NORMS and DOHL: BEHAVIOR OF THE HAWAIIAN SPINNER DOLPHIN 



ings provided a partial picture of the school and 

 individual movements. Our shipboard work with 

 dolphin schools was restricted almost wholly to 

 Kealakekua Bay through most of 1970. Only to- 

 ward the end of that year and during 1971 and to 

 a limited extent later, much sea time was spent in 

 other areas. Hence a large proportion of our sight- 

 ings do not bear on the question of dispersal dis- 

 tances or rates by individual dolphins. We 

 gathered no information on possible interisland 

 movements. 



By far the most useful scars and marks were 

 those of the dorsal fin. Twelve of our animals were 

 in this category (Figure 4). These animals could be 

 resighted from shipboard, and sometimes from 

 considerable distances. It is not surprising that 49, 

 (64%) of our 76 resightings were of these animals. 



Many marked animals had scars or pattern 

 peculiarities. Such marks could only be sighted on 

 dolphins at the bow of the observation vessel, or 

 from our MOC. The MOC was used sparingly be- 

 cause it was noisy and disturbed dolphin schools 

 and because it was safe only in calm seas. Thus, 

 information on repeated social associations within 



schools is limited to two sets of sightings and jour- 

 nal notes over 14 days, all within Kealakekua 

 Bay. In any school only a few individuals swam at 

 the bow of a vessel, while others stayed well clear, 

 thus reducing the chances of sighting many ani- 

 mals. Of 38 animals cataloged with body scars or 

 marks, there were 27 resightings. The final 

 marked animal recorded was an individual with a 

 vertical white stripe on its dorsal fin (Figure 4). 

 Our store of recognizable animals built up 

 slowly over the entire period of the study, thus 

 making interpretation of movements difficult; 

 nonetheless, some important ideas emerge: 1) 

 No resident school permanently and regularly 

 uses a given cove or local region of shoreline. In- 

 stead, each cove or resting spot may harbor a 

 given subgroup of dolphins for a matter of days or 

 weeks. 2) Schools are labile mixtures of groups 

 and subgroups. 3) Individual movements may 

 span the entire Kona coast, or even beyond (true 

 ranges of movement remain unknown). A few 

 "marked" individuals have been seen over rather 

 long periods, but other equally recognizable ani- 

 mals have been seen only briefly, or never again 



.911* 



'-S^-, 



FIGURE 4. — Spinner dolphin with vertical white stripe on both sides of its dorsal fin. We suspect that this animal had 

 shed a radio pack after the pin had migrated out of the fin. 



829 



