Petrels, shearwaters and diving petrels | Procellariidae

Pijlstormvogels | Petreles y pardelas

Both nostrils open into a single tube on top of the bill. The flight is distinctive: just above the sea the bird rises at an angle on the wind and then glides back down into the trough on stiff wings, so that the dark upperside and the pale underside flash by turns; the rhythm of those arcs differs between species and at a distance is often the only thing to go on. Food is snatched from the surface in flight or picked up while swimming, and some species row down with half-folded wings tens of metres deep after fish and squid. Carcasses and waste from fishing boats draw large groups that squabble noisily over them. Off the colony the birds gather towards evening in floating rafts on the water; they breed in a self-dug burrow or a rock crevice, and young birds leave for the sea alone at night, on inhabited islands easily disoriented by artificial light. Outside the breeding season many species range across whole ocean basins and cross the equator, so that birds from southern breeding grounds lie off these coasts in midsummer.