Effect of solar eclipse on the behavior of a captive group of hamadryas baboons (Papio hamadryas)

To date there have been no systematic studies on the effects of a solar eclipse on the behavior of nonhuman primates. However, some descriptive studies have reported an increase in inactivity levels and congregation of individuals during a solar eclipse. The aim of the present work was to carry out a systematic study of the effect of a solar eclipse on the behavior of baboons at an individual, gender, and one-male unit (OMU) level. On 3 November 1994, Chile experienced a solar eclipse. A hamadryas baboon colony grouped in two OM Us at the Zoo of Santiago de Chile was observed 2 days before the solar eclipse (control situation), and during the eclipse for the same time period. Two observers simultaneously sampled the data. An all-occurrence sampling method was used to collect data on threats and attacks made by adult individuals. Simultaneously, instantaneous samplings of 1 min each were used to record behavioral states of the two mates and two females. In relation to the control situation, the effect of the solar eclipse on baboon behavior was a reduction in the rates of locomotion and threats, and an increase in the rates of inactivity and grooming, but not significantly so in all the focal individuals. Behavioral changes were more marked in males than in females, but did not differ between the two OMUs. Air temperature and humidity were similar in the two situations, and can therefore be discarded as causal effects on the behavioral changes of the baboons during the eclipse. (C) 2003 Wiley-Liss, Inc.