Northern storm petrel

Northern storm petrels are seabirds in the genus Hydrobates in the family Hydrobatidae, part of the order Procellariiformes. The family was once lumped with the similar austral storm petrels in the combined storm petrels, but have been split, as they are not closely related. These smallest of seabirds feed on planktonic crustaceans and small fish picked from the surface, typically while hovering. Their flight is fluttering and sometimes bat-like.

The northern storm petrels are found in the Northern Hemisphere, although some species around the Equator dip into the south. They are strictly pelagic, coming to land only when breeding. In the case of most species, little is known of their behaviour and distribution at sea, where they can be hard to find and harder to identify. They are colonial nesters, displaying strong philopatry to their natal colonies and nesting sites. Most species nest in crevices or burrows, and all but one species attend the breeding colonies nocturnally. Pairs form long-term, monogamous bonds and share incubation and chick-feeding duties. Like many species of seabirds, nesting is highly protracted, with incubation taking up to 50 days and fledging another 70 days after that.

Several species of storm petrel are threatened by human activities. One species, the Guadalupe storm petrel, is thought to have gone extinct. The principal threats to storm petrels are introduced species, particularly mammals, in their breeding colonies; many storm petrels habitually nest on isolated mammal-free islands and are unable to cope with predators such as rats and feral cats.

Up and down! - up and down!
From the base of the wave to the billow’s crown,
And amidst the flashing and feathery foam
The stormy petrel finds a home, -
A home, if such a place may be
For her who lives on the wide, wide sea.

O’er the deep! - o’er the deep!
Where the whale and the shark and the sword-fish sleep, -
Outflying the blast and the driving rain,
The petrel telleth her tale — in vain;
Yet he ne’er falters, - so, petrel, spring
Once more o’er the waves on thy stormy wing!

The family Hydrobatidae was introduced with Hydrobates as the type genus by the Australian born ornithologist Gregory Mathews in 1912. The background is complicated as the family Hydrobatidae had originally been introduced in 1849 with Hydrobata as the type genus by the French zoologist Côme-Damien Degland. Hydrobata had been erected in 1816 for species in the dipper family Cinclidae by the French ornithologist Louis Pierre Vieillot. In 1992 the International Code of Zoological Nomenclature (ICZN) suppressed the genus Hydrobata Vieillot, 1816. Under the rules of the ICZN the family Hydrobatidae Degland, 1849 thus became unavailable as the type genus had been suppressed. This cleared the way for the family Hydrobatidae introduced in 1912 by Mathews.

The genus Hydrobates was erected in 1822 by the German zoologist Friedrich Boie. He listed two species but did not specify a type. In 1884 Spencer Baird, Thomas Brewer and Robert Ridgway designated the European storm petrel as the type species. The genus name combines the Ancient Greek hudro- meaning "water-" with batēs meaning "walker".

In the past two subfamilies, the Hydrobatinae and Oceanitinae, were recognized within a single large family Hydrobatidae, but this has since been split with the elevation of the Oceanitidae to family status. The Oceanitidae, or austral storm petrels, are mostly found in southern waters (though Wilson's storm petrel regularly migrates into the Northern Hemisphere). The Hydrobatidae, or northern storm petrels, are largely restricted to the Northern Hemisphere, although a few visit or breed a short distance south of the equator. The family Hydrobatidae originally included two genera Hydrobates and Oceanodroma. Cytochrome b DNA sequence analysis suggested that the family was paraphyletic and more accurately treated as two distinct families. A few fossil species have been found, with the earliest being from the Upper Miocene. In 2021, the IOC merged Hydrobates and Oceanodroma into the single genus Hydrobates, as the family was paraphyletic as previously defined.

The following cladogram shows the results of the phylogenetic analysis by Wallace et al. (2017).