The development of the behavior and of the social interactions of a couple mother-calf of Tursiops truncatus (Cetacea, Odontoceta), belonging to a colony of 5 individuals housed in the Aquarius of Rimini, have been the object of a study carried out during the first year of life of the new borne (12 May 1995 - 12 May 1996). The method of sampling used has been "focal animal sampling" with 4 sessions at the day of video shot of 30 minutes for both the studied subjects. The sessions are carried out 2 times a week during the first 6 months of study and 1 time during the following 6 months. All through the 52 weeks of observation a total of 304 samples have been collected for both the items of the couple mother-calf, for the amount of 304h of observation.

Afterwards, the video data have been elaborated by means of The Observer 3.0 for Windows. The complexity of the nature and of the social relations of the analyzed subjects and the need to deepen the many aspects of the behavior of the couple mother-calf (evolution, allomaternal behavior, suckling, etc.), have made it necessary to adapt the reference ethogram to the characteristics of the computer program, in such a way as to optimize its use. Although our ethogram is divided in 5 behavioral classes, the configuration utilized with The Observer consists of a single behavioural class including a list of 84 behaviors; this is for the requirements of the study to have subsequent and not contemporaneous classes, so as not to alter the real duration of the individual behaviors. Moreover, the possibility of formulating only two modifiers (of which there are 71 divided in 7 classes) for behavior has reduced the amount of detectable information like, for example, in the case of the behaviors of contact between two individuals, for which the respective datum about the interested portions of the body has been partially lost. For each of the different examined aspects of our study it has reworked the standard configuration to obtain interfaces aimed at differentiated collection of data, afterwards the basic statistical analysis permitted by the software has been applied to these data, and the reports so obtained have been exported to other computer programs for a subsequent examination and statistical analysis (analysis of the variance, T-test, etc.).

In conclusion, the use The Observer 3.0 has provided an important contribution for the collection and for the analyze of data, even if many general problems connected with the behavioral complexity of the different species remain.