Parental care behavior in the Guiana dolphin, Sotalia guianensis (Cetacea: Delphinidae), in Ilha Grande Bay, southeastern Brazil

Abstract

ABSTRACT. 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.KEY WORDS. Adult-offspring relationship; parent-offspring conflict.

Modelling habitat use by the Guiana dolphin, Sotalia guianensis, in south‐eastern Brazil: Effects of environmental and anthropogenic variables, and the adequacy of current management measures

“…In the present study, the core area predicted for the Guiana dolphin, between Pico and Cedro islands, is characterized by shallow waters (1.5–7 m deep) with high mean SSTs. These conditions are appropriate for parental care and the learning of coordinated feeding by the juveniles, given that most dolphin groups have a large proportion of calves and juveniles, and spend most of their time feeding in a coordinated manner (Tardin, Espécie, et al, ; Tardin, Especie, Nery, D'Azeredo, & Simão, ; Tardin, Galvão, et al, ). In fact, most of the prey in the study regions, such as the Brazilian sardine, king mackerel, Scomberomorus cavalla , whitemouth croaker, Micropogonias furnieri , smooth weakfish, Cynoscion leiarchus , and mullet (Begossi et al, ; FIPERJ, ), are also found in this area.…”

“…Non‐systematic routes were followed at a mean velocity of 10 km/h from the port at Tarituba (Figure ). When dolphins were sighted, the boat's speed was reduced to approximately 5 km/h and focal group follows (Mann, ) were conducted at a minimum distance of 50 m according to the protocol of previous studies (Espécie, Tardin, & Simão, ; Tardin, Espécie, Lodi, & Simão, ). Point locations of the dolphin groups were recorded using a GARMIN VISTA CX GPS device.…”

Coordinated feeding behavior of the Guiana dolphin, Sotalia guianensis (Cetacea: Delphinidae), in southeastern Brazil: a comparison between populations

“…At the Ilha Grande Bay, LODI (2003) observed 1,754 individuals in 54 groups; calves were present in 89% of the groups and juveniles in 87% (LODI 2003). In a recent study (TARDIN et al 2013a) observed that 94% of the groups have calves and/or juveniles. In the Sepetiba Bay, the population size is approximately 1,269 individuals (FLACH et al 2008), and calves are present in 80% of the groups.…”

20 years of research on the Guiana dolphin population of Sepetiba Bay, southeastern Brazil: What has changed?

“…To determine whether the occurrence of dolphin groups changed between the two time series, the G index to standardize the duration of the observation time accumulated during each time series (adapted from Tardin et al, 2013a) was used: where G i is the standardized proportion of the number of groups observed during sampling period i , N is the number of groups observed during sampling period i and n is the minutes of survey effort.…”

“…To determine whether the occurrence of dolphin groups changed between the two time series, the G index to standardize the duration of the observation time accumulated during each time series (adapted from Tardin et al, 2013a) was used:…”