Seabird Osteology Puffinus Shearwaters

Procellariidae

Shearwaters: Puffinini
Genus Puffinus

Based on DNA analysis Puffinus Shearwaters seem to have their origin in the northern hemisphere. It is supposed that after an early split two groups from the ancestral shearwater stock followed their own evolutionary track. The Manx', Audubon's and Little Shearwaters forming genus Puffinus in the northern hemisphere and another group, the so called 'southern' shearwaters (Brooke 2004), for which recently the generic name Ardenna has been proposed and adopted by many. The boundaries between the species of Puffinus are not so clear cut as in the southern shearwaters.
From a single ancestral stock in the former Tethys Sea (now the northern Atlantic) in times when the continents were not yet connected they may have spread over the world via the then submerged isthmus of Panama and what is now the Mediterranean Sea and the Red Sea.

Christmas Shearwater

An ancient split from the to the complexes treated below is the all dark Christmas Shearwater. In size and structure it is very similar to the 'Manx Shearwaters'. Unlike the other lesser shearwaters it is a non-burrowing species from the Hawaiian Chain and other central Pacific islands.

Christmas Shearwater Puffinus navitatis, Pacific Ocean.

The assimilis and lherminieri complex

This group embraces a number of five highly variable species with a global distribution, roughly divided in a ‘lherminieri–tribe’ and the ‘assimilis-tribe’. These groups are subject to taxonomic discussion and this will sooner or later lead to a revision of the taxonomic status of the species involved.
The lherminieri-group counts about 15 (sub)species

Mascarene Shearwater Puffinus atrodorsalis, western Indian Ocean ('species' of unclear status)

Heinroth's Shearwater Puffinus heinrothi, Bismarck Sea to Solomon Is.

Galapagos Shearwater P. subalaris, Galapagos Is.

Audubon's Shearwater Puffinus lherminieri, a range of subspecies in all oceans

Audubon’s Shearwater P. l. lhermienieri, Bahamas, West Indies.

P. l. loyemilleri, Caribbean south to Venezuela

P. l. temptator, Comoros.

P. l. colstoni, Aldabra.

P. l. nicolae, Amirantes, Sey, Maldives, Chagos Is.

Baillon's Shearwater P. l. bailloni, Mascarene Is.

Bannerman’s Shearwater P. l. bannermani, Bonin and Volcano Islands.

P. l. gunax, New Hebrides.

P. l. dichrous, Fiji, Phoenix, Line Is, Marquesas, Gambier, Society Is, Samoa, Tokelau.

Persian Shearwater P. l. persicus, Kuria Maria Is. and Socotra

Boyd's Shearwater P. l. (a.) boydi, Cape Verde Islands (sometimes treated as a ssp. of assimilis)

Little ShearwaterPuffinus assimilis baroli
Lanzarote, Canary Islands

Little Shearwater Puffinus assimilis with subspecies in all three major oceans

P. a. baroli, Azores, Desertas, Salvages, Canary Is.

P. a. tunneyi, Amsterdam and St. Paul’s Islands and off Western Australia.

P. a. assimilis, Lord Howe and Norfolk Islands.

P. a. kermadecensis, Kermadec Is.

P. a. haurakiensis, off east coast North Island, New Zealand.

P. a. elegans, Chatham and Antipodes Is,Tristan da Cunha Group and Gough I.

P. a. myrtae, Rapa and Austral Is.

The ‘Manx shearwaters’

This group is of a great taxonomic complexity and with an almost global distribution. Until recently many of the species were considered to be subspecies of the Manx’ Shearwater Puffinus puffinus. Based on new taxonomic insights eight different species are recognized at present:

Manx Shearwater Puffinus puffinus, North Atlantic.

Yelkouan or Levantine Shearwater Puffinus yelkouan, eastern Mediterranean Sea.

Balearic Shearwater Puffinus mauretanicus, western Mediterranean Sea.

Townsend’s Shearwater Puffinus auricularis, eastern Pacific, Mexican coast.

Newell’s Shearwater Puffinus newelli, Pacific, Hawaiian waters.

Black-vented Shearwater Puffinus ophistomelas, eastern Pacific, Mexican and US West Coast

Fluttering Shearwater Puffinus gavia, New Zealand to eastern Australia.

Hutton’s Shearwater Puffinus huttoni, New Zealand to eastern and South Australia.

Identification of the different species and subspecies of the Manx group by their skull and skeleton is very difficult, if not impossible. There is no comprehensive key to identify the bones of these shearwaters. They are very similar is size and structure, though some species average slightly larger or smaller than other. There is much overlap and individual variation within the species obscures the boundaries between the species. The location of collection might give an indication, but is not a reliable parameter since many species of this group are highly migratory and have been found in other than their native region, such as P. puffinus in Australia, New Zealand and the Pacific coast of North America. For a positive identification other morphological characteristics are indispensable. Only the the differences between heads and bills of the Hutton's and Fluttering Shearwater, two very similar birds sharing the same region, have been studied extensively.

Bill length (average; range)
Species	Male	Female
Species	Male & Female
P. navitatis	32.3 – 33.4	?
P. puffinus	34.9; 33.0 - 38.0	34.3; 31.0 - 36.0
P. yelkouan	35.7; 32 -38
P. mauretanicus	38.5; 35 - 43
P. auricularis	31.9; 30.6 - 34.4	31.6; 28.9 - 34.4
P. newelli	33.4; 32.3 - 35.5	32.9; 30.2 -34.8
P. ophistomelas	37.5; 35.4 - 41.2	36.9; 34.2 - 37.8
P. gavia	34.1; 30.9 - 37.4	32.5; 29.1 - 35.1
P. huttoni	36.4; 35.4 - 38.0	36.4; 31.9 - 37.4

	Manx ShearwaterPuffinus puffinus Skomer, Wales, UK Culmen: 33.5 mm; total: 80.1 mm; adult, unsexed adult.
	Yelkouan or Levantine Shearwater Puffinus yelkouan Samos, Greece Culmen: 32.5 mm; total: 76.7 mm; unsexed adult
	Balearic Shearwater Puffunis mauretanicus Villanova i Geltru, Spain Culmen: 38.8 mm; total: 89.2 mm, adult male
	Hutton's Shearwater Puffinus huttoni Baylyss Beach, North Island, New Zealand Culmen: 36.3 mm; total:80.5 mm; adult female
	Fluttering Shearwater Puffinus gavia Kaikoura, South Island, New Zealand Culmen: 31.2 mm; total: 77,8 mm; unsexed adult.
	Black-vented Shearwater Puffinus ophistomelas Location unknown. Culmen: 33.1 mm; total: 81.6; adult, unsexed adult.