Everything about Pelecanoididae totally explained
The
diving-petrels are
seabirds in the
bird order Procellariiformes. There are four very similar species all in the family Pelecanoididae and genus
Pelecanoides Lacépède, 1799. They are
auk-like small
petrels of the southern oceans. The resemblances with that unrelated group are due to
convergent evolution, since both
families feed by pursuit diving, although some researchers have in the past suggested that the similarities are due to relatedness. Amongst the Procellariiformes the diving petrels are the family most adapted to life in the sea rather than flying over it, and are generally found closer inshore than other families in the order. Of the four species two, the
Peruvian Diving-petrel and the
Magellan Diving-petrel, have highly restricted ranges around
South America's coasts, whilst the
Common Diving-petrel and the
South Georgia Diving-petrel range widely across the southern oceans, breeding on islands off New Zealand, sub-
Antarctic islands in the
Indian Ocean, and islands in the south
Atlantic (like
Tristan da Cunha).
Diving-petrels are
plankton feeders, taking mostly
crustacean prey such as
krill,
copepods and the
amphipod Themisto gaudichaudii, also taking small fish and squid. They have several adaptations for obtaining their prey incliude short powerful wings, a gular pouch for storing food, and their
nostrils open upwards rather than forward pointing as it's in other
tubenoses.
These
birds nest in colonies on islands. One white egg is laid in a burrow in turf or soft soil. They are nocturnal at the breeding colonies. It has a long period of parental care (around 45 - 60 days) in the burrow, but once the chick
fledges out to sea it's on its own.
Diving-petrels are amongst the world's most numerous birds, with Common and South Georgia Diving-petrels numbering several million pairs each. The Peruvian Diving-petrel, on the other hand, is threatened by
guano extraction,
introduced species and
climate change, and is listed as an
endangered species.
The four species are:
The
evolution and systematics of these birds isn't too well researched. Several populations were described as distinct species and while most of them are only subspecies, some may indeed be distinct. The prehistoric
fossil record was long limited to very fragmentary remains described as
P. cymatotrypetes found in Early
Pliocene deposits of
Langebaanweg,
South Africa; while this bird apparently was close to the Common Diving-petrel, no members of the genus are known from South African waters today.
In 2007, a
humerus piece from
New Zealand was described as
P miokuaka. This was found in Early/Middle
Miocene deposits and just as may be expected, it far more resembles diving-petrels than any other known bird, but presents a less
apomorphic condition.
Footnotes
Further Information
Get more info on 'Pelecanoididae'.
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