Procellariidae

Shearwaters: Puffinini

Osteology

Among the tubenoses the shearwaters show the greatest variety of flight and diving behaviour. As a result also a great variety of anatomical adaptations is found within this group. Kuroda (1953) made an extensive study of this. As a general rule the more aerial species in which a gliding flight dominates are not very well adapted to diving (not diving often and/or only to limited depths, such as all Calonectris and Thyellodroma (Wedge-tailed and Buller’s Shearwater) On the other end of the spectrum there are the Puffinus (Manx’ and Audubon’s/Little Shearwaters) and the champion divers of the subgenus Neonectris (Sooty and Short-tailed Shearwaters). Midrange in this respect are the three species of the subgenera Ardenna (Great Shearwater) and Hemipuffinus (Fleshy- and Pink-footed Shearwater). Wind conditions influence the picture in individual cases.
 

Skull
Skulls are pictured in the species section. Shearwater skulls are in general light built with rather long bills, but there is a considerable variation in this respect. The lachrymals are not fused. The lachrymals and the palate are connected to each other by a tiny bone, which is missing in most cleaned skulls. As in any bird skull the pterygoids and quadratums form a flexible basis for the joint with the lower mandible, alowing passage to quite large preys.

 

Sternum, coracoid and furcula
The more aerial species in which a gliding flight dominates have relatively small, short, and ‘square’ breastbones. This implicates rather small and short flight musculature more suited for static forces. The diving species have rather large and elongated brest bones to provide a basis to the large and longer breast muscles that are needed for underwater propulsion. Coracoids and furcula are lighter built in the aerial species compared with the diving species.

 

Wing
The wing of a shearwater consists of 13 bones: the usual set of humerus, ulna, radius, two carpal bones, metacarpus and four digital bones, including the alula. An extra, small sesamoid bone is found in the elbow as an extension to the ectepicondular process. It forms a supporting strut for the patagial fan in the outstretched wing. This bone (sometimes two) is also found in other petrel groups, but not in all) The built of the wing bones also reflect the variation in habits. The shape of the humerus shows the difference most clearly: in aerial species light built, proportionally long and with a more more rounded shaft. Divers have stronger bones, flattened to provide better aquadynamics and are relatively short. Ulna and radius show a similar difference. In the diving species the hand wing (metacarpus and phalanges) is slightly longer to the arm parts (humerus, ulna and radius) while in the aerial species the arm part is longer. Species with intermediate behaviour have also intermediate characteristics.

Leg
Shearwater legs also show the abiltiy of diving very well. In the aerial species the femur is realtively long and straight and in the diving species shorter and more curved. The processus rotularis of the tibia is the most prominent feature corresponding with the underwater habits: short in species that dive only to limiteg depths long in the diving species. In Calonectris this process adds about 10-11% to the efective length (between the articular surfaces). In the diving species we find values of 21-24% > see table. The tarsus in diving species is flattened laterally and more round in the aerial species.



 

Evolution and taxonomy

 

 

Pelvis and legs
 
Literature
  • Brooke, M., 2004, Albatrosses and Petrels across the World, Oxford University Press, Oxford, UK
  • Burg, T.M. & Croxall, P, 2004, Global population structure and taxonomy of the wandering albatross species complex, Molecular Ecology 13, 2345-2355, Blackwell Publishing Ltd
  • Dénes, F.V. & Silveira, L.B. 2007, Cranial Osteology and taxonomy of albatrosses of genus Diomedea Linnaeus, 1758 and Thalassarche Reichenbach 1853 (Procellariformes: Diomedeidae), Pap. Avulsos Zool., Vol. 47 no. 3. Sao Paulo
  • De Roy, T; Jones M.; Fitter, J., 2008, Albatross: their world, their ways. Firefly Books Ltd, Richmond Hill, Ont. Canada
  • Dubois, P., Janre, P. & Jouventin, P., 2005, Ten polymorphic microsatelite markers in the wandering albatross Diomedea exulans, Molecular Ecology Notes, Blackwell Publishing
  • Fisher, M.L., 1970, The Albatross of Midway Island, Southern Illinois Univ. Press, Carbondale, USA
  • Huin, N.; Prince, P.A., Diving behaviour of the Grey-headed Albatross, Antarctic Science 9:3:243-249 Cambridge University Press
  • Jameson, W, 1958, The Wandering Albatross Rev. Ed., Doubleday & Co., Inc., New York, USA
  • Murphy, R.C, 1936, Oceanic Birds of South America, Macmillan Comp. & Am. Mus. of Nat. Hist., New York
  • Nunn, G.B.; Cooper, J.;Jouventin, P.; Robertson, C.J.R. & Robertson, G.G. 1996. Evolutionary relationships among extant albatrosses (Procellariformes Diomedeidae) established from complete cytochrome-b gene sequences. The Auk, 113:784-801
  • Penhallurick J. & Wink M., 2004, Analysis of the taxonomy and nomenclature of the Procellariiformes based om complete nucleotide sequences of the mitochondrial cytochrome-b gene, Emu, 2004, 104; 125-147.
  • Prince, P.A., Huin N., Weimerskirch H., 1994, Diving depths of Albatrosses, Antarctic Science 6:3:353-354 Cambridge University Press
  • Rheindt, F.E. & Austin, J.J. 2005. Major and conceptual shortcomimgs in a recent taxonomic revision of the Procellariiformes - A reply to Penhallurick & Wink 2004, Emu, 105; 181-186.
  • Robertson, C.J.R & Nunn, G.B. 1998 Towards a new taxonomy for the albatrosses. In Robertson, G. & Gales, R. (eds), Albatross Biology and Conservation Surrey Beatty & Sons, Chipping norton, NSW, Australia, 13-19. 
  • Tickell, W.L.N., 2000, Albatrosses, Pica Press, Sussex, UK
  • Warham, J., 1990, The Petrels, their Ecology and Breeding Systems, Academic Press, London, UK
     

    Photos
    Bones: E. Soldaat

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