Dominance hierarchy and social grooming in female lion-tailed macaques (Macaca silenus) in the Western Ghats, India.

This article reports the structure of dominance and its relationship with social grooming in wild lion-tailed macaque females. The strength of dominance hierarchy was 0.79 on a scale of 0 to 1 indicating a moderate linearity in the ranking system. Dominance scores were converted into an ordinal as well as an interval scale. Grooming scores were also converted into interval scales using standard scores. Grooming received and grooming given correlated positively and negatively respectively with dominance ranks indicating that high ranking females received more and gave less grooming. Grooming was also positively related to encounter rates for dyads of females. More grooming among adjacent ranks, and grooming being more reciprocal, occurred only in the case of dominant females. The grooming patterns, therefore, appeared to be more of despotic than egalitarian nature. While ranking macaques into different Grades of social systems ranging from despotic to egalitarian, Thierry (2004) has placed lion-tailed macaques in Grade 3 corresponding to the 'relaxed' social system. Our results indicate that the grooming and dominance relationships in this species are more despotic, and hence, the Grade for this species requires to be shifted toward 2 or 1.

The primate frontal eye field and the generation of saccadic eye movements: comparison of lesion and acute inactivation/activation studies

The frontal eye field (FEF) of monkeys has been repeatedly implicated in the generation of saccadic eye movements by various experimental approaches. Electrical stimulation of most of the FEF produces saccadic eye movements, many cells have activities related to saccades, and it has anatomical connections with many other oculomotor ares. Surprisingly, complete lesions of the FEF have remarkably little effect on oculomotor behavior. Only when more cognitive aspects are tested is a deficit clearly detected. In contrast, acute inactivation of the FEF on monkeys with the GABA agonist muscimol produced much more severe oculomotor impairment. This difference is probably due to the acute nature of the muscimol effect, which does not allow time for reorganization of the control of eye movements before testing begins. In addition, acute activation of the FEF with the GABA antagonist bicuculline caused the monkey to make irrepressible saccades of the same dimensions as those electrically elicited at the site. These experiments further confirm the strong involvement of the FEF in the control of saccadic eye movements and fixation.

Conductas de reposo (letargo) de los macacos cola de muñón (Macaca arctoides) en cautiverio, causadas por un eclipse solar / Resting (lethargic) behaviors of captive stumptail macaca (Macaca arctoides) caused by a colar eclipse

Se estudió la influencia de un eclipse total del sol (México, 11 de julio de 1991) sobre el comportamiento de un grupo de macacos cola de muñón (M. arctoides) que viven en cautiverio exterior. Se empleó un grupo heterosexual de nueve monos de diferentes edades y cada sujeto sirvió como su propio control. Los animales fueron filmados durante aproximadamente una hora continua el día del eclipse (de 1300 a 1405 h), para comparar sus reacciones conductuales con aquellas observadas durante el anochecer y amanecer en días veraniegos ordinarios (de 19:00 h de un día a las 06:00 h del día siguiente). Durante la fase de totalidad del eclipse (13:20 h), los animales formaron un solo grupo y ascendieron lentamente a la plataforma superior dentro del área de vivienda. Este lugar fue el sitio principal para dormir durante los días de control. Mostraron conductas de búsqueda grupal de abrigo, disminuyó la actividad motora y guardaron absoluto silencio. Conforme finalizó el eclipse, la actividad general volvió a la normalidad. Las reacciones conductuales fueron iniciadas por una hembra juvenil, incluyendo una conducta atípica de exploración. Los resultados sugieren que el cambio en el nivel de iluminación fue el factor principal que afectó la conducta de los primates, lo que confirma la dependencia fotoperiódica de sus sistemas circadianos de reposo