Data from: Feeding strategies of brown howler monkeys in response to variations in food availability

Primates display varying degrees of behavioral flexibility that allow them
to adjust their diet to temporal changes in food availability. This trait
might be critical for the survival of folivorous-frugivorous species
inhabiting small forest fragments, where the availability of food
resources tends to be lower than in large fragments and continuous
forests. However, the scarcity of studies addressing this issue hampers
our understanding of the adaptive behaviors that favor the survival of
these primates in low-quality habitats. We conducted a 36-mo study testing
the hypothesis that brown howler monkeys (Alouatta guariba clamitans) are
able to adjust their diet in response to local and seasonal changes in
resource availability. We compared the diet of six free-ranging groups
inhabiting three small (<10 ha) and three large (>90 ha)
Atlantic forest fragments in southern Brazil and estimated the temporal
availability of their top food species (i.e., those species that together
contribute ≥80% of total feeding records). We found that brown howlers
exploited similarly rich diets in small (45, 54, and 57 plant species) and
large (48, 51, and 56 species) fragments. However, intermonth diet
similarity was higher for groups in small fragments, where howlers also
fed on plant items from nine alien species. Fruits and leaves were the
most consumed plant items in both small (42% and 49% of feeding records,
respectively) and large (51% and 41%, respectively) fragments. The
consumption of young leaves was higher in small than in large fragments,
whereas the consumption of other plant items did not show a pattern
related to fragment size. Regarding the contribution of growth forms as
food sources, only the exploitation of palms showed a pattern related to
fragment size. Palms contributed more to the diet of groups inhabiting
large fragments. The availability of seasonal food items–ripe fruits and
young leaves–influenced their consumption in both habitat types.
Therefore, brown howlers cope with local and seasonal fluctuations in food
availability by opportunistically exploiting resources. We believe that
this feeding flexibility is a key component of the phenotypic plasticity
that enables howlers to thrive in disturbed habitat patches, where periods
of scarcity of preferred foods shall be more common.