Howler monkeys are omnivorous and eat a range of different foods depending on their specific species and location. They primarily feed on leaves, fruit, nuts, flowers, eggs, insects, and small reptiles. In terms of leaves, they tend to focus on species that are rich in protein, such as Ficus, Cecropia, and Brosimum.
They also consume unripe fruits in abundance, as these tend to be high in nutrient content and easier to access. When it comes to nuts, they can feed on both wild and cultivated species, such as Brazil nuts.
Additionally, they feed on flowers when their dietary nutrient needs are not being met. Lastly, they can also eat insects, small reptiles, and occasionally birds and bird eggs.