Modeling the Ecological and Phenological Predictors of Fruit Consumption by Gibbons (Hylobates albibarbis)

Abstract

Understanding the ecological interactions between plant reproductive strategies and frugivore feeding behavior can offer insight into the maintenance of tropical forest biodiversity. We examined the role of plant ecological and phenological characteristics in influencing fruit consumption by the White-bearded gibbon (Hylobates albibarbis) in Gunung Palung National Park, Indonesian Borneo. Gibbons are widespread across Borneo, highly frugivorous and perform important seed dispersal services. We compare multiple models using information criteria to identify the ecological and phenological predictors that most strongly influence gibbon fruit use of 154 plant genera. The most important predictors of resource use were the overall abundance of a genus and the consistency of fruit availability. Plant genera can maintain constant fruit availability as a result of (1) individual stems fruiting often or (2) stems fruiting out of synchrony with each other (asynchrony). Our results demonstrate that gibbons prefer to feed on plant genera that provide consistent fruit availability due to fruiting asynchrony. Because gibbons feed more often on genera that fruit asynchronously, gibbons are more likely to disperse seeds of plant genera with this reproductive strategy. Research on other frugivorous species is needed to determine whether the results for gibbons are generalizable more broadly. Finally, these results suggest that asynchronously fruiting plant genera may be particularly important for habitat restoration in tropical forests designed for frugivore conservation.Abstract in Indonesian is available in the online version of this article.

Dietary diversity, feeding selectivity, and responses to fruit scarcity of two sympatric Bornean primates (Hylobates albibarbis and Presbytis rubicunda rubida)

“…For example, both studies ranked the liana Artabotrys as being the most highly selected genus for gibbons. Artabotrys exhibits low synchrony, so it is consistently available [41]. The high selectivity score for Artabotrys in both our study and previous studies indicates that gibbons are consuming this genus more than predicted based on availability, which is probably because it produces relatively high quality, sugar-rich fruits that are easy to process, as well as the fact that it is often available during periods of otherwise low food availability [41,68].…”

“…Artabotrys exhibits low synchrony, so it is consistently available [41]. The high selectivity score for Artabotrys in both our study and previous studies indicates that gibbons are consuming this genus more than predicted based on availability, which is probably because it produces relatively high quality, sugar-rich fruits that are easy to process, as well as the fact that it is often available during periods of otherwise low food availability [41,68]. Our selectivity results are also similar to those of gibbon hybrids ( Hylobates muelleri x albibarbis ) in the Barito Ulu research area, Central Kalimantan, Indonesia [69].…”

Prolific fruit output by the invasive tree Bellucia pentamera Naudin (Melastomataceae) is enhanced by selective logging disturbance

“…The ability to maintain a constant presence in the plant–seed disperser market may provide an attractive target for frugivores (Dillis et al . ), as it may ease their task of tracking fruiting schedules over space and time (Howe & Smallwood ). Furthermore, the fruit of B. pentamera is of relatively high quality ( i.e ., high sugar content and low in defensive compounds; Renner ), and production of new fruit appears to be relatively frequent.…”

“…Similar data had been collected for 200 native genera from the period of October 2007 through April 2013 by AJM (for justification of using genera instead of species, see [Marshall & Leighton , Dillis et al . ]). These existing data from native genera included only stems of sufficient diameter to produce fruit (Marshall & Leighton ).…”

“…We considered fruiting frequency as the most appropriate tool for comparison between B. pentamera and the native community, given the enormous amount of variation in fruit types ( e.g ., size, nutritional content, seeds per fruit), as well as evidence from this forest that fruiting frequency may be one of the best predictors of consumption by fruit dispersers (Dillis et al . ). We additionally determined frequencies with which B. pentamera trees had buds, flowers, and immature fruit, to address whether the frequency of ripe fruit was a result of frequent reproduction or an artifact of persistence across months.…”