Diet and Feeding Ecology of Ateles chamek in a Bolivian Semihumid Forest: The Importance of Ficus as a Staple Food Resource

Abstract

We describe temporal patterns of food consumption by Peruvian spider monkeys (Ateles chamek) in a semihumid forest in lowland Bolivia. We assessed dietary composition in relation to temporal variation in abundance, duration, and synchrony of different food items in their home range. We collected data from September 2003 to September 2004, in the forestry concession La Chonta, Department of Santa Cruz. Throughout the period of detailed feeding data collection (February-September 2004), Ateles chamek used Ficus as a staple food resource. Figs constituted almost 50% of their diet in terms of total time spent feeding, and subjects consumed them to a great extent even during times of high overall food availability. This is contrary to the general expectation that for Neotropical frugivores, Ficus is a fallback food in times of fruit scarcity, rather than a staple food resource. Surprisingly, despite being considered ripe fruit specialists, Ateles chamek spent 18% of their feeding times eating unripe figs. Ateles chamek consumed unripe figs all through the year, including periods when ripe figs and other ripe fruit were abundant. We identify other important fallback foods for Ateles chamek in the forest, in particular the ripe fruit of Myrciaria sp.

Nutritional Ecology of Ateles chamek in lowland Bolivia: How Macronutrient Balancing Influences Food Choices

“…We consider this mean ratio to be their preferred region in nutritional space, as it appears to be defended by individuals in the face of large variation in diet composition Raubenheimer 1993, 1995). They reached this point in nutritional space either by consuming a small number of nutritionally balanced foods over the course of a day (here: foods that have a ratio of available protein:(TNC+lipids) similar to their For a description of how feeding behavior and diet composition in general was influenced by phenological changes, see Felton et al (2008).…”

“…Tall forest dominates the study area, with small sections of low vine forest, chaparral, and swamp (Felton et al 2008). There were 3 distinct phenological periods (seasons) during the study, including a period of high ripe fruit abundance (late wet season; February to mid-April) followed by a 10-wk period of fruit scarcity (early-mid dry season; mid-April to June) before ripe fruits became more abundant again (late dry-early wet season; July to September; Felton et al 2008).…”

“…We collected basal area information from all trees >10 cm diameter at breast height (DBH) within 71 0.1-ha plots distributed throughout the home range. A detailed description of the design and sampling of our phenology surveys appears in Felton et al (2008).…”

“…Further, protein intake did not vary across seasons despite dramatic fluctuations in food availability (Felton et al 2009b). Research on the spider monkeys in La Chonta further showed that although their diet contained as much fruit as other Ateles species, it differed in 2 respects (Felton et al 2008). First, figs (Ficus) were a staple food all through the year.…”

“…There are no similar reports of a comparable reliance on Ficus by this primate genus even though all spider monkeys eat figs (Di Fiore et al 2008). Second, the spider monkeys in La Chonta spent much time consuming unripe figs, even when ripe figs and other ripe fruits were abundant (Felton et al 2008). …”