A Mantled Howler Monkey in Manuel Antonio National Park, Costa Rica. The largest of the 4 species of monkeys in Costa Rica, the "Howlers" are strictly vegetarians, spending all of their time in the forest canopy, usually up high. munching away on the lush vegetation.
They "mark" their territories with sound, by making a loud roaring noise, usually in the morning at daybreak, that can be heard for up to a mile. The howlers expend a great deal of energy when marking their territory (with sound). Thus, they only sound off when they feel it's necessary to protect their self-proclaimed territories which they do very aggressively. Note this one is holding on with his tail while he forages for food (leaves are his steady diet). September 23, 2007. Nikon D200 + Nikkor 70-200 f/2.8 VR at 190mm - 285mm in 35mm terms..