Function of loud calls in Howler monkeys

KITCHEN, D., DA CUNHA T.RG., HOLZMANN, I. & OLIVEIRA, D.

Howler Monkeys, Developements in Primatology: Progress and Prospects

Springer Press

Año: 2015; p. 369 - 399

Beyond the unique sound of howler monkey vocalizations, their vigorousloud calling displays are perplexing given the otherwise sedentary lifestyle of theseprimates. Here we provide potential explanations for this energetic investment byreviewing all available functional studies conducted to date. We highlight the variationamong and even within species when we explore whether male loud calls areused in group cohesion, predator avoidance, attraction of females, or competitionwith other males or other groups over resources. In the competition scenario, weexamine strategies of avoidance versus direct competition and whether contests arefocused on defense of space, food, mates, or infants. We suggest that much of thedebate surrounding the function of loud calls stems from methodological differencesamong researchers and from the varied levels of analyses used, although wealso demonstrate that studies of form and function can be intertwined. We emphasizethe need to examine different call types separately and discuss the role of howlingin intragroup male relationships. Finally, we address the understudied role offemale loud calling and the potential use of hybrid populations to examine theevolution of species-typical loud calls. We conclude with some practical hints fordesigning fi eld tests to uncover functional signifi cance.