G. Lunavillegas et al., RESTING (LETHARGIC) BEHAVIORS OF CAPTIVE STUMPTAIL MACACA (MACACA-ARCTOIDES) CAUSED BY A SOLAR ECLIPSE, Salud mental, 17(3), 1994, pp. 49-52
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.