Feeding ecology of groups of titi monkeys (Callicebus nigrifrons) in a semideciduous forest

Author(s)

João Victor de Amorim Verçosa

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2023-07-31

Examining board members

Eleonore Zulnara Freire Setz; Denise de Alemar Gaspar; Raul Costa Pereira

• Advisor: Eleonore Zulnara Freire Setz

Abstract

Food resources exhibit variations influenced by ecological patterns and processes across time and space, with availability associated with factors like seasonality. According to Optimal Foraging Theory (OFT), animals forage to maximize energy gain while minimizing foraging costs. The behavior, diet, and foraging strategies of monkeys are interconnected, leading us to investigate the feeding ecology of three neighboring groups (G1, G2, and G3) of a Latin American primate species, the titi monkeys (Callicebus nigrifrons), within the continuous semideciduous forest area of Serra do Japi (Jundiaí-SP). The study was conducted from April 2022 to March 2023, focusing on three important aspects for feeding ecology: activity patterns, diet composition, and the use of feeding patches. Titi monkeys dedicate most of their time to resting (37.4%), particularly during the rainy season. However, during the dry season, they allocate more time to feeding and moving. Despite the high cost of locomotion, titi monkeys adopt an energy maximization strategy by consuming high-quality food items, such as fleshy fruits. Fruits constitute the primary component of their diet, accounting for 58.6% of their food intake. The diet includes at least 80 species from 38 families, with Miconia cinnamomifolia (10.5%), Nectandra megapotamica (7.7%), Cryptocarya aschersoniana (5.8%), and Prunus myrtifolia (5.8%) being the main food items. The fruiting period of the first three species primarily occurs during the dry season, although the titis' diet differs between the dry and rainy periods due to the consumption of vegetative parts and flowers. We also found that they spend more time in feeding patches that are farther away and of higher quality (greater diameter, greater fruiting phenology, and larger fruit size). Therefore, the combination of activity patterns, diet, and patch use leads us to conclude that titi monkeys are energy maximizers. Even though resources are less available during the dry season, titis may invest more time in moving to obtain high-quality fruits in feeding patches that are also of high quality. Thus, they feed on fruits in similar proportions during the seasons and, during the rainy season, with higher resource availability, they can invest more time in resting. Additionally, we found differences in diet and behaviors among the groups, especially in relation to G1, which can be explained by the area they occupy, differences in resource availability, or inherent group characteristics. Therefore, our research shows the importance of integrating different aspects of a species' natural history, starting from the assumptions of OFT, to understand feeding ecology. Furthermore, we highlight the importance of studies conducted with multiple groups, considering the differences that may exist among them (AU)

• FAPESP's process: 21/11416-0 - Feeding Ecology of Black-fronted titi monkeys (Callicebus nigrifrons) groups in a Semidecidual Seasonal Forest (Jundiaí, SP, Brazil)
• Grantee: João Victor de Amorim Verçosa
• Support Opportunities: Scholarships in Brazil - Master