jorge ferrer and his coworker want to know how many of them are living in the los colorados nationalpark. they've been walking for three hours now. >> [whispering] look, another one! that's now three juveniles, three adults and one pregnant female let's see if there are any more surprises! >> what is it that he loves about monkeys? >> [whispering] maybe it's because they look like little people up there, that are asking themselves: "what are they doing down there? are they protecting us? or wanting to harm us?" look, they're watching us! >> the howler monkeys are just one of many species of ape living in the park which covers only 10 square kilometres. the cotton-top tamarin, for example, is found only in colombia and is a critically endangered species. the park is also home to several hundred species of birds. there even used to be jaguars in the region, but deforestation and farming have all taken their toll. the park is the last refuge for the animals, but it's too small. >> in the medium-term we're going to get problems with inbreeding and genetic exchange and it will be more dif