Fifteen years ago, as I was in the forest exploring Cerro Candelaria (now EcoMinga’s largest reserve at 2700 hectares) near Banos in Ecuador, I heard a familiar but always-impressive loud sound, like the roar of a lion on steroids. It was a Red Howler Monkey. This monkey is more common in the lowland Amazonian jungle where I used to live; that was the first time I’d heard them so high up in the mountains. (Note added Sept 7 2014: Their sound can carry several miles, or three to five kilometers!)
While the monkey’s demented howls were echoing across the distant canyon, a local campesino passed me on the path. I asked him about the source of the sound. He told me that he and the rest of the nearby village figured that the canyon was haunted by some kind of dangerous demoniacal creatures (“demonios” was the word he used). Some of the concerned villagers armed themselves and tried to find and kill whatever horrible thing was making this sound, but they were unable to find anything.
These people were colonists whose roots were in the high Sierra of Ecuador, where Howler Monkeys are completely unknown. No one in the village had any idea of what Howlers could do with their specially-modified vocal organs. A person hearing this sound for the first time would be forgiven for imagining the worst—in close quarters this is the most impressive sound in the jungle, and even when one knows the animal behind it, it takes a conscious effort to stay calm and not run for the hills. Listen for yourself, and remember that these recordings are at far lower volume than the actual sound!:
(These videos were not made in our forest– they are public YouTube videos made by other people that nicely capture the sound.)
We’ve seldom managed to get a look at these Howlers in the Candelaria Reserve, but one of our reserve caretakers, Luis Recalde, finally succeeded in photographing the “forest demon” a couple of months ago. The picture was taken in the rain and in poor light, but it is all we have of our “demons”.
Here is a better Wikipedia picture of the species:
Howlers are large monkeys, like the Woolly Monkeys of our previous primate post. Howlers and Woolly Monkeys are more closely related to each other than to our other local monkeys, and according to genetic evidence, they shared a common ancestor about 16 million years ago. Fragmentary fossils of primates similar to today’s howlers date to 12 million years ago. Our Red Howler Monkey is one of about ten species: seven or eight in the Amazon, one on the other side of the Andes in Pacific Ecuador, Colombia, and Panama, and two additional species farther north in Central America. Most of these species are very similar to each other except for color, and are allopatric (their ranges don’t overlap). The oldest evolutionary division within the group was caused by the rise of the northern Andes; this splitting between the howlers west and east of the Andes was recently dated to about 6.7 million years ago based on molecular clock evidence (Cortes-Ortiz et al 2003). To put that in perspective, this is about as long as humans have been separated from chimps! In contrast, the two Central American species of howlers have only been separated for three million years.
Howlers are virtually extinct in the mountains of east-central Ecuador where we work, but in other areas they have been able to survive in highly altered landscapes. This suggests that they were eliminated here by hunting, even though local people say they don’t taste very good. I have not heard howlers here in the last decade or so. But we think that since we have eliminated hunting in our reserves, the howlers should be able to return if there are enough survivors. Luis and other local people have seen several animals at once, so there is still a tiny population here, which may yet bounce back. If not, we may consider starting a re-introduction program. We’d love to hear the forest demons again!!
Cortes-Ortiz, L., Bermingham, E., Rico, C., Rodriguez-Luna, E., Sampaio, I., Ruiz-Garcia, M. (2003) Molecular systematics and biogeography of the Neotropical monkey genus Alouatta. Molecular Phylogenetics and Evolution 26: 64-81.