0.200. While it is unclear what percentage of affiliations were > and < 0.200, 

 Smolker et al. (1992) describe the 0-0.200 range as indicative of inconsistent 

 associations. Index levels of approximately 0.210-0.400 were found for female- 

 female affiliates in general. Values of approximately 0.510 were found for 

 high-level female-female affiliates ("cliques")- Index values for male affiliates 

 were spread between 0.210-1. Index values for males forming "male 

 alliances" were 0.800-1 (Connor et al. 1992). Male-female affiliations were 

 generally in the 0.210-0.400 range. Some high level associations have been 

 stable for at least 5 years. Differences were found in the association patterns of 

 males and females. Smolker et al. (1992) did not use sightings of single 

 dolphins (or feeding dolphins) in computing their index values. This will 

 tend to lower the index's denominator (see Methods) and so raise the values, 

 relative to other studies. 



A six year study in the San Diego, California area (Weller 1991, Defran 

 and Weller in press) lacked the frequent long-term high level associations 

 seen in Sarasota and Shark bays. A relatively small number of possible 

 pairwise combinations were not seen. For 160 dolphins, only 38% of possible 

 pairwise combinations fell between and 0.090. Thirty-three percent fell 

 between 0.100 and 0.190. Seventy-one percent of all possible pairwise 

 combinations were below the 0.190 index level. Mean index values for all 

 affiliations for individuals ranged from 0.135 to 0.299, with the majority of 

 mean index values from 0.177-0.239. Dolphins tended to associate with many 

 of the dolphins in the population; number of affiliates increased with 

 number of sightings (to 259 of 373 identified dolphins for one dolphin by the 

 end of the study). Some relatively high-level but short-term affiliations were 

 seen. Associations with index values of around 0.500 were estimated to have 

 durations of 1-48 months minimum for 20 of 40 reciprocal 1° affiliates. Low 

 resighting rates (66% of identified dolphins seen about once per year) 

 contribute to uncertainty about strength and duration of affiliations. 



In all of the above studies, many pair combinations have low, but non- 

 zero index values, indicating that for coastal populations of bottlenose 

 dolphins, most individuals have probably "met" each other. Unseen pair 

 combinations (those with index value = 0) may actually occur, but at 

 undetected levels. In Galveston, where the percent of unseen pairs was 

 relatively high, the number of possible pairs not seen dropped from about 

 72% in 1990 to about 63% in 1991. Mean index value for sighted pairs fell from 

 0.154 to 0.125 "probably from additional low-level associations being 

 discovered" (Brager et al. 1994). In all studies, the number of low-level 

 associations (those between 0-0.200) has been on the order of 70% of all 

 possible pairs (approximately 100% in the present study). 



28 



