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which, when heard at night, may sound 

 scary to the uninitiated. 



When a mother falls asleep in the shal- 

 lows, the faUing tide lowers her slowly to- 

 ward the sea bed. Often her flippers dig 

 deep into the sand before she wakes up 

 and moves. This leaves obvious flipper 

 impressions, which, if the day is cakn, sur- 

 vive the falling tides so we often can walk 

 out to where the whale was sleeping and 

 admire her flipper prints. As we stand be- 

 tween them on the vast, draining tide flats, 

 the scale of these marks is an eloquent 

 statement of just how big the whales are. 



Aside from these tranquil activities, the 

 whales are engaged in courtship and mat- 

 ing when in residence at Peninsula Valdes. 

 Surrounding the central core of mothers 

 are groups of adult males, scattered widely 

 about in the middle of the bay. They ap- 

 pear to be doing nothing except for engag- 

 ing in occasional bouts of furious breach- 

 ing — ^possible challenges to the group of 



males that has taken up a position closest 

 to the coast and with the greatest access to 

 the females. We do not yet know exactly 

 what is going on, but perhaps the males 

 nearest the shore help reduce the pressure 

 from other males on the mothers with 

 calves (thus increasing the chances that 

 calves will not be injured). 



There is no pair bonding, and on any 

 given day a male may mate with several 

 females. But since a female is slightly 

 larger than a male, she can easily avoid un- 

 wanted mating attempts. Whales mate 

 belly-to-belly, so one of the female's 

 strategies is to swim into shallow water 

 and scrape the male off on the bottom. 

 Once, when a male managed to squeeze 

 himself under a female in shaUow water, I 

 saw her flex her back dramatically so that 

 her head and tail Ufted out of the water into 

 the air, bringing many tons of weight bear- 

 ing down on top of him. He left. 



Another strategy: Instead of lying beUy 



up, the female puts her tail in the air, hold- 

 ing it there for minutes at a time. If the 

 male is to mate with her in this position, he 

 must put his tail into the air alongside hers. 

 But without his tail to act as a propeller, he 

 can't swim. He has to use his flippers to 

 drag his whole body, held in a vertical, 

 head-down position, around her as he tries 

 to achieve proper alignment with her. 

 Meanwhile, she simply revolves slowly 

 about her own long axis, keeping her ven- 

 tral slit just out of reach, and when she 

 needs to breathe, she slips off to one side 

 and grabs a few breaths. Whenever a per- 

 sistent male tries to get beneath her, she 

 roUs forward and raises her tail into the air 

 once again. 



A male's testes weigh 2,200 pounds, 

 making them the largest on earth (and par- 

 ticularly impressive when compared with 

 the 150-pound testes of the blue whale, the 

 largest animal in the world). Presumably 

 such large testicles have evolved because 



45 



