Effects of Meteorological Factors on the Expression of Nesting Behaviour in the Sulawesi Babirusa (Babyrousa celebensis)

The impact of environmental stimuli on the expression of nesting behaviour of Sulawesi babirusa (Babyrousa celebensis) was explored over a period of 1339 days from 01 August 2006 until 31 March 2010 in a large animal enclosure on Bali, Indonesia. We found that nest building behaviour and the re-use of sleeping nests occurred more frequently in the dry season than the wet season and was clearly influenced by both a drop in the ambient temperature and an increase in wind speed. Additionally, net effective temperature (NET) computed from a combination of ambient temperature, relative humidity, and wind speed indicated a close relation to the nesting behaviour frequency; a decreasing trend of the expression rate of nesting behaviour with increasing NET in the early evening. Moreover, the trend of the expression rate by 12-hr NET fluctuation from 05:00 hr to 17:00 hr was also found out in all seasons. Meanwhile, 24-hr rainfall had a negative impact on the expression rate. These findings suggested that NET was a useful meteorological index to discuss the motivation to exhibit the nesting behaviour of babirusa, and also babirusa probably found thermal comfort in the sleeping nest.