Howler Sunset

In birds, the hyoid bone is a flexible Y-fork anchoring the tongue. In humans, it's a forgettable little scrap at the back of the tongue. In howler monkeys, it's really something else. 

 I had an excellent conversation with this male howler near the dining room at La Ensenada, an eco-dude ranch in Guanacaste, Costa Rica's cowboy country up north. We ooked and grunted and talked.  I don't know what I was saying, but it sure was a thrill to make contact with him. I started the conversation with an ook or two, imitating him, and he plopped down right there and had a good chat with me. Ook. Ook. Owwww. Owwwwwwwwwww ook ook ook. OOK!

As I wrote in the previous post, howlers use their voices to mark and hold territory--yelling takes a lot less energy than, say, chasing and fighting off other monkey troops. Which is good if you eat nothing but leaves and a little fruit. Pardon the blur. I got excited when he opened up that big ol' chamber at close range.

Male howlers are charged with the job of holding feeding territory for their troop; females busy themselves raising young. So males have some special equipment, other than the swag you can see. The hyoid bone is enlarged into a bony bulla, or sac, which makes a resonating chamber for his voice. It's as if he has a megaphone right in his throat. He's got one of the loudest voices in the animal kingdom. And as far as we know, this is the only mammal with a hyoid bulla made of bone, rather than esophageal tissue. Lots of monkeys and apes have large fleshy elastic laryngeal pouches (think gibbons and orangs) but only howlers have bony bullae.

1.These are the skulls of red howler monkeys (Alouatta seniculus). Female is on the left, and the male on the right.  

2. is the rear view of the skulls. A female howler has a nice bulla, too, but the male's is almost three times its size. So it's the males who can really roar.

Check out the incredibly deep and massive jaw bone on both sexes (3). That tells me I do not want to get bitten by a howler monkey. With masseter muscle inserts like that, they must have some tremendous crushing power! Let's face it. Nobody wants to get bitten by a monkey. So I try to be polite when talking with them, and not escalate things with empty rhetoric.

I've borrowed these photos from the University of Edinburgh Natural History Collections. You can read more at their page.  There's also a highly detailed discussion (condensed to a couple of sentences here) by Darren Naish at the excellent science blog, Tetrapod Zoology. 

I thank both sources for publishing such cool stuff online, where pikers like me can share it. They're welcome to my photos of the live creatures!

Are you going to grow up to have a bony bulla in your throat? What does that feel like, little monklet?

How is it to trip so lightly over a palm frond? To have a tail that reaches out like a fifth hand to grab whatever's nearest? To know you're not going to fall?

It feels good to be a howler, hanging with my troop in the dry forest, waiting for sunset. We're going to sleep down the slope tonight, where the bougainvilleas are blooming. I'll wrap my tail around a limb and drift off, blinking at the moon.

I was blessed--blessed!! to have a lovely group of travelers on Costa Rica 2016. And my dear friend Ann Hoffert came along which pretty much made my year. We had a lot of catching up to do, many stories to tell. I've known Ann for 13 years; she hand-crafted the Potholes and Prairie festival that Bill and I worked for 11 years. With Ann, we crafted uniquely North Dakotan experiences for festival goers like Pipits and Pie and the Prairie Ramble. Bill and I gave talks, played live music, and joyfully soaked up and shared the richness of the Potholes region, where all the ducks are born.

Ann and Ernie have watched our babies grow up. This is my favorite photo of her. Yep, that's Liam, when he was under 4' tall. Two platinum blondes in the June prairie sunshine.

It was a beautiful thing, an impossibly rich mix of social events, bird appreciation, prairie rambling,  sumptuous gardens, home-made food, and music. I hold those memories close in my heart.

After all that, to get to travel with Ann, and share some of the things I love about the Neotropics,  which is  yin to North Dakota's yang, was a great and precious gift. 

On this trip, Ann and I got to tell each other some of the untold stories of our abundant lives. Something best done as the full moon rises over the Golfo de Nicoya. Hard to believe it was already a month ago: I look and the moon is full again, Jupiter and his moons cuddling up next to her at sundown.

In this little clip, Ann and I stand beneath a tree where a howler troup is bivouacking for the night. You'll hear their song, that storm in the treetops. Come--stand there with us. Listen to them sing the moon up at La Ensenada.

Wild About Howler Monkeys

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!