Storm-petrels are small seabirds that use their long legs to fend off the water as they snap up food from the surface. Like other procellariiforms (members of the order Procellariiformes), the storm-petrel has tubular nostrils that span almost half the length of the bill. The wings are rounded at the tip, and wing spans vary from about 12.6 inches to 22.4 inches (32 to 57 centimeters), depending on the species.
They weigh from 0.7 ounces (20 grams) to 2.9 ounces (83 grams). Their feathers are dark black or brown, and the stormpetrel’s hind end is white. Tails are squared off at the end or forked, and all storm-petrels give off a musty smell characteristic of tubenoses. Females are larger than males.
Though distributed throughout the world, storm-petrels are particularly plentiful in the Southern Ocean. While most species breed around Australasia (Australia and nearby Asian islands), five assemble around islands from Mexico to California. The birds can be found in all ocean waters.
Because they are small and dart around so quickly, it is difficult to identify the storm-petrel, so its habitats are not well known. All storm-petrels live solely in the ocean and retreat to land only during breeding season.
Crustaceans, freshwater or saltwater animals without backbones, are key foods in the storm-petrel’s diet. Depending on where the petrels are, they may supplement their diet with other marine life as well. They tend to like oily foods, and their stomachs contain the oil found in most tubenoses. This oil is used not only for warding off intruders, but as a food source for adults and chicks when other food supplies are scarce.
They feed just below the surface of the water, and though they seem to prefer eating alone, they will gather together around larger food sources such as a dead squid. Stormpetrels follow fishing vessels, eating the food scraps that spray up from the propellers.
BEHAVIOR AND REPRODUCTION
The nests are burrows, holes in the ground, which, once built, are retained each season. The same pair returns to this nest year after year. Nests are visited at night, when there are fewer predators, animals that hunt them for food. Unlike some other procellariiforms, storm-petrels do not engage in fancy courtship displays or rituals.
Storm-petrels have a variety of calls that vary between males and females. These birds tend to be solitary, alone, though some flocking occurs.
Storm-petrels are monogamous (muh-NAH-guh-mus), having only one mate, and begin breeding at four or five years of age. Breeding sites are chosen according to their location in relation to water and food. Some female storm-petrels participate in what is known as the “prelaying exodus.” During this period they feed at sea while producing their single egg, which allows them to reach the best feeding area before returning to the nest. Once back at the nest, she lays her egg within twenty-four hours.
The burrow nests are usually made by the males. The burrow is usually at the end of a tunnel, and parents take turns sitting on the egg anywhere from two to four and a half days.
This goes on typically for thirty-eight to forty-two days. The down-covered chick is hatched and attended to by its parents until it can control its own body temperature. At that point, parents visit the chick only to feed it. The chick can go six to seven days without food.
STORM-PETRELS AND PEOPLE
Seamen and fishermen have traditionally caught stormpetrels and used them as bait. This was easy to do since the birds tend to gather around fishing vessels. Native Americans were known to eat storm-petrels.
No storm-petrel is threatened, although a few of the harderto-track species need further investigation. Predators have wiped out entire colonies, but this has not yet threatened the species.