Foraging strategies of black-fronted titi monkeys (Callicebus nigrifrons) in relation to food availability in a seasonal tropical forest

Abstract

Many primates have to cope with a temporal scarcity in food availability that shapes their foraging strategies. Here we investigated the changes in diet, activity, and ranging behavior of a group of black-fronted titi monkeys (Callicebus nigrifrons) according to the availability of the main high-nutritional-density item in their diet and the foraging strategy adopted when this food is scarce. We monitored one habituated group using instantaneous scan sampling over 1 year (533 h of observation, 61 days) in a seasonal tropical forest fragment (245 ha). We simultaneously collected data on food availability with fruit traps. The titi monkeys consumed fleshy fruits, the main high-nutritional-density item of their diet, in accordance with its availability, and the availability of this item modulated the ingestion of vegetative plant parts, a relatively low-nutritional-density food. During high fleshy fruit availability, the titi monkeys consumed more fleshy fruits, flowers, and invertebrates. They also traveled more, but concentrated their activity in a central area of their home range. Conversely, during fleshy fruit scarcity, they increased the breadth of their diet, switching to one richer in seeds and vegetative plant parts, and with greater plant diversity. At the same time, they reduced most energy-demanding activities, traveling less and over shorter distances, but using their home range more broadly. Corroborating the optimal foraging theory, titi monkeys altered foraging strategies according to temporal food fluctuations and responded to low fleshy fruit availability by changing their diet, activity, and ranging behavior. The adoption of a low-cost/low-yield strategy allowed us to classify them as energy minimizers.

Response of Bolivian gray titi monkeys (Plecturocebus donacophilus) to an anthropogenic noise gradient: behavioral and hormonal correlates

“…Consistent with a previous study (Dingess, 2013), the titis' home ranges at Yvaga Guazú overlap substantially and their size is among the smallest reported for the subfamily Callicebinae (Norconk, 2007;Bicca-Marques & Heymann, 2013;Huck, Di Fiore & Fernandez-Duque, 2020). Furthermore, the titis' travel speed (78-95 m/h) in the park was quite low compared with that (300-420 m/h) reported for the masked titi monkey, Callicebus nigrifrons, in a much larger patch of Atlantic forest (Nagy-Reis & Seitz, 2017). This is not surprising given the heavy deforestation around the park with little opportunity for family group dispersion.…”

Food availability, plant diversity, and vegetation structure drive behavioral and ecological variation in Endangered Coimbra‐Filho's titi monkeys

“…Moreover, to investigate the foraging strategies (predictions #1 and #2) of both Coimbra-Filho's titi monkey groups during periods of higher and lower food resources (density of fruiting trees and lianas), we compared the potential energy loss and gain between the two periods. Specifically, we used activities that have high energy demands (home range, dpl, HMR, and the number of revisits to the food resource in the small and large fragments: Krebs & Davies, 1993) as proxies for energetic expenditure, and then summed the time the monkeys spent exploiting fleshy fruits, seeds and flowers (Lambert, 2011) as a proxy for energetic gain (Heiduck, 2013;Nagy-Reis & Setz, 2017). We then tested if there were seasonal differences in activities with high energetic demand using Fisher's exact test with a Monte Carlo simulation (2000 replicates).…”

Sleeping above the enemy: Sleeping site choice by black‐fronted titi monkeys (Callicebus nigrifrons)

“…The mean temperature is around 21°C and annual precipitation about 1,400 mm (Cepagri UNICAMP, ; CIIAGRO, ). Detailed information about the study sites has been published elsewhere (Caselli, Mennill, Bicca‐Marques, & Setz, ; Gestich, Caselli, & Setz, ; Nagy‐Reis & Setz, ).…”