Seabird Osteology

Introduction

Seabirds live in a complicated world. They have to cope with very different situations: flying in all types of weather, walking on land, swimming in the water, digging burrows, diving under water etc. Seabirds also have to deal with a myriad of prey and food types and developed a wide range of foraging techniques tuned to their main source of food: from the small zooplankton to dead whales.  No wonder that there is a great variety of seabirds with a likewise great variety of adaptations. Some have specialized as generalists, gulls for instance, other species have developed to superspecialists such as the skimmers with their peculiar elongation of the lower mandible or the prions with their variation in bill width.
All of these adaptations are reflected by the built of the skeleton. Diving requires well developed musculature of wings or legs depending on how they propell themselves under water. That's why we see torpedo shaped bodies, short and powerfull wings or legs amomg certain divers. Large surface feeders that have to cope with the roaring forties developed amazing flying an gliding capacities and are poor divers because of their long wings. So one adaption may exclude another, but in many seabirds well balanced compromises can bee seen.

On the other hand the various seabird families have different evolutionary histories. Alcids belong to the family of the Charadriae and are related to the gulls and terns and show osteological similarities with other members of this group that are basically different from other groups. Tubenoses followed their own evolutionary track and are not related to gulls whatsoever, although some superficially look very much like them. These different evolutionary routes explain certain osteological differences, such as the well developed lachrymals in tubenoses, where these are very small and insgnificant in all Charadriae. 

On the next pages seabird osteology will be explained by general introductions and specific chapters on the different body parts and seabird families.
Although parts are treated separately, their form and function can only be understood by looking at the whole picture: the morphology of the bird in relation to is environment, its adaptations, its foraging strategies etc.

Many researchers have payed attention to the skeletal characteristics, but this information is scattered over a large number of publications. One researcher however has published a much cited work on the osteology of the petrels. In 1953 (on the day I was born!) Nagahisha Kuroda presented his thesis On the Classification and Phylogeny of the Order Tubinares, particularly the Shearwaters (Puffinus). This work forms an important inspiration for the osteology pages and his publication is much cited in the text, but there are many additions from other sources and pictures of material from my own and museum collections.