Activities displayed by animals are usually cyclic, and fluctuations in behavioural repertoires can be observed on a daily or seasonal timescale. The present study describes daily and seasonal variations in the aerial events – such as leaps, spins and slaps with body parts – by spinner dolphins in Baía dos Golfinhos, Fernando de Noronha Marine National Park, in Brazil. To measure aerial events by dolphins, we compiled and analysed data collected from January 2006 to December 2010. A total of 113,027 aerial events were recorded during 1431 days of land-based daytime observations. Our results show that the frequency of aerial events was positively correlated with the number of dolphins in the bay. The relative frequency of aerial events was higher in the rainy season, when compared with the dry season. Aerial activities also varied throughout the day, with dolphins being more active in the morning, specifically from 8:00 a.m. to 8:59 a.m., regardless of the season.

Very little information exists about the cetaceans of Aruba, Curaçao and Bonaire (ABC Islands), in the southern Caribbean. During the first dedicated cetacean surveys for the coastal waters of Aruba, photographic evidence for the occurrence of false killer whales (Pseudorca crassidens), Atlantic spotted dolphins (Stenella frontalis) and spinner dolphins (Stenella longirostris) was obtained. These represent the first confirmed records of P. crassidens and S. frontalis for the ABC Islands and of S. longirostris for Aruba.

The daily presence of spinner dolphins, Stenella longirostris, inside a small reef offshore the Red Sea coast of southern Egypt was monitored from January 2004 to January 2006. Observations indicated marked seasonal and daily variations in the use of the reef as a resting and socializing area by the dolphins, consistent during the two years of monitoring. Overall, the mean number of dolphins present in the reef at any day was 39.2 (SD = 39.34, range 0–210), with the lowest presence in February to April and the highest in June. Similar to other populations of this species in other oceans, dolphins entered the reef between daybreak and mid-morning, and started exiting during the afternoon hours. Although calves were seen in all seasons, a sharp peak was observed in June. Monitoring data provided indications relevant to governmental management efforts, which were implemented in 2004 to ensure that the dolphins could continue using the reef for their resting needs while a sustainable, respectful tourist activity is allowed in a designated zone of the reef adjacent to the dolphins' core habitat.

The aim of this work is to describe the repertoire of calls utilized by the spinner dolphins (Stenella longirostris) in the southern Atlantic Ocean. We measured four acoustic parameters of the fundamental frequency of each call: (i) duration; (ii) frequency amplitude; (iii) minimum frequency; and (iv) maximum frequency. We also classified calls by their shape contour by visual inspection of the spectrograms. The obtained values for call duration were 0.046 to 2.08 seconds (mean 0.433, standard deviation (SD) 0.433), amplitude of 0.13 to 2.01 kHz (mean of 0.36, SD 0.29), minimum frequency of 0.22 to 1.80 (mean 0.55, SD 0.29), maximum frequency of 0.46 to 7.50 (mean 1.00, SD 0.89). We classified 73 calls by spectral contour, identifying six basic types of discernible calls, showing heterogeneity among the call types, with C1, C2 and C3 calls presenting higher frequencies, 21, 30 and 23%, respectively. We found that the calls of S. longirostris in the Fernando de Noronha Archipelago are more diverse and complex than previously recognized for spinner dolphins and further studies worldwide can reinforce the broad use of this sound for the species repertoire.