RESUMO

OBJECTIVES: We tested 4 main predictions, derived from life history theory and self-evident human diurnality, regarding maternal sleep behaviors in a non-industrialized population in which mother-nursling co-sleeping is universal and prolonged: (1) Night breastfeeding incurs a sleep cost to co-sleeping mothers; (2) Night breastfeeding increases with infant age, causing mothers to sleep less; (3) Sleep duration co-varies with darkness duration; (4) Access to electricity reduces sleep duration. DESIGN: Mothers self-recorded and reported nursing and sleep behaviors for a 48-hour period once per month (median = 5 months). SETTING: Rural Bolivian altiplano homesteads, primarily reliant on agropastoralism, scattered throughout the countryside surrounding a main town (altitude 3800 m; 17°14'S, 65°55'W; darkness duration 10-12 hours over the year). PARTICIPANTS: One hundred eighty-four co-sleeping mother-infant pairs (infant age 22-730 days). MEASUREMENTS: Breastfeeding frequency, and retiring and rising times for 885 48-hour observation periods. RESULTS: Maternal sleep duration covaried with darkness duration. Sleep duration was shorter in those with access to electricity (ie, living nearer to town) than those without access (more distant homesteads). Night breastfeeding rate was fairly steady until it began to decline after the first year postpartum. At a given infant age, higher night breastfeeding rates were associated with less maternal sleep. As their infants aged, mothers without electricity slept more, whereas mothers with access slept less. CONCLUSIONS: During the first year postpartum, more frequent night nursing shortens maternal sleep more than any other predictor variable. For older infants, the effect of night nursing diminishes, and even modest "modernization" (eg, access to electricity) is associated with shorter maternal sleep.

Assuntos

RESUMO

In this study, we examined the influence of demography and social context on mother-offspring conflict in wild black and gold howler monkeys (Alouatta caraya) inhabiting two nearby sites in northern Argentina, one comprising continuous forest and one fragmented forest. These sites differed in population density (3.25 vs. 1.04 individuals/ha), degree of home range overlap between neighboring groups (70 vs. 31%), and rate of intergroup encounters (2 vs. 0.02-1 encounters/day), though not in interbirth interval or rate of infant mortality. During a 27-month study (September 2008 through November 2010), we observed 37 mother-offspring dyads across the two sites. We found a very similar pattern of mother-offspring conflict in both populations; specifically, the sites did not differ in any of the variables used to characterize the mother-offspring relationship (the time spent in contact, the rate at which the mother makes and breaks contact, the rate at which the infant breaks contact, the rate of maternal rejection, and signs of infant distress) except one (the rate at which the infant makes contact). Although mother-offspring conflict is a dynamic process that varies over time, our results suggest that the different demographic and social contexts found at the two study sites did not have a marked effect on quantitative aspects of the mother-offspring relationship in these populations of black and gold howlers. Finally, this study suggests that the environmental variability (ecological, demographic, and social traits) leads to a set of strategies used both by infants and mothers with a main goal of conflict resolution, with mothers specifically aiming to cope with the tradeoff between current and future reproduction.

Assuntos

RESUMO

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.(AU)

Assuntos

RESUMO

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.

Assuntos

RESUMO

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.