durations in some individuals. If the longer durations are due to more 

 protracted times at the surface, then this could indicate that individuals differ 

 in their resting and /or feeding behavior. 



ASSOCIATIONS AMONG INDIVIDUALS 



While the association index values did not show many differences 

 between males and females, among freeze-branded dolphins; males with 

 many affiliates tended to have higher numbers of both male and female 

 affiliates and to spend less time with females than males with few freeze- 

 branded affiliates. At a low level, some females {e.g., FB515, FB521) associated 

 vdth many freeze-branded males, and some males {e.g., FB504, FB518, FB538) 

 associated with many freeze-branded females (Table 4, Fig. 10). 



Dolphins showed intriguing commonalities with their two highest level 

 associates. A dolphin and its V and 2° affiliates tended to be of similar age, 

 especially for males. Eleven of 14 T and 2° affiliates were of same sex pairs. 

 Some affiliations were greater than one and two SD above mean index 

 values. Several studies have considered affiliations > 1 SD above mean to be 

 "significant", using that level to establish sodobiologically important 

 groupings of individuals (Heimlich-Boran 1986, 1993, Wells et al. 1987, 

 Weller 1991). However, values < 0.2 are generally not considered biologically 

 significant {e.g., Weller 1991, Smolker et al. 1992). 



Brager et al. (1994) found mean index values of 0.125 among affiliatioris of 

 35 naturally marked dolphins in the Galveston Bay, Texas, area in 1991. 

 Approximately 63% of 595 possible pairwise combinations were not seen. 

 Approximately 70% of the sighted pairs had index values between 0.001 and 

 0.190, 23% between 0.200 and 0.390, and an additional 7% between 0.400 and 1 

 on the half-weight index. Some high level associations were apparently stable 

 over at least 19 months. 



Wells et al. (1987) and Wells (1991) report moderate index values 

 {e.g., 0.310, 0.560) among "female band" members, values in the 0.450-0.750 

 range for "strongly bonded" adult males, and values of 0.080-0.100 (0.150 

 considered high) for male-female affiliations in Sarasota Bay, Florida. The 

 majority of sighted pairwise combinations were between 0.010 and 0.200, and 

 the average number of affiliates was 60.5 (Wells et al. 1987). Some high-level 

 same-sex associations have been seen to be stable {i.e., high index values 

 remained high) at least 10 yr (Wells 1991). Variation was found in association 

 patterns with age/sexual-maturity for males and females. 



In Shark Bay, Western Australia, Smolker et al. (1992) report that 

 approximately 80% of p)ossible pairwise combinations were between and 



27 



