The genus
Synthliboramphus was introduced in 1837 by the German born naturalist
Johann Friedrich von Brandt. The
type genus was subsequently designated by
George Robert Gray as the
ancient murrelet. The genus name combines
Ancient Greek sunthlibō meaning "to compress" with
rhamphos meaning "bill". The genus contains five species: The first two species were formally considered
conspecific, and are sometimes separated in the genus
Endomychura.
Fossil remains of two prehistoric species are known: an undescribed
Synthliboramphus sp. 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. The parents call to the young from out at sea, and the chicks swim towards the adults who keep moving further out throughout the night.
Synthliboramphus species disperse out to sea after breeding, with northern species
migrating further south.
Synthliboramphus auks are small, with mainly black upper parts and white the short wings. These birds forage for food like other auks, by swimming underwater. They mainly eat
fish, also some
crustaceans and other small
invertebrates. ==References==