Influence of Arthropod and Fruit Abundance on the Dietary Composition of Highland Colombian Woolly Monkeys (Lagothrix lagotricha lugens)

Abstract

The woolly monkey’s (Lagothrix lagotricha) diet consists primarily of fruits, and for some populations fruit availability predicts its frequency in the diet. Woolly monkeys also eat new leaves, flowers, seeds and arthropods, but it is unclear whether arthropods are consumed in proportion to their environmental availability. We tested the hypothesis that arthropod consumption by woolly monkeys depends on availability. We studied a group of woolly monkeys for 10 months in 2013–2014, in Cueva de los Guácharos National Park, Colombia, in order to test the hypothesis that arthropod consumption by woolly monkeys depends on availability. We carried out surveys of plant phenology each month for 10 months to estimate fruit productivity, and every 2 months we also surveyed 3 canopy substrates (leaves, mosses and bromeliads) to quantify variation in arthropod biomass. During this time, we also quantified the diet of a woolly monkey group. The items most consumed were fruits (60%), followed by arthropods (24%), leaves (13%) and miscellaneous other items (3%). Arthropod biomass in the canopy did not vary considerably over the 10 months (0.014–0.037 g/g substrate) but was lower at the end of the second rainy season. A positive correlation was found between availability and entomophagy, but only when arthropods were relatively abundant. We did not find a relationship between arthropod and fruit feeding frequencies. Our results indicate that arthropods are prevalent in the diet of the woolly monkeys due to their abundance in Andean forest canopies.

Degree of Frugivory Predicts Rates of Food-Related Agonism and Intragroup Proximity in Wild Gray Woolly Monkeys (Lagothrix lagotricha cana)

“…In these species, switching to alternative food resources such as herbaceous vegetation or arthropods can mitigate feeding competition (e.g., Robbins 2008 ; Stevenson et al 1994 ). For example, common woolly monkeys excluded from fruiting trees may forage for arthropod prey, an alternative resource highly consumed in periods of high fruit availability (Fonseca et al 2019 ; Stevenson et al 1994 ). Therefore, the consumption of arthropods can buffer the negative effects of aggressive displacement from fruiting trees (Stevenson et al 1994 ; Stevenson and Castellanos 2000 ).…”

“…These studies should aim to identify and accurately measure fruit size and density within the canopies and the availability of alternative resources such as flowers and arthropod prey. They should also examine how the combined effect of the availability of these resources, especially fruit and arthropod prey, influence food intake (e.g., Fonseca et al 2019 ) and, consequently, the frequency of scramble and contest competition for food in light of socioecological models.…”

Dietary preferences and feeding strategies of Colombian highland woolly monkeys

“…In a previous study at Cueva de Los Guácharos we did not find a significant relationship between the arthropod biomass among tree species 16 , for that reason we randomly selected 20 trees inside the home range of the study group regardless of their species— Saurauia brachybotrys (Actinidiaceae), Tapirira guianensis subandina (Anacardiaceae), Hedyosmum cuatrecazanum (Chlorantaceae), Alchornea grandis (Euphorbiaceae), Incadendron esseri × 2 (Euphorbiaceae), Sapium cf . cuatrecasasii (Euphorbiaceae), Inga oerstediana (Fabaceae), Quercus humboldtii (Fagaceae), Juglans neotropica (Juglandaceae), Nectandra sp.…”

“…Woolly monkeys however are an important exception to ‘Kay’s Threshold’. They are one of the largest Neotropical monkeys, and invest a lot of time in foraging for insects, although fruits are the main component of their diet 16 , 17 . This behaviour suggests that arthropods may have an important nutritional value for this monkey species, as they do for other smaller primate species 5 , 18 – 20 .…”

“…Further, in lowland populations, woolly monkeys forage for arthropods in substrates such as leaves, dead branches and spider webs 23 , while Colombian highland woolly monkeys at Cueva de los Guácharos forage actively on epiphytic substrates (i.e. moss and bromeliads), that in Andean and sub-Andean forests, harbour a high number of arthropods and hold a constant resource through time 16 , 30 . This might explain why up to 39% of the diet of woolly monkeys from a highland population is made up of arthropods 17 .…”