igS WHALES 



depends very much on a number of factors, of which space and food 

 resources are the main considerations. If the food supply is profuse over 

 a wide area, biting and butting abate, but ^vhen there is keener competi- 

 tion for food, the number of attacks increases greatly. Horses feeding from 

 a trough, for instance, are much more aggressive to other horses than when 

 they are grazing. In general, animals in captivity are more aggressive 

 than animals in their natural state, though some domestic pets seem to 

 have lost all traces of assertiveness. 



The most important data on the social behaviour of Cetaceans are once 

 again based on observations of the Bottlenose Dolphins in Marineland. 

 Apparently, these animals assert their social position by lashing out with 

 their tails, by pushing with their snouts, and even simply by adopting a 

 threatening attitude. The White-beaked Dolphins of Marineland in 

 California often show weals inflicted by a congener placed higher in the 

 hierarchy (see Fig. loo). While their social disputes are generally fairly 

 mild, dolphins will occasionally inflict terrible gashes on their fellows, 

 particularly when new^ animals are added to the tank. The ne\vcomers 

 are apparently expected to fight their way into the herd -just like 

 students who have often to undergo somewhat vmpleasant initiation rites. 



From observations made in Alarineland, it appeared that male Bottle- 

 nose Dolphins observe a very strict hierarchical order, mainly based on 

 size. Cows never fight amongst themselves if one or more bulls are present. 

 In the absence of a bull, however, they will assert their place in the 

 hierarchy, the biggest cow usually taking first place, etc. 



Naturally, it is almost impossible to investigate whether non-captive 

 Cetaceans behave in the same way, since to do so would involve picking 

 out individuals from a mass of animals swimming about under the surface. 

 All we can say with certainty is that whales and dolphins very often show 

 scars or weals inflicted by their fellows. In Sperm Whales, for instance, the 

 skin is often marked by a number of parallel stripes at intervals corres- 

 ponding precisely with the gaps between their teeth. I myself was shown 

 such stripes on Ziphiids of the genus Berardius at the Japanese whaling 

 station Ayukawa, and my colleague Omura told me that he had seen 

 them repeatedly. Similar scars have often been found on porpoises, and 

 particularly on Common Dolphins, Bottlenose Dolphins, Risso's Dolphins 

 and Rough-toothed Dolphins, where they occur also in the females of the 

 species. 



Many healed fractures of ribs and other bones, e.g. vertebral processes, 

 which are commonly found on Cetacean skeletons, must also have been 

 caused in the same way. My book on the Cetaceans (1936) contains a list 

 of seventy-t^vo such fractures found both in recent and also in fossil 

 Cetaceans, but meanwhile the number of known cases of fracture has 



