282 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1954 



arrive first and take up their territories ; then the cows come and give 

 birth to their pups a few days or even a few hours after their arrival. 

 Each bull collects a harem of females over which he keeps watch, 

 driving away any rivals that may try to poach on his territory. While 

 the cows are nursing they go to sea to lish, and return every day or so 

 to feed their pups, but the bulls remain at their posts for about 3 

 months without feeding. At the end of the season the old bulls move 

 off to their winter quarters south of the Aleutians and in the Gulf of 

 Alaska, but the cows, the pups, and the young bulls go much farther, 

 and winter at sea as far south as the latitude of southern California, 

 successfully making a journey of 3,000 miles across the open ocean 

 and not by following the coastline. Many other kinds of seals, though 

 not all, have similar migrations perhaps on a rather smaller scale, 

 though as yet little is definitely known of them. 



Many kinds of whales make regular seasonal migrations over great 

 distances. In the southern oceans the gigantic blue whale, the fin 

 whale, the humpback and others perform regular journeys during the 

 antarctic summer, to the far south, where they feed upon the rich 

 plankton that swarms in those cold seas at that time of year. And 

 then they depart to the north, and spend the winter in temperate and 

 subtropical seas, where they feed very little or not at all while their 

 young are born and nursed through the early weeks of life. In these 

 migratory journeys whales cover many thousands of miles far away 

 from any land so that there is no possibility of obtaining any guid- 

 ance by following the lines of a coast. 



The migrations of the sea mammals thus differ from those of ter- 

 restrial ones, which are not only limited by topographical features of 

 the land but might also be guided by the recognition of landmarks. 

 The marine mammals can have no such influences to guide them on 

 their journeys. 



How then do they do it? Frankly, we just do not know; none of 

 the many theories that have been put forward to explain such migra- 

 tions seems to me to be adequate. People w^ere once content to say 

 "instinct" and leave it at that, but the expression was no more than a 

 confession of ignorance. The invocation of the Coriolis force has 

 been shown to be untenable as an explanation of the orientation of 

 birds during migration ^ ; it would be even less applicable to the more 

 slowly moving migrating mammals. 



Much thought has been given to the possibility that migrating birds 

 navigate by observing the position of the sun or other heavenly bod- 

 ies ; if birds can navigate by that means, why not mammals ? It seems 

 to me that there has been some confusion of thought here. If an 

 animal is to navigate successfully it must have a knowledge of where 



* See Matthews, G. V. T., Direction-finding in birds, Discovery, May 1953, 

 p. 149. 



