FISHERY BULLETIN: VOL. 80, NO. 2 



All data were collected by experienced observ- 

 ers. Photographs taken in both 35 mm and 70 

 mm format documented most observations, and 

 were supplemented by written and occasionally 

 tape-recorded field notes. From the aircraft, ob- 

 servers estimated the critical dimensions of feed- 

 ing-associated structures with respect to refer- 

 ences such as the whale's body or flipper length. 

 From shipboard, more precise measurements 

 were obtained through reference to known 

 dimensions on the vessel, or to a 25 cm diameter 

 fiberboard disk which had been deployed in the 

 immediate vicinity of the whale. 



RESULTS 



Feeding behaviors were observed on more 

 than 150 occasions in the period April 1977 to 

 May 1980. Observations were made in the area of 

 West Quoddy Head, Mt. Desert Rock, Stellwagen 

 Bank, the waters east and southeast of Cape Cod, 

 and southeast of Block Island (Fig. 1). Feeding, 

 or apparent feeding, was reported for individ- 

 uals and for groups of up to 20 whales. 



Behaviors 



Circular Swimming/Thrashing 



On 2 December 1978, a single humpback 

 whale was observed and photographed swim- 

 ming in a broad (23 m) circle, roiling the surface 

 as it swam. Tail slashing (a rapid sideways 

 sweeping of the flukes) may have accompanied 

 this behavior. Dense flocks of birds were present 

 over the whale, and dolphins were present by the 

 head and body. The presence of both of these 

 feeding-associated elements, as well as the re- 

 semblance to observations by Ingebrigtsen 

 (1929), suggested that feeding was taking place. 



This initial observation was substantiated in 

 May 1980 when a number of shipboard observa- 

 tions confirmed the behavior as feeding asso- 

 ciated. An initial thrust of the flukes was fol- 

 lowed by the whale's swimming in a broad circle, 

 roiling the surface with flippers and flukes. This 

 was followed in many, but not all, cases by a feed- 

 ing rush through the circle. This behavior was 

 repeated many times by a single animal over a 

 period of several hours. 



The circular swimming/thrashing behavior, 

 observed on two occasions, each time involving a 

 single whale, is considered relatively uncom- 

 mon. 



FIGURE 1.— Study area where observations of feeding behav- 

 iors were made. Place names on chart are those referred to in 

 text. 



Lunge Feeding 



Lunge feeding is defined as an upward rush at 

 the water surface with the longitudinal axis of 

 the body intersecting the plane of the surface at 

 an angle of 30°-90°. As the whale breaks the 

 surface, the mouth is agape, and quite often a 

 greatly distended throat region is seen. Up to 

 one-third of the body length clears the surface 

 before the whale falls or settles back into the 

 water. Observations and photographs of prey at 

 the surface, in the mouths of the whales, and 

 picked up by closely associated birds leave no 

 doubt that this is a capture mode of feeding be- 

 havior. This common behavior has been recorded 

 in 21% of our feeding observations, from single 

 animals as well as from groups. When several 

 animals fed together, the lunges often were 

 simultaneous and in close proximity (3 m). In 

 several cases, two or more animals came in con- 

 tact, bumping each other as they lunged. Bouts of 

 lunge feeding may contain on the order of 20 

 lunges (3 animals in one case) in 25 min. 



The speed at which the lunge takes place is 

 highly variable. At times, the whale bursts 

 through the surface in a vigorous upward rush. 

 At other times, the rise to the surface and the 

 subsequent extension of the rostrum and dis- 



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