Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Furthermore, D. guianense is considered a top food species in the diets of spider and howler monkeys (representing[80 % of their feeding time; González-Zamora et al. 2009; González-Di Pierro et al. 2011).
Category: