BEHAVIOUR igi 



Herds of zebras are known to join other herd animals (e.g. antelope 

 and buffalo), and the same may be true of Fin Whales also. On 24th 

 June, 1955, A. Vermeulen, first mate on M.S. Oberon (K.N.S.M.) reported 

 that, at 39° N 73° W, he observed a school of about fifty Fin Whales 

 swimming in a north-easterly direction. The animals, apparently on their 

 migration to the north, were accompanied by hundreds of dolphins. 



Common Dolphins, Bottlenose Dolphins, False Killers, or dolphins of 

 the genera Prodelphinus, Lagenorhynchus, Orcaella and Steno occur 

 in very large, mixed and apparently leaderless schools. The existence of 

 mixed schools of dolphins, i.e. schools containing bulls, cows and calves 

 of all ages, has been established on many occasions either during mass 

 strandings or during mass catches (see Chapter i). Though dolphins have 

 often been seen in fairly or even very small schools, schools of about 1,000 

 strong are by no means rare. In 1955 Tomilin reported that he had 

 seen a school of Black Sea Dolphins from the air, which he estimated at 

 roughly 100,000 animals. Such schools must be considered exceptional, 

 however, and are probably restricted to the breeding grounds of the fish on 

 which the dolphins feed. If food becomes scarce, these large schools 

 break up into smaller ones again. Schools of Little Piked Whale, Hump- 

 back Whale, Cuvier's Whale, Risso's Dolphin and of some River Dolphins 

 are usually smaller than 100, and generally consist of ten to twenty 

 animals, the schools being mixed, as far as is known. Boutus live in schools 

 of from three to six, and are sometimes found alone, while Rough Toothed 

 Dolphins of the genus Sotalia have been seen in schools of from three to 

 twenty. 



Greenland and Blue Whales usually live alone or in small family groups 

 of bull, cow and calf, though Greenland Whales are thought to combine 

 into schools where food is plentiful. Blue Whales, too, live solitary or 

 restricted lives in the Arctic and Antarctic, but in their winter quarters 

 they are said to combine into larger groups. Capt. Mörzer Bruins reported 

 that, on 23rd September, 1953, at ii°i5'N 6o°2o'E, i.e. in the Indian 

 Ocean, he met a school of thirty to fifty Blue Whales, spread over an area 

 of ten miles. Within the school itself, smaller groups of three to four 

 animals could be distinguished. 



The Sei Whale appears to lead a more solitary existence and is rarely 

 met in larger groups, while the Pigmy Sperm Whale seems to avoid his 

 fellows almost completely. The Gangetic Dolphin, too, does not apparently 

 like its congeners, though inore than one individual may share the same 

 creek. 



Amongst terrestrial animals (e.g. mountain zebras, donkeys, sheep and 

 goats), we often find separate herds of males and females. The female 

 herd, which includes immature young males, is sometimes led by a strong 



