RESTING (LETHARGIC) BEHAVIORS OF CAPTIVE STUMPTAIL MACACA (MACACA-ARCTOIDES) CAUSED BY A SOLAR ECLIPSE

The influence of a total sun eclipse (Mexico, July 11, 1991) on the be havior of a captive troop of stumptail macaques (M. arctoides) was inv estigated. A heterosexual group of nine monkeys of different ages whic h live in outdoor captivity served as subjects. Their behavior was vid eorecorded continuously (13:00 to 14:05) on the day of the eclipse, an d it was compared with the behavioral reactions observed at nightfall and dawn (19:00 to 06:00 h, in Summer) in common days, so that the gro up served as its own control. During the peak of the solar eclipse, al l the animals (forming a single group) slowly ascended to the highest platform of the living area, which place was their habitual sleeping s ite in control days. Then, the macaques exhibited the reactions of see king shelter, flocking, decreased motor activity, and absolute silence . As sunlight began to increase, the general activity returned to norm ality. Behavioral reactions -some of them abnormal- to the phenomena a ccompanying the total solar eclipse were typically initiated by one ju venile female. Although the influence of the changes in other geophysi cal factors related to a total eclipse cannot be excluded, the authors assume that, considering the high degree of photoperiodic dependence in the rest circadian systems of non-human primates, the illumination changes were the main factor affecting the macaques behavioral reactio ns, producing a dormancy state which lasted only while adverse meteoro logical conditions associated with eclipse prevailed.