HAIN KT AL.: FKKDINC BEHAVIOR OF HUMPBACK WHAI.K 



tance, although the data also suggest haddock, 

 mackerel, whitefish, and sand lance (Mitchell 

 1973; Sergeant 1975 6 ). The American sand lance 

 has been suggested as a prey species in the Cape 

 Cod area by Overholtz and Nicolas (1979). Our 

 direct evidence confirms their observations and 

 demonstrates the importance of this prey species 

 in these waters. The sand lance is similar in size, 

 summer habitat, and schooling behavior to the 

 more northern capelin, Mallotus villosus (Over- 

 holtz and Nicolas 1979), and therefore may oc- 

 cupy a similar role in the diet of humpbacks in 

 more temperate latitudes. Interestingly, Meyer 

 et al. (1979) reported a significant increase in the 

 relative abundance of sand lance since 1975 on 

 Stellwagen Bank, a trend which was typical of 

 the northwestern Atlantic from Cape Hatterasto 

 the Gulf of Maine. 



Indirect evidence suggests herring as a prey 

 species in the northern Gulf of Maine. Watkins 

 and Schevill (1979) also tentatively identified 

 herring, along with pollock, Pollachius virens, 

 from Cape Cod waters. These observations will 

 require confirmation as additional knowledge on 

 prey species in New England waters is gained. 



With regard to the capture mode of feeding be- 

 havior, our observations on lunge feeding closely 

 corroborate those of Watkins and Schevill (1979) 

 and Jurasz and Jurasz (1979). The observations 

 on underwater feeding by humpbacks were 

 almost always in association with bubble struc- 

 tures, although Watkins and Schevill (1979) 

 described several instances of underwater feed- 

 ing in the absence of such structures. 



"Apparent circling behavior" during feeding 

 was reported by Watkins and Schevill (1979). 

 Our description of what we term circular swim- 

 ming/thrashing behavior expands somewhat on 

 their observations. We speculate that the use of 

 anatomical structures and swimming motion in 

 the manner described bears some generic resem- 

 blance to the "flick feeding" reported from Alas- 

 kan waters by Jurasz and Jurasz (1979). This 

 would seem to be particularly true for the inside 

 loop behavior we have described. These behav- 

 iors may be placed together into a major subdivi- 

 sion of feeding behaviors, the various bubbling 

 behaviors being the other major subdivision. 



The effect of the whale's feeding behavior on 

 the prey species, and the advantage conferred to 



the whale, remains a subject for conjecture, since 

 few data are available. The bubbling behaviors 

 are perhaps the most intriguing. Based on ex- 

 periments with artificial bubble curtains, it is 

 known that under certain circumstances, cur- 

 tains of bubbles form an effective barrier to 

 schooling fish (Brett and Alderdice 1958; Smith 

 1961; Bates and VanDerwalker 1964). Whatever 

 the precise mechanism, it seems reasonable to 

 conclude that humpback whale bubble nets can, 

 and do, effectively corral schools of prey. 

 Whether bubble nets concentrate the prey 7 or 

 merely enclose and maintain naturally occurring 

 concentrations of prey (as hypothesized here) can 

 only be resolved by further study. 



The humpback appears well suited to these be- 

 haviors; Edel and Winn (1978) have described in 

 some detail the locomotion, maneuverability, 

 and flipper movement required to execute the 

 behaviors described here. It has been suggested 

 (Howell 1970; Brodie 1977) that flashes from the 

 long, white flippers are used to concentrate or 

 herd the prey. This may play a role in the circling 

 behavior, the bubble-netting, and perhaps other 

 types of feeding. In the case of bubble-netting, in 

 addition to their hydrodynamic function, the ver- 

 tical orientation of the two extended flippers 

 may act in unison with the bubble screen to help 

 form the "curtain" which herds and/or entraps 

 the prey. 



While bubbling behavior appears to be com- 

 monly associated with feeding (52% of our feed- 

 ing observations), some caution is in order. 

 Underwater bubbling, even in the presence of 

 feeding activity, may not always be directly re- 

 lated to feeding (see also Watkins and Schevill 

 1979). Underwater exhalations from humpbacks 

 in nonfeeding situations have also been observed. 

 On occasion, underwater exhalation by hump- 

 backs when approached by ships has been re- 

 corded. From field observations and study of 

 photographs, the possibility that some swim- 

 ming and bubbling behavior may be "play" be- 

 havior, particularly when displayed in the pres- 

 ence of closely associated dolphins, is recognized. 

 In the Pacific, Hubbs (1965) described under- 

 water exhalations with no clearly apparent func- 

 tion, and Forestell and Herman 8 described the 



6 Sergeant, D. E. 1975. An additional food supply for 

 humpback (Megaptera noraeangiiae) and minke whales (Ba- 

 laenoptera acutorostrata). Int. Counc. Explor. Sea, Mar. 

 Mamm. Comm., CM. 1975/No. 13:1-7. 



7 Earle, S. A. 1979. Quantitative sampling of krill (Eu- 

 phausia pacifica) related to feeding strategies of humpback 

 whales (Megaptera novaeangtiae) in Glacier Bay, Alaska. 

 Paper presented at The Third Biennial Conference of the Biol- 

 ogy of Marine Mammals, 7-11 Oct. 1979, Seattle, Wash. 



"Forestell, P. H., and L. M. Herman. 1979. Behavior of 



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