Effects of climate change on tree phenology and behaviour of red colobus monkeys (Procolobus rufomitratus) in Kibale National Park, Uganda
Abstract
Procolobus rufomitratus is a critically endangered species in Uganda with an only viable population in Kibale National Park. It is a folivore and one of the least studied in this habitat compared to its counterparts the frugivores and therefore knowledge about the species is crucial for conservation work especially in the context of a changing climate. This study explores how tree phenology, foraging, moving, resting and social behaviour of the species can be influenced by temperatures and rainfall and consequently how tree phenology (young leaf abundance) influence time budget of the red colobus. Regression analysis was used to examine how variations in rainfall and temperature influenced deviations in the peaks and troughs of phenology cycles. Regression analysis predicting young leaves availability from the abiotic parameters revealed a significant relationship for only two parameters, rainfall and minimum temperature. Increase in abundance of young leaves lengthened with the rainy season and reduced in the dry season. This increase in young leaves on trees suggests that rainfall and minimum temperature are very important in determining the leafing cycle. A similar analysis with maximum temperature did not suggest a significant association on young leaves.
In this study, the red colobus monkey spent greater time foraging (42.42%), resting (38.39%), moving (12.66%) and socializing (5.52%) respectively. Monthly variation in time spent foraging by the red colobus monkeys was significantly associated with variation in rainfall (p = 0.003, r2 = 0.1) and average maximum temperature (p = 0.016, r2 = 0.07). Time spent on social activities was significantly influenced by monthly minimum temperatures (p = 0.03, r2 = 0.05). Seasonally, the species depicted differences in seasons. The linear regression predicting time spent moving by monkeys found significant association during the rainy season (p = 0.02, r2 = 0.77), whereas no such association in the dry season. A Pairwise Mann–Whitney U test found significant association of minimum temperature on time spent by the monkeys foraging (p = 0.002) while maximum temperature and rainfall had no significant effects on the behaviour during the rainy season. Rainfall was significant in influencing time spent resting by monkeys in rainy season (p = 0.02, r2 = 0.73), whereas no such significant association was found with minimum and maximum temperature. This study gives a central indication of activity budget of red colobus monkeys in Kanyawara section of Kibale National Park.