The final members of this subfamily are the little Dove Petrels (Prion), of which some four species are recognized; all are inhabitants of the southern oceans. About twelve inches long, the upper surface is ashy blue, darker on the head and under the eye, and white below, while there is a very distinct black V-shaped band running from the wrist-joint along the radial portion of the wing to and across the rump, which is very conspicuous when the bird is flying. The several species are mainly distinguished by the width of the bill. The common Dove Petrel (P. Desolatus) is perhaps the best known, being not uncommon in the South Atlantic and Antarctic seas. They fly in small flocks, and Kidder notes that they use first one wing and then the other, producing a peculiar irregularity of flight, that leads them to be often mistaken for shore-birds. They are rather wary, not feeding on the scraps from a ship, but attending the whales to feed on what drops from their mouths, whence they are often called Whale-birds by the sailors and others. They breed on Kerguelen Island, making their burrows near the seashore, in lowland, under stones, or in the stony ground, and are strictly nocturnal in their habits.