Hydrobatidae Northern Storm-Petrels
Version: 1.0 — Published March 4, 2020
Introduction
These storm-petrels of the northern oceans have shorter legs and skulls and longer wings than those of their cousins in the Oceanitidae. They journey to the other ends of Earth in the nonbreeding season, but then find their way back to the home colony where they raise a single chick in a burrow. The chicks are remarkable balls of fluff, the downy feathers many centimeters thick, and they have the distinctive musky smell common to most in this order. These scents help guide the birds to their home burrows in the dark of night, which is a valuable trait since most visit their isolated island colonies only at night to avoid predation by gulls or frigatebirds.
Habitat
During most of the year, hydrobatids are found far from shore, out over open ocean. When breeding, they generally nest on small isolated islands off the coast where there are rock crevices to nest in or soil to burrow in.
Diet and Foraging
Storm-petrels flutter low over the water and pluck zooplankton, small fish, squid, and small crustaceans from the water’s surface with their bills. Though they sometimes sit on the water in rafts, they do essentially all their foraging from the wing.
Breeding
Storm-petrels are monogamous and may maintain a long-term pair bond in which a mated pair meets at the same nest burrow year after year. Most storm-petrels nest in a rock crevice or burrow, excavating the latter if necessary. The female lays a single egg with a mass of 20% to 30% of her body weight. Males and females contribute equally to parental care, from burrow construction/maintenance, through incubation, brooding, and provisioning of the chick. Incubation takes about 50 days, and the parents incubate in bouts of a couple days up to a week or so in length. The chick is usually brooded for the first week post-hatch, and the parents manage to feed it nightly for much of its development. Still, it doesn’t reach fledging age until about two months post-hatch. When the chick leaves, it ventures out to sea on its own.
Conservation Status
Like many other seabirds, storm-petrels have suffered from habitat destruction and the introduction of mammalian predators like rats and cats, and six species (40%) of northern storm-petrels are at risk (2 NT, 2 VU, 1 EN, 1 CR(PE)). The Guadalupe Storm-petrel Oceanodroma macrodactyla, restricted to nesting on the island of Guadalupe off the Mexican coast, is listed as critically endangered, and possibly extinct; it has not been sighted since 1912.
Systematics History
Hydrobatidae is part of the order Procellariiformes. Traditionally, this family had contained two sub-groups, the northern-breeding Hydrobatinae and the southern-breeding Oceanitinae. Recent molecular phylogenetic studies indicate, however, that Hydrobatinae and Oceanitinae are not actually sister taxa and are part of a polytomy with Diomedeidae (Kennedy & Page 2002; Hackett et al. 2008). Additional morphological studies suggest that the northern storm-petrels are more closely related to petrels than they are to albatrosses or southern storm-petrels (Forbes 1882, Mayr 2009). Although these relationships will no doubt be further clarified in the future, the splitting of the storm-petrels into two families seems very well established.
Conservation Status
Least Concern |
44.4%
|
---|---|
Near Threatened |
16.7%
|
Vulnerable |
22.2%
|
Endangered |
11.1%
|
Critically Endangered |
5.6%
|
Extinct in the Wild |
0%
|
Extinct |
0%
|
Not Evaluated |
0%
|
Data Deficient |
0%
|
Unknown |
0%
|
Data provided by IUCN (2023) Red List. More information