, Iceland, the Faroes, and the British Isles.

PLUMAGE

The pale gray feathering of the fork-tailed is unique among the typically dark storm-petrels.

NOCTURNAL HABITS

Storm-petrels are strictly nocturnal on their nesting colonies, always arriving at their nest site before dawn and leaving after dark This minimizes encounters with gulls and other avian predators that hunt in the daylight.

NESTING

Storm-petrels nest underground, out of sight of avian predators. Fork-tailed storm-petrels usually nest in crevices between talus or in rocky soil. The Leach’s dig burrows in soft grassy soil. Each can use the other’s nesting habitat to some extent.

EGG

Single. Incubation duties are shared in shifts of several days, allowing the adults to forage over a vast area, even during nesting.

FEEDING RANGE

They find their food far from their breeding colonies. The fork-tailed storm-petrel feeds over the outer continental shelf and adjacent deep ocean. Leach’s typically feed only over the deep ocean.

FOOD

Storm-petrels seize various zooplankton, small fish, and squid as they sit or patter over the surface of the water. Zooplankton or squid are common in their diets, but in some parts of the Gulf of Alaska and Bering Sea, the birds may depend on fishes such as capelin and sandlance.

DANGERS ON LAND

Storm-petrels are highly vulnerable to non-native, introduced predators such as foxes, rats, and other rodents that can easily dig out or enter their underground nest burrows. Islands where foxes were introduced here, lost their storm-petrel colonies. The birds have successfully returned to nest after the alien foxes died out or were removed.

Storm-petrels are also vulnerable to human visitors walking over their nesting burrows and crushing them or to dogs digging them out. Introduced cattle also trample and collapse the fragile burrows, causing desertion even of nearby burrows that escape destruction.

DANGERS AT SEA

At sea at night, storm-petrels are frequently attracted to lights on ships and occasionally alight on the decks where they are easily captured.

POPULATION ESTIMATES

Storm-petrels require intensive work to count accurately because of their underground nests and nocturnal movements. Estimates range up to 6 million for each species in the state or about one fifth of all seabirds in Alaska. Single colonies number in the hundreds of thousands.

Last updated:September 8, 2008