 from the Late Miocene or Early Pliocene (c. 5 mya) of Cedros Island, Mexico, and "Synthliboramphus rineyi" from the Late Pliocene (around 3.5-2 mya) San Diego Formation of the southwestern USA.These birds breed in colonies, their eggs being laid directly amongst tree roots or in rock crevices.They are nocturnal on the breeding grounds, presumably to reduce predation, and for the same reason the precocial young are never fed at the nest, being taken to sea a couple of days after hatching.