Circadian and Ultradian Periodicities of Grooming Behavior in Family Groups of Common Marmosets (Callithrix jacchus) in Captivity

Abstract

Three families' groups of common marmosets were observed to describe the characteristics of their grooming rhythmicity, as the duration of the episodes of self- and social grooming made and received by the animals, in captivity under natural environmental conditions. Data were collected by focal animal sampling, at 20 min hourly intervals during 16 non-consecutive days, from January to March in 1994 (sunrise: 05:24 h ± 2 min; sunset: 17:34 h ± 1 min). Time series were obtained for each individual and for each family through hourly duration of grooming. Family time serie was obtained through the mean of its individuals time series. Spectral analysis revealed statistically significant circadian rhythms for all families and individuals. Ultradian components were detected in 50% of the families and in 46.7% of the animals. Acrophases of self- and social grooming calculated by Single Cosinor took place between 9:21 h and 10:39 h, for the families. For individuals self- and social grooming made and received, acrophases occurred from 8:35 h to 12:43 h. The confidence limits of acrophases did not show differences between the families and the individuals within the families, irrespective of their sex, age and reproductive condition, suggesting that this behavior has a stronger temporal marking. Grooming has circadian and ultradian components of rhythmicity in captive families' groups of common marmosets, under natural environmental conditions. Since only some animals showed the ultradian component, it may be consequence of social or environmental masking, or yet phenotypic plasticity of temporal genotype. Further studies are needed to test these possibilities.