Shearwaters Manx' Puffinus

Based on new taxonomic insights the Manx'shearwaters are split into six different species at present:

  • Manx Shearwater Puffinus puffinus, North Atlantic.
  • Yelkouan or Levantine Shearwater Puffinus yelkouan, eastern Mediterranean Sea.
  • Balearic Shearwater Puffinus mauretanicus, western Mediterranean Sea.
  • Fluttering Shearwater Puffinus gavia, New Zealand to eastern Australia.
  • Hutton’s Shearwater Puffinus huttoni, New Zealand to eastern and South Australia.

Evolution, taxonomy and present distribution

The group consisits superficially similar, but separable forms and an almost global distribution. This has generated much debate about the taxonomic relationships between the different forms in the past. Until recently many of the species were considered to be subspecies of the Manx’ Shearwater Puffinus puffinus but rather recently the above mentioned different species are recognized. Murphy (1952) hypothesized that all species derive from one ancestral stock that origins in the present day North Atlantic and spread over the globe from there. In the same period part of an isolated brown-backed population in the present Mediterranean area (inhabited by the ancestors of modern mauretanicus and yelkouan) moved eastward through the then still exisiting passage into the Indian Ocean and colonized the New Zealand area and the Pacific Ocean. This stock gave rise to gavia and huttoni. Remains of extinct Puffinus species have been found in the Canary Islands, Balearics and New Zealand. The Lava Shearwater P. olsoni (Canary Is) appears to have been a sister species of puffinus and got extinct after 1270 AD, probably due to the introduction of rats and cats by european settlers (Ramirez et al 2010). The Dune Shearwater P. holeae (Canary Is) probably got extinct around the first human settlement on the Canary Islands (Rando & Alcover 2010). The postion of the also extinct P. nestori (Ibiza) and Scarlett's Shearwater P. spelaeus (New Zealand) is still unclear.

Osteology

Because of their close realtionship 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.


Manx Shearwater
Puffinus 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.

References