Anatomical Adaptations for Olfaction in the Snow Petrel

Abstract

THE accompanying photographs show the exceptional development of the olfactory apparatus of the snow petrel, Pagodroma nivea. As we have previously pointed out¹, all Procellariiformes (tube-nosed birds, or tubinares) have great olfactory equipment. The snow petrel, however, is the peer of them all. In four other tube-nosed species, Dr. Stanley Cobb² has found that the ratio of the diameter of the olfactory bulb to the diameter of the hemispheres is 29–30 per cent. He measured the snow petrel shown in Fig. 2 and found the corresponding ratio to be 34 per cent. Not only is the receptor surface area of tubinares much enlarged by an additional concha which arises from the septum and interdigitates with the olfactory concha proper (Fig. 2), but the whole nasal fossa is apparently engineered for optimum olfactory reception. Using the snow petrel as a model, I would like to point out two structures in the entry area of the tubinarial fossa which I believe are directly concerned with olfaction, yet the function of which in this respect has been obscured by having other functions attributed to them in the literature. These are the anterior concha and the anterior valve.