Abstract The common bottlenose dolphin, Tursiops truncatus, is widely distributed. However, information about its ecology and behavior in Brazilian waters is scarce especially about the ‘offshore’ ecotype, an Evolutionarily Significant Unit in the Southwest Atlantic. We report for the first time the occurrence, behavior and habitat use of bottlenose dolphins Tursiops truncatus truncatus, in two Marine Protected Areas (MPA) in Cabo Frio coast, Brazil. There were fifteen sightings of different groups throughout the year. An overall of 429 individuals were photo-identified. 90.7% dolphins did not present a degree of residence, 1.4% dolphins were considered with high residency to the area, 5.8% medium and 2.1% low. Our habitat use map indicated dolphins were more common off ~10km from Cabo Frio municipality and between depths around 20-70m. Bottlenose dolphins on Cabo Frio coast were more frequently observed performing travelling, followed by foraging and socio-sexual behavior. Group sizes varied from three to 120 individuals. Larger groups were observed when travelling and foraging. Despite the existence of two local Marine Protected Areas, the fast human development in Cabo Frio may threaten this important area for bottlenose dolphins in terms of food resources and shelter from predators.

Bryde's whales, Balaenoptera edeni Anderson, 1879, were observed on 17 occasions (N = 21 surveys) in the coastal waters off Rio de Janeiro in southeastern Brazil during austral summer through autumn 2014. Five whales were individually identified using photo-identification techniques. The mean interval between resightings for all individuals was 12.8 days, with a minimum of one day and a maximum of 48 days. The comparison between the catalogs of Bryde's whales off Rio de Janeiro and the Cabo Frio region revealed matches for three individuals. The resightings show movements of up to 149.6 km along the coastal waters off the state of Rio de Janeiro. Most of the observations consisted of solitary individuals (82.3% of sightings). Feeding was the predominant behavior observed (47%), followed by milling (35.3%) and travelling (17.6%) in waters up to 48 m deep. Direct observations resulted in the addition of new prey, such as snubnose anchovy, Anchoviella brevirostris (Günther, 1868) and white snake mackerel, Thyrsitops lepidopoides (Cuvier, 1832), to the known diet of the Bryde's whale. A long time series of photo-identification efforts in the Rio de Janeiro, the Cabo Frio region and other areas can elucidate fundamental aspects of spatial and temporal site fidelity knowledge of Bryde's whales in southeastern Brazil.

Difficulties in quantifying behavioral events can cause loss of information about cetacean behavior, especially behaviors whose functions are still debated. The lack of knowledge is greater for South American species such as Sotalia guianensis (Van Benédén, 1864). Our objective was to contextualize the behavioral events inside behavioral states using a Permutational Multivariate Analysis of Variance (MANOVA). Three events occurred in the Feeding, Socio-Sexual and Travelling states (Porpoising, Side flop, Tail out dive), and five events occurred in the Feeding and Travelling states (Back flop, Horizontal jump, Lobtail, Spy-hop, Partial flop ahead). Three events (Belly exposure, Club, and Heading) occurred exclusively in the Socio-sexual state. Partial Back flop and Head flop occurred exclusively in the Feeding state. For the events that occurred in multiple states, we observed that some events occurred more frequently in one of the states (p < 0.001), such as Lobtail, Tail out dive horizontal Jump, Partial flop ahead and Side flop. Our multivariate analysis, which separated Socio-sexual behavior from Feeding and Travelling, showed that the abundance of behavioral events differs between states. This differentiation indicates that some events are associated with specific behavioral states. Almost 40% of the events observed were exclusively performed in one state, which indicates a high specialization for some events. Proper discrimination and contextualization of behavioral events may be efficient tools to better understand dolphin behaviors. Similar studies in other habitats and with other species, will help build a broader scenario to aid our understanding of the functions of dolphin behavioral events.

The coordinated feeding tactics used by delphinids are influenced by differences in the distribution of prey species, season, and opportunities for social learning. In the present study, we compared the coordinated feeding behavior of two populations of the Guiana dolphin, Sotalia guianensis, in southeastern Brazil, and how these feeding tactics vary seasonality and in the presence of calves. We observed eight types of coordinated feeding tactics, which differed in frequency and in the mean number of individuals engaged in them, and between both areas. Feeding tactics used to herd and capture prey were the most frequent and engaged a greater number of individuals, suggesting that these tactics are better for capturing fish that gather in larger schools. Furthermore, the seasons influenced the occurrence of different prey items, which in turn modified the feeding tactics of the dolphins. In the Ilha Grande Bay we observed that bouts lasted longer and larger groups engaged in the feeding tactics, which may be associated with the seasonal spawning of larger schooling fish such as Sardinella brasiliensis (Steindachner, 1879) (Teleostei: Clupeidae). However, in the Sepetiba Bay, we observed longer feeding bouts and a smaller number of individuals engaged in the feeding tactics during autumn-winter. This may be associated with the fact that the most abundant prey species, Micropogonias furnieri (Desmarest, 1823) (Teleostei: Sciaenidae), gathers in small schools. Calves were present in 95% of all coordinated feeding tactics that occurred in the Ilha Grande Bay and in approximately 61% of feeding tactics in the Sepetiba Bay, suggesting that these areas are important for social learning. This study provides more information about feeding tactics and improves knowledge of the coordinated behavior of Sotalia guianensis (Van Benéden, 1864).

Parental care is any form of parental behavior that increases offspring fitness. To the authors' knowledge, this study is the first to analyze the intensity of parental care in the Guiana dolphin, Sotalia guianensis (van Bénéden, 1864). The objectives of this study are as follows: 1) to quantify the degree of parental care in S. guianensis in Ilha Grande Bay, Rio de Janeiro; 2) to investigate the influence of behavioral state and group size on the degree of parental care; and 3) to evaluate the differences between the intensity of parental care provided to calves and juveniles. Our results indicate that the intensity of parental care is high in S. guianensis and that care is more intense in larger groups. It is possible that these differences serve to maximize hydrodynamic gains and to minimize risks. Our results suggest that parental care is more intense during travel. A possible reason for this greater intensity is that the feeding dynamics show a more random pattern than other behavioral states. Moreover, the results indicate that calves receive more intense care than juveniles. These results suggest that parent-offspring conflict is possible in the study population.

Differences in distribution, prey species, season and social learning opportunities influence the feeding tactics used by marine mammals. Here, we analyze the coordinated feeding behavior of the Guiana dolphin, Sotalia guianensis (Van Bénéden, 1864, Delphinidae) and its relation to seasonality and the presence of calves. In a total of 201 feeding bouts, we observed four types of coordinated feeding tactics, which differed in frequency and in mean number of engaged individuals. Tactics in which dolphins used their bodies to herd and capture prey were the most frequent, presenting a higher frequency and engaging a higher number of individuals, suggesting that these tactics are better for capturing fishes which form larger schools. Furthermore, the seasons influenced the feeding behavior used by dolphins. During spring-summer, a longer duration of bouts and a larger number of individuals engaged in the feeding tactics was observed, which may be related to the seasonal spawning of larger schooling fish, such as Sardinella brasiliensis (Steindachner, 1879). Calves were present in 95% of all coordinated feeding tactic occurrences. This study indicates a complete preference of dolphins for coordinating their actions to capture prey and for the first time reports the presence of calves in the coordinated tactics and jumps. This broadens the current knowledge of the Guiana dolphin feeding tactics.

Indivíduos da população dos golfinhos estuarinos, Sotalia guianensis (Van Bénéden, 1864), da Baía de Sepetiba (22º35'S, 44º03'W) Estado do Rio de Janeiro, sudeste do Brasil, foram catalogados pelo método de foto-identificação durante o período de fevereiro de 1994 a julho de 2006. Foram conduzidas 72 expedições de barco, resultando na identificação e catalogação de 217 botos. Destes 79 (36,4%) foram recapturados pelo menos uma vez durante o período de estudo; o intervalo médio entre as recapturas foi de 40,6 ± 31,1 meses. A presença de pares de mães-filhotes foi numerosa ao longo dos 12 anos de estudo e novos indivíduos foram constantemente identificados na área. Os resultados sugerem que parte desta população depende substancialmente do habitat fornecido pela Baía de Sepetiba, tanto para alimentação quanto para fins de reprodução, apesar de haver indivíduos que pouco se utilizam desta área.

Estuarine dolphins, Sotalia guianensis (Van Bénéden, 1864), were identified in Sepetiba Bay (22º35'S, 44º03'W), state of Rio de Janeiro, Brazil, between February 1994 and July 2006 using the photo-identification method. A total of 72 surveys resulted in the identification and cataloguing of 217 individual dolphins. Seventy-nine (36%) were resighted at least once during the study period. The average interval between resightings was 40,6 ± 31,1 months. Large numbers of mother-and-calf pairs were recorded during the 12 years and new individuals were frequently encountered in the photographic records. These results suggest that part of the dolphin population is more consistently found in Sepetiba Bay, probably for feeding and reproduction, while other individuals use the Bay only sporadically.

De julho de 2001 até junho de 2002, foram gravados um total de 2h55min de vocalizações do Golfinho-Tucuxi Sotalia fluviatilis da Baía de Sepetiba, Brasil (22º35'S-44º03'W). Um total de 3350 assobios foram analisados quantitativa e qualitativamente e foram divididos em 124 tipos, pelo aspecto visual nos sonogramas. Os seguintes parâmetros foram medidos: Freqüência Inicial, Freqüência Final, Freqüência Mínima, Freqüência Máxima, Duração, Número de Inflecções, Freqüência nos Pontos de Inflecção, Freqüência a 1/2, 1/4, e 3/4 da duração do assobio, Presença de Modulação da Freqüência e Harmônicos. O tipo de assobio Ascendente (N=2719) foi o mais comum, representando 82% do total. O comportamento dos golfinhos e a média do tamanho do grupo observado durante as gravações influenciaram os parâmetros de freqüência dos assobios quantitativa e qualitativamente. Os resultados demonstram grande diversidade dos assobios emitidos e indicam papel funcional destas vocalizações durante os comportamentos.

From July 2001 to June 2002, we recorded a total of 2h55min of Tucuxi Dolphin Sotalia fluviatilis vocalizations from Sepetiba Bay, Brazil (22º35'S-44º03'W). A total of 3350 whistles were analyzed quantitative and qualitatively and were divided into 124 types, by visual inspection of sonograms. The following parameters were measured: Initial Frequency, Final Frequency, Minimum Frequency, Maximum Frequency, Duration, Number of Inflections, Frequency at the Inflection Points, Frequency at 1/2, 1/4, and 3/4 of whistle duration, Presence of Frequency Modulation and Harmonics. Ascending type whistles (N=2719) were most common, representing 82% of the total. Dolphin behavior and average group size observed during recording influenced the whistle's quantitative and qualitative parameters. The results demonstrate the great diversity of whistles emitted and indicate a functional role of these vocalizations during the observed behaviors.