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Wild About Howler Monkeys

Friday, March 18, 2016

The first time Bill and I went to Costa Rica together, he was fixated on monkeys. He wanted to see a monkey. In his mind, that's when he'd truly be in the Neotropics. "I wanna see a monkey," he'd repeat, on the plane on the way down. It became sort of a mantra. I liked it because he says "monkey" in this weird, cute way. Mawnkey. It took awhile, but we finally did see monkeys, and it was awesome. I always enjoy seeing monkeys.

Howler monkeys are a special favorite of mine, because they transform the forest with their songs. I'm thrilled to pieces to be able to give you video I made of them singing as they go to bed. But that's dessert. First, a bit about howlers.

The species native to the dry forest in the north Pacific coastal zone of Costa Rica is the  mantled howler, named for the fringe of golden fur hanging off its flanks. There's also a black howler, and in the lowland tropical forest farther south is the beautiful red howler. I've seen all three species!  but not all in Costa Rica. This is a particularly beautiful mantled howler, likely a female. Look at the individual vertebrae in the prehensile tail; many New World monkeys have those, while Old World monkeys don't. If I had a tail I'd want a prehensile one. It would be very handy when you had toddlers.

One thing I absolutely adore about the dry tropical forest is that it's not very tall. So, as they make their way through the trees, you're much closer to these wonderful creatures than you are in humid lowland rainforest. The leaves in dry forest are much smaller and sparser, too, and the light's a lot better as a result. What you get from dry tropical forest is much better photos of monkeys than you can get at, say, Carara,  down near the Osa Peninsula, where the trees are wicked tall and the forest is dark. 

But mantled and black howlers present a real challenge to the photographer, because your camera will expose on their black hair, letting in more light to compensate for what it perceives as darkness, and the well-lit background is almost invariably "blown out" or overexposed as a result. My trick to keep that from happening is to expose and focus on a medium-toned branch or leaf right next to the animal, hold the shutter button halfway down, compose the shot and press it. That way I get a better-exposed shot.  This adorable girl came out OK, but the background is blown out.  I still love the shot, for her expressive face. What a cutie!

This one's somewhat better-exposed, but still a tough shot--a black monkey against a bright sky. The other thing that I noticed about this photo, as an illustrator, is the peculiar anatomy of the far hind leg. Weird, or what? If I drew it from this photo nobody would believe a monkey's leg could even do that. 
Mine sure couldn't! 
This is a very long-legged monkey--deceptively so. 
They kind of flow along the branches, very smoothly. She's just letting go of the trunk with that trailing foot, and the tail has a hold on a branch--it's her safety rope. Five points of contact ensure she won't fall. 

As monkeys go, howlers are phlegmatic and slow-moving. This is because they live on leaves, a relatively low-quality diet that takes awhile to digest. The caecum and colon are extra-long, and colonized by special cellulose-digesting bacteria. Howlers do a lot of lying around digesting, and they eat nearly constantly, as you would if all you had was SALAD. Whew. I don't know how they do it. I'd probably be more of a egg, lizard and bug-eating monkey. 

I had fun shooting this baby eating some kind of green fruit.

It amazes me how young they are when they're set free to just go brachiating along by themselves. 

She liked the little green fruits and could move freely in the small branches to nab them. 

It was a great privilege to stand beneath the trees where the troop was feeding, and be a part of their evening.

I got one shot that really captures the contemplative nature of the mantled howler, and it was nicely exposed, too. That's because I focused on the tree limb instead of the monkey. Please click on these to enlarge them. They really aren't as crappy as Blogger makes them look.

Male howlers use loud calls to advertise the presence and possibly the territory of a troop; to let other troops know a fruiting tree is occupied. They howl first thing in the morning (which can be 3:30 or 4 AM, ow!) and last thing at night. I will never, ever forget the first time I heard howlers. It was 1979, and I was trying to sleep in a crappy American hammock along the Rio Tapajos in Brazil's Amazon. We were deep in the forest. And at dusk came this sound like a storm in the treetops--haunting and powerful and actually scary. I had yet to see howlers, so my imagination ran wild. Never buy an American hammock. Brazilian ones are ever so much better.

Here's just a taste of the howler's song.  This male howler (ya think?) is making his way to a tree where he may spend the night with others of his troop. You don't often see them on the ground; they may feel safe around La Ensenada's camp; less likely to be attacked by a puma, jaguar or ocelot. 

You can get a feel for that deep voice. More on how it's produced and a real howler concert in the next post!


ROTF on that howler video. That monkey has swagger, in more ways than one! :D

Posted by Gail Spratley March 21, 2016 at 11:49 AM
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